Trident

[Charley]

:idea: Anyone heard how fast these ultra light 900+ horsepower boats goes?

[WetWillie]

Run the numbers. Factor in the dual jet. Turbo motor, One of a kind, first of it type hull design. I would say 105 :jawdrop:

[Charley]

What...... you serious? 105? Well I saw 72mph on the website at 4500 RPMs with a redline of 6000rpms.... kind odd that after 3 years of waiting they wouldn't let her rip right outta the box but lets assume it can go 105.... isn't that what a the bigger wet layup deckboats are running with 900 hp?

[GrapeApe]

Isn't 105 Fast for a Deck Boat that Size... With a Jet??? If it turns out that it does over 100 MPH...
*** Grape Ape ***

[Charley]

Isn't 105 Fast for a Deck Boat that Size... With a Jet??? If it turns out that it does over 100 MPH...
*** Grape Ape ***
I would imagine Magic's deck and conquest's deck would both run 105 with 900 HP....

[XTRM22]

It's if-fey for 105, I think Doghouses MAgic cat ,open bow is running low 90's with 800 hp and a bravo. The Trident being a true deck boat, but lighter, but jet....dual jet and 900 hp. I'd say between 85-120 :rollside: (I want to be a politician when I grow up)
Chuck

[Havasu Hangin']

Jets still suck (no matter how great of a boat they are attached to)... :supp:

[Jrocket]

http://www.tridentgum.com/_images/gum_productshot.jpg

[WetWillie]

I say 90.. :eek:

[Phat Matt]

What...... you serious? 105? Well I saw 72mph on the website at 4500 RPMs with a redline of 6000rpms.... kind odd that after 3 years of waiting they wouldn't let her rip right outta the box but lets assume it can go 105.... isn't that what a the bigger wet layup deckboats are running with 900 hp?
If it can do 100 I don't think he would post that on the site for insurance reasons. I believe that the engines will be detuned a bit when you take delivery with an easy mod to let her rip.
I stood on one last weekend. They really do exist. :)

[Charley]

It's if-fey for 105, I think Doghouses MAgic cat ,open bow is running low 90's with 800 hp and a bravo. The Trident being a true deck boat, but lighter, but jet....dual jet and 900 hp. I'd say between 85-120 :rollside: (I want to be a politician when I grow up)
Chuck
nice sig senator foley :D

[Charley]

I'd also like to add that those who live in glass houses should not be hucking rocks :devil:

[Brian]

It's if-fey for 105, I think Doghouses MAgic cat ,open bow is running low 90's with 800 hp and a bravo. The Trident being a true deck boat, but lighter, but jet....dual jet and 900 hp. I'd say between 85-120 :rollside: (I want to be a politician when I grow up)
Chuck
Doghouse's Magic ain't running anything anymore... It swallowed an exhaust valve last trip out and made a big mess!
I'd curious to see how the Trident runs as well. Should be a real nice boat.
:cool:

[Havasu Hangin']

I'd also like to add that those who live in glass houses should not be hucking rocks :devil:
Who the hell uses the word "hucking" anymore? :confused:

[Froggystyle]

Thanks for the interest folks. Top speed? Who knows right now. There are some good guesses on here so far. We turned 72 with what on our dyno shows us at 615hp. Fact is, we used two "A" impellers that stopped even this big ass motor cold at 4300. We have neared completion of the "second generation" gearbox that will give us a mechanical advantage over the pump curve and allow us to dial the RPM's to more closely match our power output. That should be installed by the 15th of this month and ready for testing. Additionally, we have retained Jeff Bennett who is a bottom and hardware guru to help us optimize the performance left on the table with our combination. We are not quite done yet.
Also, as a note regarding performance, it is important to keep a lot of other factors than top speed in consideration. I was just perusing though one of the latest Powerboat mags and saw a lot of these big number deckboats with 15-18 second 0-60 times. Many with time to plane numbers in the 10+ range. You can get some big numbers with props, but often times it is at the expense of a useful performance envelope. Our 1.2 second or so time to plane speaks for itself along with a 0-60 time around 1/3rd of the quickest in the shootout, 1/4 of the fastest. With the new gears, it will only get quicker. With a 0-60 time of 18 seconds with two people in the boat, how useful do you think that boat will be with your family and friends on board?
Our boat is designed to haul a bunch of folks safely and comfortably at or around 70 mph. It will deliver at 70 mph with around 600 hp at the pumps. That there is overhead left in those numbers is clear. Apart from that, we will refrain from speculation as to top end numbers and focus on what we find to be the most important numbers. The ones that pertain to the ability to ski or wakeboard behind the boat with people in it, or for that matter come onto plane quickly and safely. I will not likely let a magazine test a boat with the performance improved for liability and insurance reasons. Our boat has a specific purpose and that is to be the party.
Hey Matt... why don't you let the folks know about picking it up in front with one arm? ;) The weight savings is real.
Weight has so much to do with performance. We know that now, and are committed to chasing that technology as far as reason and payoff permits.
All of that being said, hope to see some of you soon down here for a ride. I could use something like Kool-Aid for Trident. I am thinking about using beer as a substrate.

[Phat Matt]

Hey Matt... why don't you let the folks know about picking it up in front with one arm? ;) The weight savings is real.
Weight has so much to do with performance. We know that now, and are committed to chasing that technology as far as reason and payoff permits.
No doubt the boat is light and strong. The top half of a hull was resting on a stand and I could really lift the front of it up with one hand. If you had a person on each side you could lift the whole thing.
I think you should have Vodka instead of KoolAid. :D

[XTRM22]

Thanks for the interest folks. Top speed? Who knows right now. There are some good guesses on here so far. We turned 72 with what on our dyno shows us at 615hp. Fact is, we used two "A" impellers that stopped even this big ass motor cold at 4300. We have neared completion of the "second generation" gearbox that will give us a mechanical advantage over the pump curve and allow us to dial the RPM's to more closely match our power output. That should be installed by the 15th of this month and ready for testing. Additionally, we have retained Jeff Bennett who is a bottom and hardware guru to help us optimize the performance left on the table with our combination. We are not quite done yet.
Also, as a note regarding performance, it is important to keep a lot of other factors than top speed in consideration. I was just perusing though one of the latest Powerboat mags and saw a lot of these big number deckboats with 15-18 second 0-60 times. Many with time to plane numbers in the 10+ range. You can get some big numbers with props, but often times it is at the expense of a useful performance envelope. Our 1.2 second or so time to plane speaks for itself along with a 0-60 time around 1/3rd of the quickest in the shootout, 1/4 of the fastest. With the new gears, it will only get quicker. With a 0-60 time of 18 seconds with two people in the boat, how useful do you think that boat will be with your family and friends on board?
Our boat is designed to haul a bunch of folks safely and comfortably at or around 70 mph. It will deliver at 70 mph with around 600 hp at the pumps. That there is overhead left in those numbers is clear. Apart from that, we will refrain from speculation as to top end numbers and focus on what we find to be the most important numbers. The ones that pertain to the ability to ski or wakeboard behind the boat with people in it, or for that matter come onto plane quickly and safely. I will not likely let a magazine test a boat with the performance improved for liability and insurance reasons. Our boat has a specific purpose and that is to be the party.
Hey Matt... why don't you let the folks know about picking it up in front with one arm? ;) The weight savings is real.
Weight has so much to do with performance. We know that now, and are committed to chasing that technology as far as reason and payoff permits.
All of that being said, hope to see some of you soon down here for a ride. I could use something like Kool-Aid for Trident. I am thinking about using beer as a substrate.
Nice post Wes, the whole, people, skiing, and wakeboarding combination is a factor that alot of folks either forget or own 2 boats to accomplish. I really like the versitility aspect of what you're putting togather at Trident.
Chuck

[Froggystyle]

Nice post Wes, the whole, people, skiing, and wakeboarding combination is a factor that alot of folks either forget or own 2 boats to accomplish. I really like the versitility aspect of what you're putting togather at Trident.
Chuck
Thanks Chuck. You know the deal. That is why you have a nice high performance 22 footer.
Until I designed this boat, I felt strongly that the best overall combination of performance, utility and party could not be had in a 27+ foot package. The bigger boats gave up too much utility in search of a bigger upper end number, and they were too heavy to have any real lower end numbers with a single engine. Sure, stepping up to two engines is an easy way to gain performance at the 28' and up range... while doubling your gas, maintenance, motor, drive and headache cost, both initially and down the road. Fact is, I haven't ridden in any 28 foot boats that performed well with people in the boat, and I have ridden in numerous ones that you had to shift folks around in just to come up on plane. And people are concerned with top end??? Didn't make sense to me, but I don't think the same way most do.
I looked at MBrown2's very well set up wakeboard boat while on the river on Labor Day. Nice rig. Plus his DCB in the garage, which is obviously the ducks balls. Both are phenomenal boats, but Mike uses the wakeboat more because of increased utility. I wanted the utility and performance. But I am the idiot who drives a lowered hot rod diesel truck to work every day because my 'Vette and bike aren't quite utilitarian enough to justify bringing. What if I have to go pick something up? It certainly justified the greater expense when purchasing the truck... I am trying to fill the void between high performance and high utility.
And if you ask me how fast my truck is, my answer will be that I don't know. Not what it is for. Truth is, I know the theoretical top speed of my Corvette, but have never taken it that fast.
Drive-ability is my main concern, both with boats and cars. We built a ton of drive-ability into the Trident. I encourage anyone to come down and have a ride and see what they think for themselves.
Have a good evening... I am going home early.
Wes

[WILDERTHANU]

:idea:
WELL SON A BITCH (http://www.trident-metals.com/trident/tridentweb.nsf?open)

[mbrown2]

I wanted the utility and performance.
Thanks for the comments....BTW....Utility was not the first thing that came to mind while hanging out on the Revolution....It was the same feeling I would think you would get sitting in boat that was born out of the the marriage between a DCB and Schiada which were bred by very sea worth savvy boats of east coast construction......sick layup, nice graphix not over done, rigging well thought out, and motor that is normally only found in a Schiada...:)

[Boatlesss]

How efficent is a large hp engine coupled to a jet pump?
Each alone are not known to be efficent.

[Froggystyle]

How efficent is a large hp engine coupled to a jet pump?
Each alone are not known to be efficent.
You don't get any more "efficient" than an intercooled twin turbo-charged, sequential port, coil on cylinder fuel-injected powerplant. The means of making our power is the most efficient method around right now. While it is less efficient than a diesel or something, it is twice as efficient as a twin dominator 10-71 supercharged 540.
The dual jet drive is more efficient throughout it's entire range than an outdrive. Compared in similar 23 Deep V's, the dual drive has not only better acceleration and top end, but better gas mileage by quite a bit. Nothing quantified, but we will quantify it someday somehow and put a number to it. Tough to do, because our motor would not be a good match for a standard outdrive, and our hull alone is a huge advantage from an efficiency standpoint than a run of the mill deckboat.
I would speculate though that our twin turbo, dual jet drive powerplant is more fuel efficient in our boat than a 496HO/Bravo in anyone else's. With exponentially higher performance.

[Froggystyle]

Thanks for the comments....BTW....Utility was not the first thing that came to mind while hanging out on the Revolution....It was the same feeling I would think you would get sitting in boat that was born out of the the marriage between a DCB and Schiada which were bred by very sea worth savvy boats of east coast construction......sick layup, nice graphix not over done, rigging well thought out, and motor that is normally only found in a Schiada...:)
Thanks Mike. I am flattered by the comparison to two boats I respect highly and consider the top of the food chain in different genres. It would be accurate to say I was influenced heavily by both builders in a lot of respects while designing and building this boat.

[rivercrazy]

Here's a base line for comparison Wes.
My 4500 lb 25 deep V (24 degree) with a stock 496HO gets about 3.5 - 3.8 mpg at about 3500 rpm. And is cruising in the mid 45 mph range at that rpm. At 4K rpm its gps'ing 55mph. Minimum planing rpm is about 2200-2300. Top speed with 425 stock ponies is 72 on GPS (before I put mufflers on it about 69-70 with mufflers) relatively light load.
To me this is respectably efficient given the deep V nature of the hull, weight (my figure is probably a little low due to gas & stereo), length, and stock power plant.
Real curious what numbers your hull and setup will achieve after full dial in.

[Froggystyle]

Real curious what numbers your hull and setup will achieve after full dial in.
So am I, believe me. What was your 0-60 time, and could you pull a skier (not a wakeboarder) with four people in the boat?
Have you ever actually weighed the boat or is the 4500# figure from the manufacturer? Seems light given the plywood construction and full interior with stereo.
Thanks for the info. We will certainly be able to use it for relative comparison. It will be very tough to compare our boat to all of the other jet driven hydroplane deck boats on the market though... ;)

[rivercrazy]

Not sure of the 0-60 time but is respectable. I have pulled skiers with 5 people in the boat. Heavy weight single ski-skiers with competition skis take a little bit to pull up. But I have a ski wheel for that purpose.
Never have weighed the hull. The mfg states it weighs 4300 lbs. I think that is a little light given the gas tank holds 85 gallons and I have more than a couple hundred pounds of stereo in it. The bottom is balsa cored. The laminate is 100% vinyester. But has plywood floor that is glassed on both sides. Interior is a mix of stainless drop down bolsters and marine plywood interior (3/4 inch thick for the sub box). With gas I bet it pushes 5,000 lbs. But its a high freeboard, 24 degree deep V, full beamed boat. Could it be lighter with alternate construction methods - yup. But sometimes a bit of weight is an advantage when the water gets nasty.
Can't wait to hear what you final numbers are. Dual jet drives have to be more efficient than a single.

[andy01]

Here's a base line for comparison Wes.
Minimum planing rpm is about 2200-2300.
.
Very interesting. Two totally different boats, but my miinimum is like 2200 rpm. That is with the drives tucked and the tab all the way down and the boat is registering like 8 mph on the Garmin. It sounds crazy but when I pull the sticks back to the stops you can feel the boat drop in.
I also agree with a little heavier boat will help displace water on a rough day. If your boat wieghed 2,000 pounds it would get bounced all over the place. My boat is 4,200 with the outboards. No I didn't take it off the trailer and check it but that is what Spectre says. And I don't cut much water with it, my boat more a less floats over the waves and flys off the back of 5 footers. Where a heavier v would just cut through some of that water.
Andy

[riverroyal]

I would imagine Magic's deck and conquest's deck would both run 105 with 900 HP....
but mines 72mph with a stock 496HO,so with 900HP,100 plus is no problem

[Froggystyle]

but mines 72mph with a stock 496HO,so with 900HP,100 plus is no problem
What is the 0-60 time with a stock 496 or the time to plane? If you are running 72, I can't imagine the holeshot is setting the world on fire, but it is probably understandable considering the high top speed. How does it do with 8 people in it?
I have been in a 900+hp conquest that could barely get on plane with two people in it. I rode in a two speed Commander deck with a huge motor that also could not plane out in top gear. Both ran big numbers though... Rivercrazy talks about a "ski wheel" for pulling skiers with. My guess is, and I could be wrong, that in order to pull up skiers with folks in the boat, you need to give up some top end.
What top end do you think a 900hp Conquest would have that retained the ability to go 0-60 in under 10 seconds? Not 100mph, that I promise you.
And lastly, even though our motor will pull 900+hp, we are using 615. 72mph, 4300-4400 RPM's, with a phenomenal holeshot. Truth is, if we had let it rev on the dyno, we could have gotten 1100 or better out of it. More on a more "forgiving" dyno. We tuned it for 5800 RPM though, rev-limited it there and know that the jet will never let it turn higher. Physics and all...
Time will tell what the motor will do at full RPM, but when we finish testing different compinations, we will let everyone know for sure.

[Dave C]

thats not bad.... much better than a regular ol single jet. Can't wait to see some more.
I suspect that some of the lighter cats can match or beat this..... but then again those guys are cheaters so they don't count........ ;)
we are using 615. 72mph, 4300-4400 RPM's, with a phenomenal holeshot. .
although you may have something there ... if you can even get close to the performance of the outdrive with a jet we would not have to worry about broken outdrives anymore...... the good ole days when we could run big power and not worry about breaking jetdrives.
I can't tell you how many times I have said... "I would build a bigger motor for my boat if I wasn't worried about breaking my drive" :yuk: :yuk:

[Froggystyle]

thats not bad.... much better than a regular ol single jet. Can't wait to see some more.
I suspect that some of the lighter cats can match or beat this..... but then again those guys are cheaters so they don't count........ ;)
although you may have something there ... if you can even get close to the performance of the outdrive with a jet we would not have to worry about broken outdrives anymore...... the good ole days when we could run big power and not worry about breaking jetdrives.
I can't tell you how many times I have said... "I would build a bigger motor for my boat if I wasn't worried about breaking my drive" :yuk: :yuk:
I liked the idea so much I built a whole boat around it. Plus, the maneuverability is through the roof, and you have the added safety factor of the jet drives with a party on board.

[Dave C]

the drunks are worse than the kids around those sharp thingeys.....
you have the added safety factor of the jet drives with a party on board.

[Froggystyle]

the drunks are worse than the kids around those sharp thingeys.....
Well, I didn't mean a Chuck E Cheese party on board... ;)
Let's just say I designed a lot of the surfaces on the boat to be safer to fall off of and on than a lot of boats.

[weekendwarrior]

Thanks for the info. We will certainly be able to use it for relative comparison. It will be very tough to compare our boat to all of the other jet driven hydroplane deck boats on the market though... ;)[/QUOTE]
Wow, thats a jet hydro? How does that work? I remember Jack Davidson never got that to work. It didn't look like yours though. Yours looks like a tunnel.

[Havasu Hangin']

For comparison...Jimmy's 28' Conquest had a Merc 575SCi and ran 90+ MPH no problem. Pulling a fat ass on a single competition ski? No problem.
The dual jet drive is more efficient throughout it's entire range than an outdrive.
:jawdrop:

[andy01]

For comparison...Jimmy's 28' Conquest had a Merc 575SCi and ran 90+ MPH no problem. Pulling a fat ass on a single competition ski? No problem.
:jawdrop:
How was it skiing behind Jimmys boat? :lightsabe
Andy

[Dave C]

beautiful... :rollside: :rollside: :devil:

[Froggystyle]

For comparison...Jimmy's 28' Conquest had a Merc 575SCi and ran 90+ MPH no problem. Pulling a fat ass on a single competition ski? No problem.
:jawdrop:
With six folks in the boat?

[andy01]

Better yet I would like to see a Conquest and a Trident run across Havasu on a wind blown afternoon. It would be interesting to see how that Trident does with the big water and how much trouble the drive has keeping the pump loaded sence it would be out of the water most of the time.
Andy

[Boatlesss]

The dual jet drive is more efficient throughout it's entire range than an outdrive.
I would speculate though that our twin turbo, dual jet drive powerplant is more fuel efficient in our boat than a 496HO/Bravo in anyone else's. With exponentially higher performance.
While your engine might be as efficient as you state, the dynamics of a jet pump argue differently.
A jet pump, one two or there or more, are efficient in a only specific narrow range of performance. Your boat being as fast as it is does not lend itself to the efficiency of a jet pump.
Rather a propeller is found to be more efficient over a varied range of speeds.
For a jet to be efficient, one as to stay within the window of efficiency. To slow and the efficiency does not exist, to fast and the efficiency does not exist. It is a very narrow window. KaMeWa, Hamilton, Dome, and even Berkeley confirm this in their testing.
Do you have a fuel flow meter tied to a GPS to check the efficiency at varying speeds?
Now you do reap the benefits of a jet pump for your application of a wake board boat as the jet is very efficient at planning and out of the hole acceleration.

[Froggystyle]

While your engine might be as efficient as you state, the dynamics of a jet pump argue differently.
A jet pump, one two or there or more, are efficient in a only specific narrow range of performance. Your boat being as fast as it is does not lend itself to the efficiency of a jet pump.
Rather a propeller is found to be more efficient over a varied range of speeds.
For a jet to be efficient, one as to stay within the window of efficiency. To slow and the efficiency does not exist, to fast and the efficiency does not exist. It is a very narrow window. KaMeWa, Hamilton, Dome, and even Berkeley confirm this in their testing.
Do you have a fuel flow meter tied to a GPS to check the efficiency at varying speeds?
Now you do reap the benefits of a jet pump for your application of a wake board boat as the jet is very efficient at planning and out of the hole acceleration.
In a clinical situation, this might be actually true. Kamewa, Hamilton and Berkeley do show that at cruise, in the case of a yacht, ferry or otherwise a jet drive does lose efficiency to a properly set up prop for that cruise speed. You gain quite a bit of performance over a broader range with them though, in addition to the greater maneuverability, less maintenance, quieter, less vibration and stronger acceleration offered by the jet drives.
We don't "cruise" though, and I didn't build the boat to maximize fuel efficiency. It is a welcome by-product of the drive however. With a broader range of significantly better performance, the jet drive is handily the best application for the deckboat. I did give up some top end for sure, but I gained exponentially more driveability.
I consider 70mph to be a high speed cruise for a deckboat. It will reliably run that all day. With 125 gallons of fuel, it actually will run that all weekend with most people's standard usage.
Will it fit every need? No, and we are not trying to. The person we are trying to build a boat for has probably had two or three very expensive boats. They probably will spend a lot of time in the boat, not just around it and they are ready for something that is built better and with more consideration than their last boat. This comes down to ease of use, reliability, performance, image, driveability, safety, durability and value. People who drive the best do so for a reason. It is no secret that a $7000 imported production motorcycle handily outperforms nearly every single $100,000 custom chopper on the planet. That fact means little to the person who is buying the Hot Match for a completely different reason.
I have no doubt many who buy the Revolution will be buying a slower boat than they currently own. It will be far more usefull though, and provide significantly more good times on the water than whatever ride it is that stays in the garage that weekend.
Nobody I know who is looking at the boat is particularly concerned with the MPG. All have been absolutely blown away at the fit and finish, attention to detail, accelleration and committment by the company to build the very best, not just the very best in the industry.
As I keep saying, come on down... When the boat is finally complete, I will take the Pepsi challenge with any deckboat on the market, and I will do it with my stock boat.

[rivercrazy]

For the days were out skiing, we don't worry about top speed. Fortunately changing a prop only takes a few minutes.
My priorities don't include all out top speed. I prefer versitility (interior configuration, great handling, ability to run rough water comfortably, ability to run in the salt and big lakes, room for a decent stereo, ease trailering, etc)
Most go fast boats I see are single purpose. Get from point to point in no time flat - then park it for the day. And the maintenance requirements on those high performance boats end up eating into your on water time.

[Froggystyle]

My priorities don't include all out top speed. I prefer versitility (interior configuration, great handling, ability to run rough water comfortably, ability to run in the salt and big lakes, room for a decent stereo, ease trailering, etc)
Those are very similar to my priorities. I think (hope) they are similar to a lot of people's priorities.

[rivercrazy]

Those are very similar to my priorities. I think (hope) they are similar to a lot of people's priorities.
I also believe the majority of folk are looking for this as well.

[Froggystyle]

I also believe the majority of folk are looking for this as well.
One can only hope.

[Froggystyle]

Just thought I would throw this in here....
Here is the dyno chart. The straight line is the hp. Nearly linear. It is certainly in no danger of rolling over anytime soon. What you see is 918 @ 5800 RPM. You can see why this thing is easily considered over 1000hp on pump gas.
730 ft/lbs of torque at 3600 RPM's too. I don't know of a lot of drives other than the jet that will hold on to that...
http://www.tridentboats.com/news/22/twins/graph.jpg

[dicudmore]

Just thought I would throw this in here....
Here is the dyno chart. The straight line is the hp. Nearly linear. It is certainly in no danger of rolling over anytime soon. What you see is 918 @ 5800 RPM. You can see why this thing is easily considered over 1000hp on pump gas.
730 ft/lbs of torque at 3600 RPM's too. I don't know of a lot of drives other than the jet that will hold on to that...
http://www.tridentboats.com/news/22/twins/graph.jpg
I concur...that would scatter most drives :D

[Charley]

jets suck :(

[Phat Matt]

jets suck :(
I hear they spit too. :(

[Havasu Hangin']

With six folks in the boat?
Yeah, but we cheated...but they were all rowing. :notam:
Doesn't a jet intake need to be planted in the water? :confused:

[Froggystyle]

Yeah, but we cheated...but they were all rowing. :notam:
Doesn't a jet intake need to be planted in the water? :confused:
Yep... Hence the hydro. The primary running surface and weight supporter on the boat is the rear of the center sponson. The side sponsons stabilize the boat, provide floatation and displacement at rest and the inside edge provides a turning surface for the jet to work with. Additionally, the outside sponson (relative to turn) has a pronounced lifting strake to assist in the inside roll during maneuvers.
Once we had a couple of initial setup issues taken care of after the first voyage, we haven't burped the jet since. Plus, the hull made a big day on Parker seem like a small day at San V.

[Froggystyle]

jets suck :(
Let me promise you this Charley, the last thing any boat manufacturer should wish to have happen would be for me to put a prop in our boat. With a several thousand pound weight advantage and significantly better performance characteristics, it would be like a Quizno's commercial against anyone in the market currently. Right now at least they can blame the performance bias on the huge power and jet drive propulsion.
Thing is, everyone who has ridden in our boat can't imagine putting an outdrive in it. It is available, and if someone spec's it, I am very interested in the result. It is not the best drive for the genre though, and when I want to really haul ass, I will buy an F-29. Or an MTI for real big numbers. That is what I will push limits in.
Anyone who wants a very, very powerful and safe deckboat that is truly the top of the game in all aspects need look no farther.

[phebus]

when I want to really haul ass, I will buy an F-29. Or an MTI for real big numbers. That is what I will push limits in.
Very nice throwing that DCB praise in there for Charley. LMAO :) :D

[Havasu Hangin']

Yep... Hence the hydro. The primary running surface and weight supporter on the boat is the rear of the center sponson.
So you're saying that you have more hull in the water than a "non-jet" tunnel?

[Charley]

I changed my mind... Jets Blow! :rollside:

[Infomaniac]

So you're saying that you have more hull in the water than a "non-jet" tunnel?
Read very slowly.......
I T S N O T A T U N N E L :D :D

[Havasu Hangin']

Read very slowly.......
I T S N O T A T U N N E L :D :D
Here...read this slowly...
I N E V E R S A I D I T W A S
I'm just camparing to the other boats he is comparing it to (tunnels).

[Froggystyle]

So you're saying that you have more hull in the water than a "non-jet" tunnel?
Like Ron said, it isn't a tunnel. And "more hull" is relative. More running length? Yes. More depth? No. With our wider, flatter and longer running surface, combined with the several thousand pound weight loss due to construction methods we not only draft less water at rest, but far less at cruise. Our wetted surface is right around 2" at 20mph or so and 10" at rest.
Shorter, deeper running lengths are terrible for efficiency. The longer and flatter you can use the water going under your boat the better. Problem is, most designs that do this are long v-bottoms. They are efficient, but lack stability and can chine walk easily without tabs.
As a hydro we are off to the side somewhere. But one promise, your basic "tunnel hull" boats don't work the way that you think they do. They definitely don't work the way the guy who designed them thinks they do. They work, but the west coast guys don't understand why.
Some east coast guys do though. That is why people who have imitated Peter Hledin's bottoms and tops are becoming successful out here these days.
If you are curious as to whether or not your boat is generating ANY aerodynamic lift, you can do a quick test to find out for yourself.
1) Do you have an open cockpit?
2) Do you have a bow rider?
If the answer is yes to either of these two... you are not using air for lift. And anyone who knows anything about basic aerodynamics is scratching their heads right now and realizing why.

[Dave C]

I always thought they did but now that you put it that way I guess they don't.....
If the answer is yes to either of these two... you are not using air for lift. And anyone who knows anything about basic aerodynamics is scratching their heads right now and realizing why.

[gmocnik]

silly rabbitt, wings (and aerodynamic lift) are for planes...
well i think the principal also works for many other applications...does a formula 1 car or and indy car have an enclosed capsule or is it essentially "open"??
so many theories, so few facts......
http://www.allstar.fiu.edu/aerojava/airflylvl3.htm
A Physical Description of Lift
Level 3
Almost everyone today has flown in an airplane. Many ask the simple question "what makes an airplane fly"? The answer one frequently gets is misleading and often just plain wrong. We hope that the answers provided here will clarify many misconceptions about lift and that you will adopt our explanation when explaining lift to others. We are going to show you that lift is easier to understand if one starts with Newton rather than Bernoulli. We will also show you that the popular explanation that most of us were taught is misleading at best and that lift is due to the wing diverting air down.
Let us start by defining three descriptions of lift commonly used in textbooks and training manuals. The first we will call the Mathematical Aerodynamics Description which is used by aeronautical engineers. This description uses complex mathematics and/or computer simulations to calculate the lift of a wing. These are design tools which are powerful for computing lift but do not lend themselves to an intuitive understanding of flight.
The second description we will call the Popular Explanation which is based on the Bernoulli principle. The primary advantage of this description is that it is easy to understand and has been taught for many years. Because of it’s simplicity, it is used to describe lift in most flight training manuals. The major disadvantage is that it relies on the "principle of equal transit times" which is wrong. This description focuses on the shape of the wing and prevents one from understanding such important phenomena as inverted flight, power, ground effect, and the dependence of lift on the angle of attack of the wing.
The third description, which we are advocating here, we will call the Physical Description of lift. This description is based primarily on Newton’s laws. The physical description is useful for understanding flight, and is accessible to all that are curious. Little math is needed to yield an estimate of many phenomena associated with flight. This description gives a clear, intuitive understanding of such phenomena as the power curve, ground effect, and high-speed stalls. However, unlike the mathematical aerodynamics description, the physical description has no design or simulation capabilities.
The popular explanation of lift
Students of physics and aerodynamics are taught that airplanes fly as a result of Bernoulli’s principle, which says that if air speeds up the pressure is lowered. Thus a wing generates lift because the air goes faster over the top creating a region of low pressure, and thus lift. This explanation usually satisfies the curious and few challenge the conclusions. Some may wonder why the air goes faster over the top of the wing and this is where the popular explanation of lift falls apart.
In order to explain why the air goes faster over the top of the wing, many have resorted to the geometric argument that the distance the air must travel is directly related to its speed. The usual claim is that when the air separates at the leading edge, the part that goes over the top must converge at the trailing edge with the part that goes under the bottom. This is the so-called "principle of equal transit times".
As discussed by Gale Craig (Stop Abusing Bernoulli! How Airplanes Really Fly., Regenerative Press, Anderson, Indiana, 1997), let us assume that this argument were true. The average speeds of the air over and under the wing are easily determined because we can measure the distances and thus the speeds can be calculated. From Bernoulli’s principle, we can then determine the pressure forces and thus lift. If we do a simple calculation we would find that in order to generate the required lift for a typical small airplane, the distance over the top of the wing must be about 50% longer than under the bottom. Figure 1 shows what such an airfoil would look like. Now, imagine what a Boeing 747 wing would have to look like!
Fig 1 Shape of wing predicted by principle of equal transit time.
If we look at the wing of a typical small plane, which has a top surface that is 1.5 - 2.5% longer than the bottom, we discover that a Cessna 172 would have to fly at over 400 mph to generate enough lift. Clearly, something in this description of lift is flawed.
But, who says the separated air must meet at the trailing edge at the same time? Figure 2 shows the airflow over a wing in a simulated wind tunnel. In the simulation, colored smoke is introduced periodically. One can see that the air that goes over the top of the wing gets to the trailing edge considerably before the air that goes under the wing. In fact, close inspection shows that the air going under the wing is slowed down from the "free-stream" velocity of the air. So much for the principle of equal transit times.
Fig 2 Simulation of the airflow over a wing in a wind tunnel,
with colored "smoke" to show the acceleration and deceleration of the air.
The popular explanation also implies that inverted flight is impossible. It certainly does not address acrobatic airplanes, with symmetric wings (the top and bottom surfaces are the same shape), or how a wing adjusts for the great changes in load such as when pulling out of a dive or in a steep turn?
So, why has the popular explanation prevailed for so long? One answer is that the Bernoulli principle is easy to understand. There is nothing wrong with the Bernoulli principle, or with the statement that the air goes faster over the top of the wing. But, as the above discussion suggests, our understanding is not complete with this explanation. The problem is that we are missing a vital piece when we apply Bernoulli’s principle. We can calculate the pressures around the wing if we know the speed of the air over and under the wing, but how do we determine the speed?
Another fundamental shortcoming of the popular explanation is that it ignores the work that is done. Lift requires power (which is work per time). As will be seen later, an understanding of power is key to the understanding of many of the interesting phenomena of lift.
Newton’s laws and lift
So, how does a wing generate lift? To begin to understand lift we must return to high school physics and review Newton’s first and third laws. (We will introduce Newton’s second law a little later.) Newton’s first law states a body at rest will remain at rest, or a body in motion will continue in straight-line motion unless subjected to an external applied force. That means, if one sees a bend in the flow of air, or if air originally at rest is accelerated into motion, there is a force acting on it. Newton’s third law states that for every action there is an equal and opposite reaction. As an example, an object sitting on a table exerts a force on the table (its weight) and the table puts an equal and opposite force on the object to hold it up. In order to generate lift a wing must do something to the air. What the wing does to the air is the action while lift is the reaction.
Let’s compare two figures used to show streams of air (streamlines) over a wing. In figure 3 the air comes straight at the wing, bends around it, and then leaves straight behind the wing. We have all seen similar pictures, even in flight manuals. But, the air leaves the wing exactly as it appeared ahead of the wing. There is no net action on the air so there can be no lift! Figure 4 shows the streamlines, as they should be drawn. The air passes over the wing and is bent down. The bending of the air is the action. The reaction is the lift on the wing.
Fig 3 Common depiction of airflow over a wing. This wing has no lift.
Fig 4 True airflow over a wing with lift, showing upwash and downwash.
The wing as a pump
As Newton’s laws suggests, the wing must change something of the air to get lift. Changes in the air’s momentum will result in forces on the wing. To generate lift a wing must divert air down; lots of air.
The lift of a wing is equal to the change in momentum of the air it is diverting down. Momentum is the product of mass and velocity. The lift of a wing is proportional to the amount of air diverted down times the downward velocity of that air. Its that simple. (Here we have used an alternate form of Newton’s second law that relates the acceleration of an object to its mass and to the force on it; F=ma) For more lift the wing can either divert more air (mass) or increase its downward velocity. This downward velocity behind the wing is called "downwash". Figure 5 shows how the downwash appears to the pilot (or in a wind tunnel). The figure also shows how the downwash appears to an observer on the ground watching the wing go by. To the pilot the air is coming off the wing at roughly the angle of attack. To the observer on the ground, if he or she could see the air, it would be coming off the wing almost vertically. The greater the angle of attack, the greater the vertical velocity. Likewise, for the same angle of attack, the greater the speed of the wing the greater the vertical velocity. Both the increase in the speed and the increase of the angle of attack increase the length of the vertical arrow. It is this vertical velocity that gives the wing lift.
Fig 5 How downwash appears to a pilot and to an observer on the ground.
As stated, an observer on the ground would see the air going almost straight down behind the plane. This can be demonstrated by observing the tight column of air behind a propeller, a household fan, or under the rotors of a helicopter; all of which are rotating wings. If the air were coming off the blades at an angle the air would produce a cone rather than a tight column. If a plane were to fly over a very large scale, the scale would register the weight of the plane.
If we estimate that the average vertical component of the downwash of a Cessna 172 traveling at 110 knots to be about 9 knots, then to generate the needed 2,300 lbs of lift the wing pumps a whopping 2.5 ton/sec of air! In fact, as will be discussed later, this estimate may be as much as a factor of two too low. The amount of air pumped down for a Boeing 747 to create lift for its roughly 800,000 pounds takeoff weight is incredible indeed.
Pumping, or diverting, so much air down is a strong argument against lift being just a surface effect as implied by the popular explanation. In fact, in order to pump 2.5 ton/sec the wing of the Cessna 172 must accelerate all of the air within 9 feet above the wing. (Air weighs about 2 pounds per cubic yard at sea level.) Figure 6 illustrates the effect of the air being diverted down from a wing. A huge hole is punched through the fog by the downwash from the airplane that has just flown over it.
Fig 6 Downwash and wing vortices in the fog.
(Photographer Paul Bowen, courtesy of Cessna Aircraft, Co.)
So how does a thin wing divert so much air? When the air is bent around the top of the wing, it pulls on the air above it accelerating that air down, otherwise there would be voids in the air left above the wing. Air is pulled from above to prevent voids. This pulling causes the pressure to become lower above the wing. It is the acceleration of the air above the wing in the downward direction that gives lift. (Why the wing bends the air with enough force to generate lift will be discussed in the next section.)
As seen in figure 4, a complication in the picture of a wing is the effect of "upwash" at the leading edge of the wing. As the wing moves along, air is not only diverted down at the rear of the wing, but air is pulled up at the leading edge. This upwash actually contributes to negative lift and more air must be diverted down to compensate for it. This will be discussed later when we consider ground effect.
Normally, one looks at the air flowing over the wing in the frame of reference of the wing. In other words, to the pilot the air is moving and the wing is standing still. We have already stated that an observer on the ground would see the air coming off the wing almost vertically. But what is the air doing above and below the wing? Figure 7 shows an instantaneous snapshot of how air molecules are moving as a wing passes by. Remember in this figure the air is initially at rest and it is the wing moving. Ahead of the leading edge, air is moving up (upwash). At the trailing edge, air is diverted down (downwash). Over the top the air is accelerated towards the trailing edge. Underneath, the air is accelerated forward slightly, if at all.
Fig 7 Direction of air movement around a wing
as seen by an observer on the ground.
In the mathematical aerodynamics description of lift this rotation of the air around the wing gives rise to the "bound vortex" or "circulation" model. The advent of this model, and the complicated mathematical manipulations associated with it, leads to the direct understanding of forces on a wing. But, the mathematics required typically takes students in aerodynamics some time to master.
One observation that can be made from figure 7 is that the top surface of the wing does much more to move the air than the bottom. So the top is the more critical surface. Thus, airplanes can carry external stores, such as drop tanks, under the wings but not on top where they would interfere with lift. That is also why wing struts under the wing are common but struts on the top of the wing have been historically rare. A strut, or any obstruction, on the top of the wing would interfere with the lift.
Air has viscosity
The natural question is "how does the wing divert the air down?" When a moving fluid, such as air or water, comes into contact with a curved surface it will try to follow that surface. To demonstrate this effect, hold a water glass horizontally under a faucet such that a small stream of water just touches the side of the glass. Instead of flowing straight down, the presence of the glass causes the water to wrap around the glass as is shown in figure 8. This tendency of fluids to follow a curved surface is known as the Coanda effect. From Newton’s first law we know that for the fluid to bend there must be a force acting on it. From Newton’s third law we know that the fluid must put an equal and opposite force on the object which caused the fluid to bend.
Fig 8 Coanda effect.
Why should a fluid follow a curved surface? The answer is viscosity; the resistance to flow which also gives the air a kind of "stickiness". Viscosity in air is very small but it is enough for the air molecules to want to stick to the surface. At the surface the relative velocity between the surface and the nearest air molecules is exactly zero. (That is why one cannot hose the dust off of a car and why there is dust on the backside of the fans in a wind tunnel.) Just above the surface the fluid has some small velocity. The farther one goes from the surface the faster the fluid is moving until the external velocity is reached (note that this occurs in less than an inch). Because the fluid near the surface has a change in velocity, the fluid flow is bent towards the surface. Unless the bend is too tight, the fluid will follow the surface. This volume of air around the wing that appears to be partially stuck to the wing is called the "boundary layer".
Lift as a function of angle of attack
There are many types of wing: conventional, symmetric, conventional in inverted flight, the early biplane wings that looked like warped boards, and even the proverbial "barn door". In all cases, the wing is forcing the air down, or more accurately pulling air down from above. What each of these wings have in common is an angle of attack with respect to the oncoming air. It is this angle of attack that is the primary parameter in determining lift. The inverted wing can be explained by its angle of attack, despite the apparent contradiction with the popular explanation involving the Bernoulli principle. A pilot adjusts the angle of attack to adjust the lift for the speed and load. The popular explanation of lift which focuses on the shape of the wing gives the pilot only the speed to adjust.
To better understand the role of the angle of attack it is useful to introduce an "effective" angle of attack, defined such that the angle of the wing to the oncoming air that gives zero lift is defined to be zero degrees. If one then changes the angle of attack both up and down one finds that the lift is proportional to the angle. Figure 9 shows the coefficient of lift (lift normalized for the size of the wing) for a typical wing as a function of the effective angle of attack. A similar lift versus angle of attack relationship is found for all wings, independent of their design. This is true for the wing of a 747 or a barn door. The role of the angle of attack is more important than the details of the airfoil’s shape in understanding lift.
Fig 9 Coefficient of lift versus the effective angle of attack.
Typically, the lift begins to decrease at an angle of attack of about 15 degrees. The forces necessary to bend the air to such a steep angle are greater than the viscosity of the air will support, and the air begins to separate from the wing. This separation of the airflow from the top of the wing is a stall.
The wing as air "scoop"
We now would like to introduce a new mental image of a wing. One is used to thinking of a wing as a thin blade that slices though the air and develops lift somewhat by magic. The new image that we would like you to adopt is that of the wing as a scoop diverting a certain amount of air from the horizontal to roughly the angle of attack, as depicted in figure 10. The scoop can be pictured as an invisible structure put on the wing at the factory. The length of the scoop is equal to the length of the wing and the height is somewhat related to the chord length (distance from the leading edge of the wing to the trailing edge). The amount of air intercepted by this scoop is proportional to the speed of the plane and the density of the air, and nothing else.
Fig 10 The wing as a scoop.
As stated before, the lift of a wing is proportional to the amount of air diverted down times the vertical velocity of that air. As a plane increases speed, the scoop diverted more air. Since the load on the wing, which is the weight of the plane, does not increase the vertical speed of the diverted air must be decreased proportionately. Thus, the angle of attack is reduced to maintain a constant lift. When the plane goes higher, the air becomes less dense so the scoop diverts less air for the same speed. Thus, to compensate the angle of attack must be increased. The concepts of this section will be used to understand lift in a way not possible with the popular explanation.
Lift requires power
When a plane passes overhead the formally still air ends up with a downward velocity. Thus, the air is left in motion after the plane leaves. The air has been given energy. Power is energy, or work, per time. So, lift must require power. This power is supplied by the airplane’s engine (or by gravity and thermals for a sailplane).
How much power will we need to fly? The power needed for lift is the work (energy) per unit time and so is proportional to the amount of air diverted down times the velocity squared of that diverted air. We have already stated that the lift of a wing is proportional to the amount of air diverted down times the downward velocity of that air. Thus, the power needed to lift the airplane is proportional to the load (or weight) times the vertical velocity of the air. If the speed of the plane is doubled the amount of air diverted down doubles. Thus the angle of attack must be reduced to give a vertical velocity that is half the original to give the same lift. The power required for lift has been cut in half. This shows that the power required for lift becomes less as the airplane's speed increases. In fact, we have shown that this power to create lift is proportional to one over the speed of the plane.
But, we all know that to go faster (in cruise) we must apply more power. So there must be more to power than the power required for lift. The power associated with lift, described above, is often called the "induced" power. Power is also needed to overcome what is called "parasitic" drag, which is the drag associated with moving the wheels, struts, antenna, etc. through the air. The energy the airplane imparts to an air molecule on impact is proportional to the speed squared. The number of molecules struck per time is proportional to the speed. Thus the parasitic power required to overcome parasitic drag increases as the speed cubed.
Figure 11 shows the power curves for induced power, parasitic power, and total power which is the sum of induced power and parasitic power. Again, the induced power goes as one over the speed and the parasitic power goes as the speed cubed. At low speed the power requirements of flight are dominated by the induced power. The slower one flies the less air is diverted and thus the angle of attack must be increased to maintain lift. Pilots practice flying on the "backside of the power curve" so that they recognizes that the angle of attack and the power required to stay in the air at very low speeds are considerable.
Fig 11 Power requirements versus speed.
At cruise, the power requirement is dominated by parasitic power. Since this goes as the speed cubed an increase in engine size gives one a faster rate of climb but does little to improve the cruise speed of the plane.
Since we now know how the power requirements vary with speed, we can understand drag, which is a force. Drag is simply power divided by speed. Figure 12 shows the induced, parasitic, and total drag as a function of speed. Here the induced drag varies as one over speed squared and parasitic drag varies as the speed squared. Taking a look at these curves one can deduce a few things about how airplanes are designed. Slower airplanes, such as gliders, are designed to minimize induced drag (or induced power), which dominates at lower speeds. Faster airplanes are more concerned with parasite drag (or parasitic power).
Fig 12 Drag versus speed.
Wing efficiency
At cruise, a non-negligible amount of the drag of a modern wing is induced drag. Parasitic drag, which dominates at cruise, of a Boeing 747 wing is only equivalent to that of a 1/2-inch cable of the same length. One might ask what effects the efficiency of a wing. We saw that the induced power of a wing is proportional to the vertical velocity of the air. If the length of a wing were to be doubled, the size of our scoop would also double, diverting twice as much air. So, for the same lift the vertical velocity (and thus the angle of attack) would have to be halved. Since the induced power is proportional to the vertical velocity of the air, it too is reduced by half. Thus, the lifting efficiency of a wing is proportional to one over the length of the wing. The longer the wing the less induced power required to produce the same lift, though this is achieved with and increase in parasitic drag. Low speed airplanes are effected more by induced drag than fast airplanes and so have longer wings. That is why sailplanes, which fly at low speeds, have such long wings. High-speed fighters, on the other hand, feel the effects of parasite drag more than our low speed trainers. Therefore, fast airplanes have shorter wings to lower parasite drag.
There is a misconception by some that lift does not require power. This comes from aeronautics in the study of the idealized theory of wing sections (airfoils). When dealing with an airfoil, the picture is actually that of a wing with infinite span. Since we have seen that the power necessary for lift is proportional to one over the length of the wing, a wing of infinite span does not require power for lift. If lift did not require power airplanes would have the same range full as they do empty, and helicopters could hover at any altitude and load. Best of all, propellers (which are rotating wings) would not require power to produce thrust. Unfortunately, we live in the real world where both lift and propulsion require power.
Power and wing loading
Let us now consider the relationship between wing loading and power. Does it take more power to fly more passengers and cargo? And, does loading affect stall speed? At a constant speed, if the wing loading is increased the vertical velocity must be increased to compensate. This is done by increasing the angle of attack. If the total weight of the airplane were doubled (say, in a 2g turn) the vertical velocity of the air is doubled to compensate for the increased wing loading. The induced power is proportional to the load times the vertical velocity of the diverted air, which have both doubled. Thus the induced power requirement has increased by a factor of four! The same thing would be true if the airplane’s weight were doubled by adding more fuel, etc.
One way to measure the total power is to look at the rate of fuel consumption. Figure 13 shows the fuel consumption versus gross weight for a large transport airplane traveling at a constant speed (obtained from actual data). Since the speed is constant the change in fuel consumption is due to the change in induced power. The data are fitted by a constant (parasitic power) and a term that goes as the load squared. This second term is just what was predicted in our Newtonian discussion of the effect of load on induced power.
Fig 13 Fuel consumption versus load for a large transport airplane
traveling at a constant speed.
The increase in the angle of attack with increased load has a downside other than just the need for more power. As shown in figure 9 a wing will eventually stall when the air can no longer follow the upper surface. That is, when the critical angle is reached. Figure 14 shows the angle of attack as a function of airspeed for a fixed load and for a 2-g turn. The angle of attack at which the plane stalls is constant and is not a function of wing loading. The stall speed increases as the square root of the load. Thus, increasing the load in a 2-g turn increases the speed at which the wing will stall by 40%. An increase in altitude will further increase the angle of attack in a 2-g turn. This is why pilots practice "accelerated stalls" which illustrates that an airplane can stall at any speed. For any speed there is a load that will induce a stall.
Fig 14 Angle of attack versus speed
for straight and level flight and for a 2-g turn.
Wing vortices
One might ask what the downwash from a wing looks like. The downwash comes off the wing as a sheet and is related to the details on the load distribution on the wing. Figure 15 shows, through condensation, the distribution of lift on an airplane during a high-g maneuver. From the figure one can see that the distribution of load changes from the root of the wing to the tip. Thus, the amount of air in the downwash must also change along the wing. The wing near the root is "scooping" up much more air than the tip. Since the root is diverting so much air the net effect is that the downwash sheet will begin to curl outward around itself, just as the air bends around the top of the wing because of the change in the velocity of the air. This is the wing vortex. The tightness of the curling of the wing vortex is proportional to the rate of change in lift along the wing. At the wing tip the lift must rapidly become zero causing the tightest curl. This is the wing tip vortex and is just a small (though often most visible) part of the wing vortex. Returning to figure 6 one can clearly see the development of the wing vortices in the downwash as well as the wing tip vortices.
Fig 15 Condensation showing the distribution of lift along a wing.
The wingtip vortices are also seen.
(from Patterns in the Sky, J.F. Campbell and J.R. Chambers, NASA SP-514.)
Winglets (those small vertical extensions on the tips of some wings) are used to improve the efficiency of the wing by increasing the effective length of the wing. The lift of a normal wing must go to zero at the tip because the bottom and the top communicate around the end. The winglets blocks this communication so the lift can extend farther out on the wing. Since the efficiency of a wing increases with length, this gives increased efficiency. One caveat is that winglet design is tricky and winglets can actually be detrimental if not properly designed.
Ground effect
Another common phenomenon that is misunderstood is that of ground effect. That is the increased efficiency of a wing when flying within a wing length of the ground. A low-wing airplane will experience a reduction in drag by 50% just before it touches down. There is a great deal of confusion about ground effect. Many pilots (and the FAA VFR Exam-O-Gram No. 47) mistakenly believe that ground effect is the result of air being compressed between the wing and the ground.
To understand ground effect it is necessary to have an understanding of upwash. For the pressures involved in low speed flight, air is considered to be non-compressible. When the air is accelerated over the top of the wing and down, it must be replaced. So some air must shift around the wing (below and forward, and then up) to compensate, similar to the flow of water around a canoe paddle when rowing. This is the cause of upwash.
As stated earlier, upwash is accelerating air in the wrong direction for lift. Thus a greater amount of downwash is necessary to compensate for the upwash as well as to provide the necessary lift. Thus more work is done and more power required. Near the ground the upwash is reduced because the ground inhibits the circulation of the air under the wing. So less downwash is necessary to provide the lift. The angle of attack is reduced and so is the induced power, making the wing more efficient.
Earlier, we estimated that a Cessna 172 flying at 110 knots must divert about 2.5 ton/sec to provide lift. In our calculations we neglected the upwash. From the magnitude of ground effect, it is clear that the amount of air diverted is probably more like 5 ton/sec.
Conclusions
Let us review what we have learned and get some idea of how the physical description has given us a greater ability to understand flight. First what have we learned:
The amount of air diverted by the wing is proportional to the speed of the wing and the air density.
The vertical velocity of the diverted air is proportional to the speed of the wing and the angle of attack.
The lift is proportional to the amount of air diverted times the vertical velocity of the air.
The power needed for lift is proportional to the lift times the vertical velocity of the air.
Now let us look at some situations from the physical point of view and from the perspective of the popular explanation.
The plane’s speed is reduced. The physical view says that the amount of air diverted is reduced so the angle of attack is increased to compensate. The power needed for lift is also increased. The popular explanation cannot address this.
The load of the plane is increased. The physical view says that the amount of air diverted is the same but the angle of attack must be increased to give additional lift. The power needed for lift has also increased. Again, the popular explanation cannot address this.
A plane flies upside down. The physical view has no problem with this. The plane adjusts the angle of attack of the inverted wing to give the desired lift. The popular explanation implies that inverted flight is impossible.
As one can see, the popular explanation, which fixates on the shape of the wing, may satisfy many but it does not give one the tools to really understand flight. The physical description of lift is easy to understand and much more powerful.
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The preceding is an article by David Anderson, Fermi National Accelerator Laboratory, and Scott Eberhardt, Department of Aeronautics and Astronautics, University of Washington. The authors have given ALLSTAR permission to present this article on the ALLSTAR website.

[Havasu Cig]

Like Ron said, it isn't a tunnel. And "more hull" is relative. More running length? Yes. More depth? No. With our wider, flatter and longer running surface, combined with the several thousand pound weight loss due to construction methods we not only draft less water at rest, but far less at cruise. Our wetted surface is right around 2" at 20mph or so and 10" at rest.
Shorter, deeper running lengths are terrible for efficiency. The longer and flatter you can use the water going under your boat the better. Problem is, most designs that do this are long v-bottoms. They are efficient, but lack stability and can chine walk easily without tabs.
As a hydro we are off to the side somewhere. But one promise, your basic "tunnel hull" boats don't work the way that you think they do. They definitely don't work the way the guy who designed them thinks they do. They work, but the west coast guys don't understand why.
Some east coast guys do though. That is why people who have imitated Peter Hledin's bottoms and tops are becoming successful out here these days.
If you are curious as to whether or not your boat is generating ANY aerodynamic lift, you can do a quick test to find out for yourself.
1) Do you have an open cockpit?
2) Do you have a bow rider?
If the answer is yes to either of these two... you are not using air for lift. And anyone who knows anything about basic aerodynamics is scratching their heads right now and realizing why.
If you are talking about lift as in an airfoil (wing) making lift you are right. A boat with an open cockpit or open bow would have to much air disturbance on the deck to generate any lift. Any pilot would know this.
Congrats by the way on the boat. I think it is great to see someone on the West Coast pushing the limits when it comes to lay-up. With the numbers I am getting with my Skater I can tell you that it is heads and shoulders above anything built out here in hull efficiency.
Last weekend with 3/4 tanks, full cooler, all the usual crap stuffed in the boat, and running up the gorge against a 1.5 mph current I made a 117 mph pass in front of Moabi (this was in about a quarter mile stretch starting at about 35 mph). The boat easily has 120 in it. Not bad for a 28' boat with O/B's. I think the West Coast definitely needs to catch up.

[Froggystyle]

I actually have the hard copy of that article from when it came out. Seminal work to be sure. It threw a lot of "facts" into a tailspin with regard to the "sucking" of the plane into the air, and definitely re-defined the manner in which wing theory is taught.
In any case, with a captured wing in ground effect that a tunnel hull presents, that theory doesn't work there either. There is just nowhere to go, and the air doesn't compress.
The best way to describe an un-burped tunnel hull is as a coffee can facing into the wind. Once the can is full of air, it doesn't start generating more pressure, it generates a far larger dead spot in front of it increasing frontal drag. The can makes an air "plug" that stops any more air from coming in and creates a buffet area in front that deflects air around the can and greatly increases drag.
Once burped (tunnels out of the water) you can start doing some stuff with air. Mostly generating higher and lower velocities inside of the tunnels themselves. These amount to higher and lower pressures in the tunnels, but would be greatly spoiled by the air/water boundry layer present in the rear of the tunnels.
Fact is, water is nearly 1000 times denser than air. If you had the two surfaces to choose from, the smart money goes into reducing the drag on the one that is 1000 times denser. That also makes it 1000 times more efficient at generating any forces, be it drag or lift via deflection (planing).
When hydrodynamic efficiency has reached it's acme, then it may be time to start using some air, but the first thought should be merely to reduce drag, not generate lift. Canopies, hard decks, enclosed cabins, wide open tunnel centers, slick scoops etc... all go a long way towards doing that. All are ruined by opening up the deck like in a bowrider or in a deckboat.
The primary force acting on a boat hull is hydrodynamic. We chose this one as our ally, and used lighter weight, more hydrodynamically efficient bottom design and nearly dragless propulsion to create a more efficient and better performing hull. This is one of the reasons that we are damn near planed at idle.
Back to your regularly scheduled diatribes... ;)

[Froggystyle]

If you are talking about lift as in an airfoil (wing) making lift you are right. A boat with an open cockpit or open bow would have to much air disturbance on the deck to generate any lift. Any pilot would know this.
Congrats by the way on the boat. I think it is great to see someone on the West Coast pushing the limits when it comes to lay-up. With the numbers I am getting with my Skater I can tell you that it is heads and shoulders above anything built out here in hull efficiency.
Last weekend with 3/4 tanks, full cooler, all the usual crap stuffed in the boat, and running up the gorge against a 1.5 mph current I made a 117 mph pass in front of Moabi (this was in about a quarter mile stretch starting at about 35 mph). The boat easily has 120 in it. Not bad for a 28' boat with O/B's. I think the West Coast definitely needs to catch up.
Not having seen your boat, I can only speculate based on what I know of Peter's designs. My guess is, at 115, the boat was riding very flat, very smooth and pulling very little draft but wet pretty far forward. Correct?
BTW... not to bag on what I would consider one of the premier brands in high performance boating and a real trend-setter, but to express how powerful the resin infusion process is when combined with a linear foam core, I bet our 27' deckboat with a twin turbo intercooled big block, huge stereo, full interior for 14, drop down ramp and twin drives weighs less than your 28 with twins outboards (lightest setup you can get in the lightest boat on the market). And your boat is thousands of pounds lighter than a 28 Conquest or Magic equipped like ours.
Peter is looking into infusion right now. So is Randy from MTI. It is without a doubt the way of the future. Imagine your boat 1000# lighter.
I heard salesmen talking about one brand being better than another because it was heavier. We have a long way to go out here...

[Mandelon]

From the at rest ride height in the pics, I thought that Trident was on plane while still sitting on the dock.... :cool:

[Froggystyle]

From the at rest ride height in the pics, I thought that Trident was on plane while still sitting on the dock.... :cool:
I know the feeling. When you nail this thing there is zero sense of rolling over. It just starts moving faster. No bowrise, no "rope cut" feeling once on plane... it is just there.

[cola]

This thread is what ***boat needs more of. Thanks for the info. guys. :cool:
Mike

[weekendwarrior]

Yep... Hence the hydro. The primary running surface and weight supporter on the boat is the rear of the center sponson. The side sponsons stabilize the boat, provide floatation and displacement at rest and the inside edge provides a turning surface for the jet to work with. Additionally, the outside sponson (relative to turn) has a pronounced lifting strake to assist in the inside roll during maneuvers.
Once we had a couple of initial setup issues taken care of after the first voyage, we haven't burped the jet since. Plus, the hull made a big day on Parker seem like a small day at San V.
What is the actual definition of a hydroplane?

[Froggystyle]

What is the actual definition of a hydroplane?
Hydroplane Pronunciation: [hi-dro-plane] • (noun) A boat designed so that much of the hull lifts out of the water at high speeds; therefore much the boat skims over the water rather than through it. Usually refers to a particular type, style and class of boat used for high speed racing.

[weekendwarrior]

Hydroplane Pronunciation: [hi-dro-plane] • (noun) A boat designed so that much of the hull lifts out of the water at high speeds; therefore much the boat skims over the water rather than through it. Usually refers to a particular type, style and class of boat used for high speed racing.
Cool, so there could be more than one kind of hydro. Thanks, I didn't know.

[RiverDave]

For comparison...Jimmy's 28' Conquest had a Merc 575SCi and ran 90+ MPH no problem. Pulling a fat ass on a single competition ski? No problem.
:jawdrop:
90+ with a 575?
I test drove a conquest with a DPX 600 in it (counter rotating props) and it struggled to get on plane, but ran into the 80's (never did get a real good look at the speedo so I couldn't tell you exactly) How's this guy pulling 90's out of a 575?
RD

[RiverDave]

I actually have the hard copy of that article from when it came out. Seminal work to be sure. It threw a lot of "facts" into a tailspin with regard to the "sucking" of the plane into the air, and definitely re-defined the manner in which wing theory is taught.
In any case, with a captured wing in ground effect that a tunnel hull presents, that theory doesn't work there either. There is just nowhere to go, and the air doesn't compress.
The best way to describe an un-burped tunnel hull is as a coffee can facing into the wind. Once the can is full of air, it doesn't start generating more pressure, it generates a far larger dead spot in front of it increasing frontal drag. The can makes an air "plug" that stops any more air from coming in and creates a buffet area in front that deflects air around the can and greatly increases drag.
Once burped (tunnels out of the water) you can start doing some stuff with air. Mostly generating higher and lower velocities inside of the tunnels themselves. These amount to higher and lower pressures in the tunnels, but would be greatly spoiled by the air/water boundry layer present in the rear of the tunnels.
Fact is, water is nearly 1000 times denser than air. If you had the two surfaces to choose from, the smart money goes into reducing the drag on the one that is 1000 times denser. That also makes it 1000 times more efficient at generating any forces, be it drag or lift via deflection (planing).
When hydrodynamic efficiency has reached it's acme, then it may be time to start using some air, but the first thought should be merely to reduce drag, not generate lift. Canopies, hard decks, enclosed cabins, wide open tunnel centers, slick scoops etc... all go a long way towards doing that. All are ruined by opening up the deck like in a bowrider or in a deckboat.
The primary force acting on a boat hull is hydrodynamic. We chose this one as our ally, and used lighter weight, more hydrodynamically efficient bottom design and nearly dragless propulsion to create a more efficient and better performing hull. This is one of the reasons that we are damn near planed at idle.
Back to your regularly scheduled diatribes... ;)
I am half ass tempted to build a test fixture (relatively simple to do) to either prove or disprove this theory..
I don't believe that the air doesn't "compress" though.. As stated here.
The best way to describe an un-burped tunnel hull is as a coffee can facing into the wind. Once the can is full of air, it doesn't start generating more pressure, it generates a far larger dead spot in front of it increasing frontal drag. The can makes an air "plug" that stops any more air from coming in and creates a buffet area in front that deflects air around the can and greatly increases drag.
Point in fact, I'm fairly sure this is exactly how a pitot tube in an airplane measure air speed. Que no? I was under the impression that it Works sort of similar to a pick up tube for a marine speedo? The Higher the air pressure against a diaphram with a spring, the more it moves, to reflect a guage reading? If the air didn't "compress" in the "tunnel/tube" of a pitot tube of an airplane, and in fact just created a "air plug" (which I am not denying happens, but I still suggest there is pressure built) then the air speed indicator would always read zero? Unless by chance I have it wrong, and pitot tubes are "burped" (to Steal Wes's terminology there since it seems to fit) and they are measuring air passing through a tube via a turbine meter of some sort?
I'm not up to date on my readings with regards to how gasses react in various situations.. But the common sense aspect of things is telling me otherwise?
I am curious to know if any mfg's ever put PSI guages in the tunnels to try and measure what is commonly referred to as "tunnel compression."
RD

[Sleek-Jet]

I am half ass tempted to build a test fixture (relatively simple to do) to either prove or disprove this theory..
I don't believe that the air doesn't "compress" though.. As stated here.
Point in fact, I'm fairly sure this is exactly how a pitot tube in an airplane measure air speed. Que no? I was under the impression that it Works sort of similar to a pick up tube for a marine speedo? The Higher the air pressure against a diaphram with a spring, the more it moves, to reflect a guage reading? ...
RD
Unless someone has writen an new text in the last few years, yes Dave, that is how an airspeed indicator/pitot tube works.
A pitot system measures the difference between the static pressure and dynamic pressure.

[RiverDave]

Unless someone has writen an new text in the last few years, yes Dave, that is how an airspeed indicator/pitot tube works.
An pitot system measures the difference between the static pressure and dynamic pressure.
Well then wouldn't that in itself disprove this statement?
The best way to describe an un-burped tunnel hull is as a coffee can facing into the wind. Once the can is full of air, it doesn't start generating more pressure, it generates a far larger dead spot in front of it increasing frontal drag. The can makes an air "plug" that stops any more air from coming in and creates a buffet area in front that deflects air around the can and greatly increases drag.
Again don't get me wrong becuase I think alot of what Wes is saying is right, I just think he's wrong on this particular point.
RD

[Sleek-Jet]

Again don't get me wrong becuase I think alot of what Wes is saying is right, I just think he's wrong on this particular point.
RD
Agreed, but I think I see where he's going. From what I'm reading into it, forcing the air into an enclosed space would induce drag by causing air to spill around the front of the hull, canceling any benefit gained by lifting the boat out of the water by trapping the air underneath it. By "burping" the hull, the amount of air spilled around the front would be reduced, lowering drag.
It would be interesting to see the pressure differential on a tunnel hull at speed.

[Infomaniac]

Let me throw this out for discussion: Air does not compress at subsonic speeds. It's static pressure will increase or decrease, but it acts as an incompressible fluid when flowing through a duct or around objects at subsonic speeds.
Yea an aircraft airspeed indicator works off of differential pressure. Impact air pressure from the pitot tube and static pressure measured 90 degrees to the pitot tube. Impact air being the force created by the air due to it's density and speed. It can't use pitot tube pressure alone because air pressure is not the same from sea level to operating altitude. So the static pressure must be measured and it is the difference in pitot pressure and static pressure that gives airspeed.
I can't see a typical tunnel hull boat using airfoil lift at all. Every tunnel I have ever looked at converges from bow to stern. Air flowing through a convergent duct increases in speed and decreases in static pressure. So how is a decreased pressure under the boat going to create lift?
My personal theory of how a tunnel boat creates lift is the bottom of the boat is utilizing "impact lift". The same principal that happens when you stick your hand out the window of the car and tilt it upward. The tunnels merely "allow" air to flow under the boat. And the converging duct merely purges the air from under the boat to reduce drag. After the hull has used the impact lift, the air has to be scavenged so it does not just pile up and create drag.
I can see the coffee can thing. The air in the can will be as dense as it can possibly be, but not be compressed. It is gonna take mechanical help to compress air at subsonic speeds.
But hey, just my opinion. :D

[ECeptor]

It would be interesting to see the pressure differential on a tunnel hull at speed.
I think I read somewhere that Callan's new 50'er has something like +50 pressure measurements insturmented and recorded to help understand the boat performance.
Living and working in an aircraft dominated city (Wichita), I bet there are a few boys in town that could make a boat truly fly!
I've wondered why there are not more active controls on a boat to change surfaces based upon speed, pitch, etc...would be easy to do with a simple computer on board.

[Sleek-Jet]

My personal theory of how a tunnel boat creates lift is the bottom of the boat is utilizing "impact lift". The same principal that happens when you stick your hand out the window of the car and tilt it upward. The tunnels merely "allow" air to flow under the boat. And the converging duct merely purges the air from under the boat to reduce drag. After the hull has used the impact lift, the air has to be scavenged so it does not just pile up and create drag.
I can see the coffee can thing. The air in the can will be as dense as it can possibly be, but not be compressed. It is gonna take mechanical help to compress air at subsonic speeds.
But hey, just my opinion. :D
That's how I think of it too... the "old Barn roof in a tornado" theory of flight...

[Havasu Hangin']

90+ with a 575?
I test drove a conquest with a DPX 600 in it (counter rotating props) and it struggled to get on plane, but ran into the 80's (never did get a real good look at the speedo so I couldn't tell you exactly) How's this guy pulling 90's out of a 575?
RD
I was on the boat- GPS speedo. Granted, when I was on it, it was into the wind with a slight chop, but he kept bumping the limiter.
I will say that it was not a comfortable ride- those deckboats are very windy.

[Froggystyle]

That's how I think of it too... the "old Barn roof in a tornado" theory of flight...
This is the single best description of impact lift I have ever heard.
I would like to use it in an update I am writing right now if you don't mind.

[Froggystyle]

BTW Jeff.... what are you doing up at 5:39???

[Infomaniac]

This is the single best description of impact lift I have ever heard.
I would like to use it in an update I am writing right now if you don't mind.
Thanks Sleek for stealing my glory. :cry: :cry:
LOL :rollside:

[Froggystyle]

Thanks Sleek for stealing my glory. :cry: :cry:
LOL :rollside:
For the record, I will be describing the "impact lift" theory as the "Munson theory of custom boat" lift henceforth...

[Havasu Hangin']

BTW Jeff.... what are you doing up at 5:39???
Sleep is not a luxury I can afford these days...
...come to think of it, I can't afford any luxury these days.
:cry:

[Charley]

Sleep is not a luxury I can afford these days...
...come to think of it, I can't afford any luxury these days.
:cry:
AMEN Brotha

[dicudmore]

AMEN Brotha
I second that also :cry:

[Sleek-Jet]

This is the single best description of impact lift I have ever heard.
I would like to use it in an update I am writing right now if you don't mind.
It certainly wasn't my idea... use it at your leisure...
Sorry Ron. :D

[RiverDave]

Very Good Thread, and very good reading!! :)
RD

[Froggystyle]

Very Good Thread, and very good reading!! :)
RD
Just wait until you see the next update...

[RiverDave]

Just wait until you see the next update...
I have been waiting patiently... I was starting to think you changed the name of Trident to Whipple or something..
RD

[Froggystyle]

I have been waiting patiently... I was starting to think you changed the name of Trident to Whipple or something..
RD
Hey now... just like the boat, great things take time.
We decided to hold off the update until the new site was done... Soon though...