setup questions

[tahitijet]

Ok I took the boat out today for the first time after adding a split bowl, droop, ride plate and 2* wedge.. I spoke with Jack at MPD who gave me some pointers for setting a starting point on the rideplate and wedge. I ended up at 2* up wedge and I think (I don't remember off hand) at 5* up in relation to the keel on the ride plate
The bottom has been blueprinted and pump setback as well as a backcut shoe. It was a bit hard to tell as the water wasn't to good but here is what i noticed.
First thing i noticed was the boat had a whole lot more bow rise and took much longer to get on plane.. Is this typical with a droop? This was with the diverter in full down.
There seemed to be alot of feedback (left hand preasure) on the steering wheel like something on the diverter was dragging and making me put right imput in the wheel to stay straight. What is causing this?
Before these changes the boat had a mild porpoise above 70mph that could be tuned out by the diverter.. Now it has a low speed porpoise that you can't fully get rid of even with full down diverter.
Anyone have any input on these items? I'm assuming I should start by either droping the ride plate or flipping the wedge??? Im thinking either one would help with bow rise and planeing, and at least give me some more down diverter as i'm thinking full up may be way to much up. but i'm thinking that by dropping the plate it might free up the steering?
just wondering where to start adjusting from here.
thanks

[Ken F]

I believe I would start by dropping your rideplate to about 2 degrees above keel.
To me, your low speed porpoise and bowrise would be indicitative of the rideplate being too high. (allowing the boat to "rock" back and forth from the hull to the rideplate.)
I don't think your 2 degree wedge in your droop is going to cause any of your problems mentioned other than possibly the steering problem. It could be that with the droop you are now dragging your divirter. (?) With the divirter on there, you should be able to overcome/adjust past any thrust angle problem.
Good luck, I'm sure someone who is a little smarter than I will chime in.
Ken F

[Taylorman]

Im having the steering pull problem like you. I had someone drive for me this weekend and i looked at the pump. I could not see anything dragging in the water that would cause the steering problem. My boat will turn right if i let go of the steering wheel. I can't figure out whats causing this.
Kevin

[texas-19]

taylorman,
If you are looking at the rideplate from the rear,could the plate be lower on the right side than the left.That would cause it to turn right.Try putting an extra washer on the left side of the ride plate under the rear bracket and see what that does.
Tahitijet,I agree with Ken,sounds like the rideplate is too high but i would lower it 1 degree at a time until i was happy with it.When the bow goes up the nozzle will drag until you are up on plane,and maybe with that much ride plate angle the nozzle is still dragging even on plane.Thats my experience anyway.

[Squirtcha?]

I'd agree with all that mentioned the rideplate angle being too great and causing the porpoise.
As for the steering (pulling) issue............Here's what I found with mine this winter when I flipped it over.
Although the rideplate has holes drilled in it and the bolts fit relatively tight, I found that my rideplate was actually cocked to one side a bit (speaking about the four holes that attach it to the shoe). There's just enough play in the holes that you have to check to make sure the rideplate is square to the back of the shoe (and boat). Mine pulled like a mad mogator until I noticed this and corrected it. I also had to grind a little material off the cradle so I could get the rideplate moved over to where it needed to be. The stiffners were making contact with the cradle before I did this.
When the boat was on the trailer it was difficult to notice. Now that I know it's like that, I check it for squareness with it's mating surface on the back of the shoe to see if the gap is even all the way across. You'd be surprised as to how much you can move the plate back and forth prior to tightening the hardware down all the way.

[Taylorman]

Thanks Dan, i'll have to check that. Ive been told to stand behind the boat about 20 feet to see if the ride plate is level relative to the boat. It appears to be. Ive not checked for ride plate being square.
Just to clarify, your ride was pushed left or right, not one side being lower than the other?
I need to go home and check that.
So how did you correct the problem? I guess you would have to remove the bolts from the craddle, square the plate to the boat and redrill the craddle holes then tighted the plate to the shoe?

[tahitijet]

thanks for the input guys.. one other thing i noticed was the pull was much harder with the diverter up then down.
The boat carried the bow higher then usuall so i figured it was something either with the plate or wedge.. I'll try the plate but just curious what effect would flipping the wedge to 2* down would have?
thanks

[victorfb]

i had that same low speed porpoise when i had the droop with no wedge. i added a 2 degree up wedge which lifted the thrust line and it went away. i used to have to run with the diverter fulldown and dragging to get rid of the porpoise. now with the wedge it rides real nice. if i had a three degree id try it but with my set up now it seems to work real well with the diverter throwing a 2' maybe 3' high roost. my ride plate is set at 4.5 degrees up from keel line which may need to come down a degree. this is an 18' rogers hull and all hulls act differantly to changes and set ups, you just have to play with it. good luck.

[Squirtin Thunder]

I have tried all above, they all had small efects on ride and porpise.I tried the droop with no wedge @ 4* up plate. It took full of down, on the diverter, to get the boat to ride OK. Then put 2* up and it got worse. I tried 2* down wedge then went back to no wedge and less plate up, 3*. I was able to do 1* at a time because of my set-up design, turnbuckles. Still shitty ride at low speed. Put 2* down wedge, 2* up on the plate, abit better. Went with 4* down and 1* up plate, ride is good at low speed and real good in chop. It also pulls like a rapped ape all the way up to top speed now. Lower thrust angle, less squat, means less drag. Also the boat pops up on plate extreamly quick.

[Squirtcha?]

Thanks Dan, i'll have to check that. Ive been told to stand behind the boat about 20 feet to see if the ride plate is level relative to the boat. It appears to be. Ive not checked for ride plate being square.
Just to clarify, your ride was pushed left or right, not one side being lower than the other?
Mine was not one side higher than the other, but angled to the right side of the boat, causing the boat to pull left HARD.
So how did you correct the problem? I guess you would have to remove the bolts from the craddle, square the plate to the boat and redrill the craddle holes then tighted the plate to the shoe?
I didn't redrill the holes in the cradle, I just used a die grinder and hogged em out a little (elongated them side to side). I was a little concerned about doing that due to all the pressure on the plate, but it hasn't been an issue. I thought it might be possible for it to shift back to it's original spot, but as long as everything's tight it seems to work out. The adjustment was very small and made a very big difference in handling.
Like I mentioned earlier, I did have to remove some material from the cradle because the rideplate stiffners would contact the cradle before the plate would line up properly. Just took a 4" grinder to the cradle and removed about 1/8" of material to allow for the lateral adjustment.
thanks for the input guys.. one other thing i noticed was the pull was much harder with the diverter up then down.
My symptoms exactly. With full diverter up it would about wrench the steering wheel out of your hands. Amazing how such a small adjustment, can make such a huge difference.

[LVjetboy]

"I'll try the plate but just curious what effect would flipping the wedge to 2* down...have?"
Launch: A droop lowered thrust line may cause more bow rise on launch, and the 2 degree up wedge also gives you 2 degrees less nozzle trim control. Flipping from 2 deg up to 2 deg down...you got 4 degrees more nozzle down trim. Nozzle trim controls bow rise better than plate angle at these slow speeds.
Proposing: A combination of diverter and plate trim control. Thrust line height also changes with wedge or droop, but I'm not sure thrust height affects low speed or cruise proposing as much as trim control. Diverter effectiveness, or nozzle trim is highly dependent on engine speed. With the throttle mashed like on launch you got maximum nozzle trim. But as you let up at slow speed or during cruise your nozzle trim becomes less effective. Say you see rough water and back off...nozzle down trim goes away making the jet more susceptible to porpoise. That throttle dependence (not to mention monkeying with your trim switch or handle during testing) also makes it harder to judge the best nozzle trim setup. Plate trim by comparison a bit easier and I think better for controlling rough water handling. Speed dependant and in most cases fixed...one less variable for the seat-of-the-pants meter.
Top Speed: If it’s a lake boat who cares? Trim for handling. :)
jer

[miketsouth]

LVjetboy
With the throttle mashed like on launch you got maximum nozzle trim. But as you let up at slow speed or during cruise your nozzle trim becomes less effective. Say you see rough water and back off...nozzle down trim goes away making the jet more susceptible to porpoise. jer
didnt think of this Jer. Makes sense. Thankyou.
I am trying to get away from having to have a diverter. I was thinking 'if i get it right, i dont need it' Well...thanks :frown:

[SmokinLowriderSS]

I'd never give up having a diverter on my lake boat
I have a Berk "F" with factory diverter. Trimmed down I get a great holeshot, use relatively little throttle starting a skiier or tube, and can controll porpose under choppy conditions. At a mid level, I can lighten the bow a bit for cruise or reduce the ammount of "mini-rooster" on the tube riders. Trimmed up lifts me a nice loooong showy tail, unloads my bow for flight, and immediately picks up my speed.
My Berk has a short factory ride plate "Cavitation Plate" which still has some effect on high-speed attitude & porposing. Too much up angle and she bounces, too little, she drags her hull.

[LVjetboy]

Miketsouth, just trying to put together thoughts or guidelines on how setup affects ride. Other than, "I did this or that go for x degrees" or, "every jet's different" yada yada...
Not that that's not true, or advice of those posting here's wrong. Just seems there's got to be some general principles (other than pure trial-and-error) that could help guide guys like me, you or tahitijet to a better setup for how we jet. You know, like that chapter in the book yet unpublished: "How to Performance Tune Your Jet Boat"
Like Smokin points out, there's lake boat benefits to nozzle trim. A few of those may be tuned out with setup for some jets not all. But for rough water porpoise control, I think I'd favor adjustable plate trim, be that ride or side plates, instead of nozzle trim. How do the circle jerks do it?
jer

[*BN*]

I have stayed away from this thread because... I would like to see a picture of the Boat to see if it is the same hull as mine. Mine was built out the back door of Tahiti when Schuster was in escrow selling Tahiti and before he started Hawaiian.
If is the same hull I have might have the magic since I was there with the same problem when I went from a 85mph ride to a 94mph with this hull. All it takes is a 1/16" in two spots.

[Squirtin Thunder]

Miketsouth, just trying to put together thoughts or guidelines on how setup affects ride. Other than, "I did this or that go for x degrees" or, "every jet's different" yada yada...
Not that that's not true, or advice of those posting here's wrong. Just seems there's got to be some general principles (other than pure trial-and-error) that could help guide guys like me, you or tahitijet to a better setup for how we jet. You know, like that chapter in the book yet unpublished: "How to Performance Tune Your Jet Boat"
Like Smokin points out, there's lake boat benefits to nozzle trim. A few of those may be tuned out with setup for some jets not all. But for rough water porpoise control, I think I'd favor adjustable plate trim, be that ride or side plates, instead of nozzle trim. How do the circle jerks do it?
jer
http://www2.***boat.com/image_center/data/520/2311Pict0172-med.jpg

[miketsouth]

I think I'd favor adjustable plate trim, be that ride or side plates
jer
My first jet was a shallow v. It NEEDED a diverter. I was constantaly adjusting it for speed and water conditions. All the way down for launch and all the way up for max speed. Varying inbetween for water conditions.
I now have a light pickle. Some will not accept this but at no time do i feel i NEED a diverter. Yes, the bow rises a little too high on launch for the "best" launch, but it is not excessive. No porpous at any weight or speed. I went pretty fast last year with 300-320 hp (70+) and maybe i could use some more nozzle trim at speed.
I was able to experiment with the ride plate. Funny how that thing works. Small changes make a difference, but there is only a small range where it is 'best' for me it is between 4* up and neutral. It would be nice to have a dynamic ride plate, if just for experiment.
I added some wedge and thought :sleeping: maybe not.
Time to work on the intake. I got a pressure gauge now and am running 30psi at 65mph. I am going to (if i figure out the way to change it) target 5-10psi at 65mph. My first 'victim' is going to be the shoe.

[UBFJ #454]

jer -
Not to start an argument ... In the case of up nozzle, I can agree with you when you said: "Launch: A droop lowered thrust line may cause more bow rise on launch". With down nozzle I would think the bow wouldn't rise as much ... more force levered about the CG.

[tahitijet]

BN. Heres a couple pics let me know if you want to see more
http://www.hotboatpics.com/pics/data/500/709P4110245-med.JPG
http://www.hotboatpics.com/pics/data/500/709P1010041-med.JPG
Jer and others The info so far has been great. thanks for the all the insight. I'm going to go out tomorrow drop the plate 1* and build some shims to go 1.5 and 2 more down as well as check the rideplate for square as squirtcha suugested.
now i'm wondering. if you had a ideal setup and the boat worked great with no wedge. What would the direct effects of adding up and down wedge be?
thanks

[*BN*]

check your PM's

[LVjetboy]

"Not to start an argument ... In the case of up nozzle, I can agree with you when you said: "Launch: A droop lowered thrust line may cause more bow rise on launch". With down nozzle I would think the bow wouldn't rise as much ... more force levered about the CG."
Bear, just talking about the affect of a lowered thrust line independent of diverter. But since you mentioned...I think you're right, droop extention will give the diverter more arm if diverters full down angle the same. But what about droop pin angle? I think pin angle (3-7 positive degrees) affects lever arm a heck of a lot more than a longitudinal extension because it changes diverter full down angle. In other words, given the distance between the nozzle and boat cg, changing the thrust angle will change arm more than keeping the same angle and extending the application point aft 7 inches. Does that make sense?
In fact, if we know the geometry and boat cg, it wouldn't be hard to calculate.
jer

[UBFJ #454]

jer -
Thanks for your comments and I agree ... We do have our measured CG and that's what we're starting to work on in terms of Lifting the back of our boat and potentially installing (in this boat ???) the capsule currently under construction.
jak

[tahitijet]

ok droped the plate down 1* to 4 up from keel. Boat got much better. pops up on plane now quick, stays on plane at slower rpm and vitrually no porpoise with diverter full down. diverter up any degree it has a gently porpoise at almost all speeds. I noticed now with the diverter down it doesn't carry the nose and actually feels like it's pushing it down now
so i gather that by lowering the plate it stopped the boat from carrying the nose so high and gave me a back a small amount of diverter control
I am going to drop the plate another 1/2* and take it back tomorrow.
The boat also pulls much less now I did however unbolt the plate and when i put it back on i used a straight egde to assure it was straight with the shoe so i'm not sure if it was the same problem as squirtcha? or if i was just direting the water off the plate directly onto the nozzle.
I'm still curious as to what effect the wedge really has.. I understand it changes thrust angle but what effect does it really have up or down? when I installed all this stuff i've read the droop added 8* up and the wedge 2* so i'm up 10* total from stock and intake was set in at 4* down so i should be at 6* up from the keel with the diverter in nuetral.. with the diverter having to be almost full down i'm sure thats more then 6* from nuetral???
thanks

[Squirtcha?]

Glad to hear your tuning is paying off. Just keep messing with it, and you'll eventually find the sweet spot.

[Squirtin Thunder]

ok droped the plate down 1* to 4 up from keel. Boat got much better. pops up on plane now quick, stays on plane at slower rpm and vitrually no porpoise with diverter full down. diverter up any degree it has a gently porpoise at almost all speeds. I noticed now with the diverter down it doesn't carry the nose and actually feels like it's pushing it down now
so i gather that by lowering the plate it stopped the boat from carrying the nose so high and gave me a back a small amount of diverter control
I am going to drop the plate another 1/2* and take it back tomorrow.
The boat also pulls much less now I did however unbolt the plate and when i put it back on i used a straight egde to assure it was straight with the shoe so i'm not sure if it was the same problem as squirtcha? or if i was just direting the water off the plate directly onto the nozzle.
I'm still curious as to what effect the wedge really has.. I understand it changes thrust angle but what effect does it really have up or down? when I installed all this stuff i've read the droop added 8* up and the wedge 2* so i'm up 10* total from stock and intake was set in at 4* down so i should be at 6* up from the keel with the diverter in nuetral.. with the diverter having to be almost full down i'm sure thats more then 6* from nuetral???
thanks
Just for S&G, turn the wedge over and put the big side up top. I am running mine at 4* down wedge, which gives me 3 1/2* up at neutral or center on the diverter. You will like it !!! I have put about 250 miles on my boat in the last two weekends. It is awesome, handles the chop very well, not to mention the three to four foot swells. My set up 4* wedge down and 1* up on the plate and with the lower center of thrust it will run 75 mph fully loaded. That includes 3 passengers, 13 gallons of extra gas, 22 gallons in the tanks, an anchor, two coolers, emergency tool bag, three foldup chairs and umbrellas, a beach blanket, two kids skis, all necessary boating floatation equipment, three fire extinquishers and a partridge in a pear tree.
And BTW, with the Edelbrock 750, I was getting 3.7 mpg, with that load !!!

[Taylorman]

So im still messing with mine to try to get it to stop pulling. I checked the ride plate and it appears to be square with the pump and shoe. I took my ride plate and shoe off and tried the stock ride plate that came with the e pump today. No luck, still has a slight right pull. Im going to a big get together in Houston in two weeks. There will be about twenty guys from the boards there. Maybe someone can see something i can't.
I may try the down wedge that squirt thunder suggested above.
Kevi

[Squirtin Thunder]

I may try the down wedge that squirt thunder suggested above.
Kevi
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