Porpoising???

[TRIMMIN]

Took the boat out for the first time since a total restoration. Couldn"t get her over 5K as she would porpoise where ever I set the plate. Any ideas?

[GofastRacer]

Well, without any details it sounds like the usual power, gear and prop combo is not right???...

[TRIMMIN]

Boat is a 16.5 Biese with a 383 Stroker, 400/500tq. A rebuilt Hall Craft by Tom and I think he said the gears were 10's. Prop is a SS 3 blade 11X15? She would ride nice at 4K but after that it was not fun. This is my first V-drive.

[dmontzsta]

My first guess would be, not enough hp/tq to carry the nose? :)

[TRIMMIN]

In a 16.5? Two stacked 11gal tanks behind motor, one full.

[Moneypitt]

Well, without any details it sounds like the usual power, gear and prop combo is not right???...
Add: Short boat, steep strut angle........Prop tries to push the nose up, instead of forward. Motor has the poop to drive the nose higher in the water, but not enough to carry it there so it falls down, only to be pushed up again. I'm guessing here, but the combo will carry the nose as long as the boat is accelerating. It is when the motor goes over the top of the power curve, or levels out, that the nose falls......??? Right????.......MP

[thatguy]

I see it's your first V-Drive. Got my first one last month. Same deal. Bouncing, 18' Eliminator.
I'm starting to think it's a learning curve, Hey all you expert V-Drivers, anybody want to hold a driving clinic? I would pay. It's tough to sort it out when you don't know where to start.
Tommy :(

[GofastRacer]

Add: Short boat, steep strut angle........Prop tries to push the nose up, instead of forward. Motor has the poop to drive the nose higher in the water, but not enough to carry it there so it falls down, only to be pushed up again. I'm guessing here, but the combo will carry the nose as long as the boat is accelerating. It is when the motor goes over the top of the power curve, or levels out, that the nose falls......??? Right????.......MP
Yep, also motor is probably too far back and the weight of the fuel in the back don't help either!. And if I understand this right it's one of those old Biesemeyers?? and they were not made for speed to begin with, just a nice ski boat!..

[GofastRacer]

I see it's your first V-Drive. Got my first one last month. Same deal. Bouncing, 18' Eliminator.
I'm starting to think it's a learning curve, Hey all you expert V-Drivers, anybody want to hold a driving clinic? I would pay. It's tough to sort it out when you don't know where to start.
Tommy :(
Have you tried dropping a gear???

[FlatRat]

I see it's your first V-Drive. Got my first one last month. Same deal. Bouncing, 18' Eliminator.
I'm starting to think it's a learning curve, Hey all you expert V-Drivers, anybody want to hold a driving clinic? I would pay. It's tough to sort it out when you don't know where to start.
Tommy :(
Tommy,
this is the clinic.There's a lot of info here...some good.. most is great.Read,ask questions and you'll fine..:idea:

[TRIMMIN]

Gofast you are right it is a old ski boat, a '72. I'm really bumed if this is the case. I guess I could have bought a crate motor from Pep Boys and saved myself a lot of time and money if I only wanted to go 50mph. I feel like burning it now. Time to go hang myself.

[GofastRacer]

Nahhh, don't burn it just put it back together the way it's supposed to be and enjoy it for what it is, after all it is a classic!..

[dmontzsta]

any pics?

[TRIMMIN]

If I wanted a classic I should have got a wood Cris Craft, I work with wood real good. I'm sitting here thinking I just wasted a year of my time and a whole lot of money on a ski boat. I feel way stupid.

[TRIMMIN]

No pics, I'm to stupid to post them too. I'll try to get some up soon. This boat has to nice of a motor to only go 50. I don't have to tell you guys what I've gone through in the last year to get this boat where it's at, you know. She's brand new, including the trailer. I'm just sick.

[GofastRacer]

Ya know, I wouldn't feel too bad you're not the first one to do that, and doubt very much that you're the last one!...
If you got any pics, send them to me and I'll post em for ya!.. racer025@cox.net

[dmontzsta]

Ya know, I wouldn't feel too bad you're not the first one to do that, and doubt very much that you're the last one!...
If you got any pics, send them to me and I'll post em for ya!.. racer025@cox.net
I agree, I went through the same exact thing. I think it is all apart of the experience. :)
I had a 64 LaveyCraft that ran 64mph, I wasnt happy. I had the floor re-done cause of some delamn issues, new pulley steering put in, new rudder, new prop, new gauges, new V-Drive split case (since it had a top loader), new 390 with mild work, N20 kit, new trailer tires all sorts of new goodies and only to get it together and run 72mph. I installed a overide pedal and was able to work my foot long enough to get some sort of a set, but it wasnt meant to be ran like that, so I sold it for $4k! Which you know isnt shit for what the little nuts and bolts in these things are worth. :)
I bought a boat with no motor that wasnt set up right, now I am going through it all again! This is the fun part though. :)

[Prop Rod]

TRIMMIN,
Are you sure you have enough down pedal/plate in the boat?
There is a fine line between not enough and too much, not enough can be a cause of porpoise and too much you will stuff the nose.
When you are cruizing along where is the water breaking under the boat?

[coolchange]

Welcome to the $25,000+, $7,000 boat club. Couple of key words here. First trip out,, after a year of " This is gonna be bitchen, I'll be the fastest guy on the lake". SS three blade That boat prolly needs a pretty small 2 blade. After 50-60 mph that three blade is throwin out the anchor. 10's sound about right. Now comes the part that seperates the flat bottom owners from the flat bottom guys. Prop massaging, prop to strut, move the motor an inch. Sounds like the potential to be a really nice boat but dont be disappointed cause it didn't run a hundred off the trailer. Like we all thought they would!

[TRIMMIN]

The boat does seem to ride wet. It was it's first time out so we were looking at a lot of things, and we had a motor issue so it went back on the trailer after about 45mins. I'll try again next weekend. We do have a down pedal that may need some fine tuning.

[Moneypitt]

The boat does seem to ride wet. It was it's first time out so we were looking at a lot of things, and we had a motor issue so it went back on the trailer after about 45mins. I'll try again next weekend. We do have a down pedal that may need some fine tuning.
OK....I have seen simular situations before. 1st thing to check is the cav plate conection to the pedal. The cav rod to bellcrank, (for lack of a better word) conection is critical. NO PLAY!! Have a couple of buddies try to hold the plate up and push the pedal down. Does the bellcrank move on the cav plate shaft? Alot of the bellcranks were aluminum and the keyways get eaten up and sloppy on the shaft. It all looks good until you're actually on the water. The ideal position of the plate is straight with the bottom of the boat while going across the water. 2nd, Where is the plate set? (Before making any changes measure and record where the plate is NOW. That way you can always return to those numbers if you get way out of whack) While each boat is a little different, most will be set with the plate up a little. With the handle forward, plate up, using a straight edge, use feeler gauges to measure the height of the plate at 4 points, port end as close to the end as the flat part of the bottom allows, and the same for the far starboard end. Write these numbers down. Then check the center ends, again using a flat part of the bottom as a guide. The center ends should be equal to each other. Write this number down as well. As I said each boat set up will require fine tuning in this area. Some boats like a small "gull" in the center of each plate to allow air to escape, some boats work better without the gull. (Back to number 1, if there is any play in the entire mechanical conection these finite adjustments mean nothing)......With the plate set to a given starting point, click the handle back 1/2 way. Try it. Click it forward one click, backward one click etc etc, and see what seems to help. Try raising, lowering, the adjustments. An 1/8th of an inch is alot!!!!! Someone here, maybe Art, will relate a starting point. But remember each boat is a little different, even twin hulls will be a little different. 3rd, how far back of the strut is the prop?....Don't exceed 5/8ths to 3/4 of an inch, but you can add nickels between the prop shaft and the v drive output shaft,(inside the coupler) to move the prop back, giving it more leverage to carry the nose. (Our P/S boat has 5 nickels in there). Again, each boat is different and any changes need to be written down and tried to discover which changes helped, and which ones didn't. As you can see, very small changes can make a huge difference how the boat handles and performs. As Art mentioned the weight of the fuel could be hurting you. Try running with minimal fuel in the tank, see if it makes any difference. Try moving the battery forward or back a foot or two, try it....ONE CHANGE AT A TIME........Plan a day on the water for the sole purpose of dialing in the boat, not a day trip for the family. Make a change, try it, make another, try it. Ask someone with flatbottom experience in your area to tag along for a day of testing. Stay close to the ramp so people on the beach can see the effect the change made on the way the boat "looks"....Better? Good, so go a little further in that direction, try it again. If it keeps improving, keep going until the last change hurts it, then go back.......And yes, it may take 2, 3, or more water days to dial it in........Art, give him an idea where to set the plates, OK? AND REMEMBER, WRITE EVERY CHANGE YOU MAKE DOWN, AND ONE CHANGE AT A TIME... Also record RPMs and GPS speed results after each change. And most important, don't get discouraged, it will come around with a surprisingly small amount of dedicated effort.............Ray

[thatguy]

I have only been able to take mine out once and the lake (Shasta) was not smooth. Had the old lady in the boat also so did not want to get into trouble with her in the boat.
It's the purple 73' flat Rick King had on here.
He put the motor in it, 427, but never ran it so nobody really knew how it would ride. I think it is mostly plate adjustment since it went straight and flat w/ the plate all the way down. As soon as you lift it starts the porpoising. I only stayed in it for about 5-6 seconds at a time, rolling about 40-50 mph when I stabbed it.
I'll be able to do much better testing in a couple weeks when I get home. Am fairly sure I can get it figured out, if I don't crash first.
Tommy:) :)

[TRIMMIN]

Thanks for the post Ray.Like Art says the boat really isn't a speed hull so I kind of wasted my time with the old girl. But on another note you are right about the bellcrank being aluminum and it is sloppy. This will be first on the list. Then I will tighten up the rest of the system and start some plate adjustments. I just didn't realize that everything needs to be fine tuned so much on these boats. I straight edged the plate to the bottom and thought I was in pretty good shape. Guess I was way wrong. The prop is about 11/16 from the strut so I may be good there. Thank for getting me looking at the rest of the system.

[VDRIVERACING]

Sounds like you're getting the "idea". Tuning the handling of these boats is a process, a continual one. But, not huge differences after you first get it in the ballpark. And....they are such a rush it's worth the effort. I'm not a guru like some of these other guys, but I am a student of them. I can say with certainty, that problems like you're having are usually not complicated mysteries, although it may feel like it at times. It usually turns out to be basic, and minimal, adjustments.
Recently, I changed the gears in my boat from 29's to 22's. I had the boat dialed in just right with the 29's, and with the 22's it turned absolutley evil; practically uncontrollable. Nose up, nose falling too fast, wanted to go every direction but straight. Joey Cucci and Dennis Rankin came over and reset the plates, and it was well mannered once again; just like that. It still requires different responses from me to drive(because I "changed" something--the gears), but it's under control now. The moral of the story is that these boats can seem hopeless, and a few well place adjustments can dial 'em right in. Hang in there buddy!

[GofastRacer]

This is one sweet piece, you did one heck of a job on it and you should be proud as hell not feeling bad about it, you have one of the "nicest" ski boats out there so keep it that way!.. Now go out and get a hot rod!..
http://www.***boat.com/forums/attachment.php?attachmentid=30260&stc=1&d=1178506328
http://www.***boat.com/forums/attachment.php?attachmentid=30261&stc=1&d=1178506328
http://www.***boat.com/forums/attachment.php?attachmentid=30262&stc=1&d=1178506328
http://www.***boat.com/forums/attachment.php?attachmentid=30263&stc=1&d=1178506328

[dmontzsta]

That is a VERY cool old school flatty. There is nothing wrong with that at all, I would keep that sucker and run it all day long.
Buy another boat on the side if you want to go really fast. :)

[Marty Gras]

Please post all of your specs and measurements. Is the prop from Dallas? or Tom? Menkens? When after all of the guys here are done, (trying to guide you) contact me and drag it out Havasu. I'll straighten it out as long as your checkbook is in gear. HA HA, it's just a V-drive boat! PS, do you have actual dyno figures/sheet on the motor? It would help.

[thatguy]

Here's mine. And that is a hell of a job you did on your boat. It looks better (much better) than new!
Tommy