Is this normal for a jet?

[mevale]

I finally got the motor tuned and she is running great! When I get the boat out of hole and running I canÂ’t really control the boat the boat slides all over the place. Is this normal for a jet? The boat is 21Â’ day cruiser the pump has been completely been gone threw by MPD the pump has a loader, pre loader, bronze A impeller, droop and place diverter.
The motor is Ford 467 Blown running 600 hp give or take the best I seen is 63 mph. What can I do for the boat to run straight? It feels a bit unsafe at this moment especially when I hit some good rollers.
Thanks
Joe

[Lightning]

What type of hull is it. Sounds like you may have some issues with the bottom of the boat.

[Wicked Performance Boats]

Has somebody cut the 2 fins on the intake off? Budlight

[flat broke]

Could that boat be bow steering? In other words, the boat likes to "hunt" in different directions as the entry on the bow follows the changing contour of the water?
If it IS bow steering, check the back of the hull for hook which may cause it to run wet and drive the bow of the boat down.
If it's not bow steering and feels loose over certain water conditions, you may need to look into a turning fin (not a rudder). Additionally, when trying to turn a boat of that size, make sure you don't have it trimmed out a bunch with the diverter.
Good luck,
Chris

[mevale]

Has somebody cut the 2 fins on the intake off? Budlight
I still have the fins on my intake.
This what the boat look like before the mods of pump and motor at CBBB
http://www2.***boat.com/image_center/data/500/2143cbbb040278_1_.jpg

[mevale]

Could that boat be bow steering? In other words, the boat likes to "hunt" in different directions as the entry on the bow follows the changing contour of the water?
If it IS bow steering, check the back of the hull for hook which may cause it to run wet and drive the bow of the boat down.
If it's not bow steering and feels loose over certain water conditions, you may need to look into a turning fin (not a rudder). Additionally, when trying to turn a boat of that size, make sure you don't have it trimmed out a bunch with the diverter.
Good luck,
Chris
That is exactly what it feels like! Jack did say I have a hook. Does a hook affect this much when it comes to steering? I thought it only affect speed?

[Squirtin Thunder]

That is exactly what it feels like! Jack did say I have a hook. Does a hook affect this much when it comes to steering? I thought it only affect speed?
Joe,
A hook will affect every aspect of the handling. Now there are some ways to bandaid it for now. One is put some wedge to it. I would bet a 4* would be a bit drastic but would give you a starting point. Also you may just need to put some down wedge to it to creat more lift and a lower center of thrust. I have wedges here if you are coming out and want to try them.
Jim

[SmokinLowriderSS]

Seems to ba a lot of glass in the water at speed there, but it may be tough to try to carry the bow very high on a 21-footer. My 18-footer has no intake fins but tracks very straight flat out running quite bow-high. I do have a rudder on my Berk "F" pump but not much of it is in water with the roost up and at top speed. My suspicion would be bow-steer from the picture.

[mevale]

How do I fix bow-steer? I have not talked to Jack at MPD yet but when he had the boat and pump he did some measuring and he did say I did not need any wedge. Is a wedge a tuning tool or just a Band-Aid?
Joe
Ps That pic is from last year at CBBB whit no modifications
running 51 mph

[Duane HTP]

A boat like that loves a long Snoot with a 4 degree up steering pin axis.

[SoCalKev]

.. :jawdrop:

[SmokinLowriderSS]

Get the bow out of the water! :messedup: The bow doesn't steer worth a darn if it is in air! :D :D

[SmokinLowriderSS]

A wedge is a tuning tool, just as snoots, droop snoots, diverters, ride plates, and angled pin locations for the nozzle.

[Squirtin Thunder]

How do I fix bow-steer? I have not talked to Jack at MPD yet but when he had the boat and pump he did some measuring and he did say I did not need any wedge. Is a wedge a tuning tool or just a Band-Aid?
Joe
Ps That pic is from last year at CBBB whit no modifications
running 51 mph
Joe
It is only a bandaid in a case where it is compensating for something else. Yes wedges are tuning tools !!! I have rocker and with the droop I have to counter act the 7.5 up pin angle with a 4* wedge. But by wedging it it also creats more lift.
Jim

[flat broke]

The hook will keep the boat from lifting the bow. What happens is that everytime the boat starts to lift, the hook sucks to the water and pulls the nose down. The droop may be accentuating the problem by creating transom lift. You could try running the boat with just the diverter and a 4* wedge to see if that helps. Ultimately, if you are pursuing speed, the hook has to go. I had a very similar hull, but laid up by a different company, the boat had no less than .250" of hook up at least 2 feet from the transom. I grabbed my Spectra and never bothered to work with that hull much, but I know exactly how scary that sensation can be. The boat isn't much fun at all to drive like that.
Chris

[mevale]

[QUOTE=I know exactly how scary that sensation can be. The boat isn't much fun at all to drive like that.
Chris[/QUOTE]
I was at Parker this weekend for OP6C and the river was out of control and so was the boat with no where to go.

[flat broke]

Short of fixing the hook, you need to get the ass of the boat to sit down lower than the nose when on plane. Did the boat used to do this, or was it easier to drive with the old motor/pump setup? Was the droop on the old setup?
My thought is that you were going slower last year with the smaller/non blown engine, and the speeds you are now seeing are starting to accentuate a problem that was present all along, but not bad enough to get your full attention.
Take a day and get out to the lake (wide open space=more room for error with a poor handling boat) run the boat without the droop, playing with the diverter to see if you can trim the issue out at all with the droop removed from the equation. Next try running a 4* wedge with just the diverter and see if that allows you to run less trim and still keep the bow steer minimized. Then if that is working properly, find a way to get your hands on a straight snoot for testing and see how that goes. If you can't get a straight snoot, you could always use a bowl extension and the wedge. Basically just focus on hardware setups that don't create transom lift.
Additionally, if you have a shoe/rideplate setup and are running a large back cut on the shoe, you might want to look at a straight cut shoe to further reduce the amount of lift seen at the transom.
To answer an earlier question you had about the hook having this much influence on the steering. It's not that the hook is making it harder to steer, it is that the hook is driving the steeper part of the V in the front of the boat down into the water. The hull then tracks off whatever contour the V picks up and you aren't having a tough time steering, but rather spending all of your time counter steering to keep the boat on a straight course.
Chris

[mevale]

Short of fixing the hook, you need to get the ass of the boat to sit down lower than the nose when on plane. Did the boat used to do this, or was it easier to drive with the old motor/pump setup? Was the droop on the old setup?
My thought is that you were going slower last year with the smaller/non blown engine, and the speeds you are now seeing are starting to accentuate a problem that was present all along, but not bad enough to get your full attention.
Take a day and get out to the lake (wide open space=more room for error with a poor handling boat) run the boat without the droop, playing with the diverter to see if you can trim the issue out at all with the droop removed from the equation. Next try running a 4* wedge with just the diverter and see if that allows you to run less trim and still keep the bow steer minimized. Then if that is working properly, find a way to get your hands on a straight snoot for testing and see how that goes. If you can't get a straight snoot, you could always use a bowl extension and the wedge. Basically just focus on hardware setups that don't create transom lift.
Additionally, if you have a shoe/rideplate setup and are running a large back cut on the shoe, you might want to look at a straight cut shoe to further reduce the amount of lift seen at the transom.
To answer an earlier question you had about the hook having this much influence on the steering. It's not that the hook is making it harder to steer, it is that the hook is driving the steeper part of the V in the front of the boat down into the water. The hull then tracks off whatever contour the V picks up and you aren't having a tough time steering, but rather spending all of your time counter steering to keep the boat on a straight course.
Chris
WOW dude! Are you sure you where not on my boat when all this was happening? Your assumptions are correct I did not have any problems before the modifications. You know this last time I was at the Long Beach swamp meet I was talking to Jim Brock about my Porpoising and maybe getting some trim tabs. After talking to him I found out I was using the place diverter wrong. For example when I would get in to big chop I would raise PD and that would create the Porpoising so now I lower the PD when IÂ’m in some choppy water but now I get bow-steer. WTF IÂ’m confused!

[Red Horse]

You dont by chance have a fuel tank up front or batteries, something or things that are heavy. You want weight to be in the back. And if you have hook, it has to go. :cool:

[oldbuck40]

WOW dude! Are you sure you where not on my boat when all this was happening? Your assumptions are correct I did not have any problems before the modifications. You know this last time I was at the Long Beach swamp meet I was talking to Jim Brock about my Porpoising and maybe getting some trim tabs. After talking to him I found out I was using the place diverter wrong. For example when I would get in to big chop I would raise PD and that would create the Porpoising so now I lower the PD when IÂ’m in some choppy water but now I get bow-steer. WTF IÂ’m confused!read what you wrote! sounds to me like you are over doing it a little on the place diverter,and yes alot of boats will do this if you put it all the way down or all the way up! if your diverter is hydrolic then try not to put so much down in it and see what happens. a boat that size should run very well with the diverter flat level or slightly up position.

[flat broke]

WOW dude! Are you sure you where not on my boat when all this was happening? Your assumptions are correct I did not have any problems before the modifications. You know this last time I was at the Long Beach swamp meet I was talking to Jim Brock about my Porpoising and maybe getting some trim tabs. After talking to him I found out I was using the place diverter wrong. For example when I would get in to big chop I would raise PD and that would create the Porpoising so now I lower the PD when IÂ’m in some choppy water but now I get bow-steer. WTF IÂ’m confused!
I wasn't in your boat, but I had one very similar many moons ago. Even with a straight thrust line (no diverter, no droop) it had a very slight tendency to hunt in choppy water. If you hadn't driven a jet before you would probaby dismiss it as normal, but it isn't.
As OldBuck said, you need to moderate the use of the diverter. Since your hull is more prone to bowsteer, you should really make sure you are adjusting your diverter (cable or Hyd.) so that you cheat yourself out of the last couple of degrees down angle. If you're running a hydraulic unit, this will keep you from grabbing too much down nozle and should help somewhat with the problem. But the other thing you want to mess with is driving the boat without the droop. I have a feeling that could make the boat liveable without tending to the hook issue. You can play with the hardware you have to increase or lessen the effects of hook, but it is always there. If you're going out to a lake or river this weekend, set the boat up without the droop before you leave and give it a try. It can't be any worse than it currently is. Take the droop, all your droop related hardware etc. with you and if you have time/feel like messing with it, start trying different combinations.
Good luck and let us know how it goes.
Chris

[CandyA$$]

nothings normal if you have to ask.

[mevale]

I took the boat to Havasu for the 4th of July. But before that I talked to Bruce (Squeezing Spectra) and he suggested changing my loader before I do any thing. I talked to Jack about what was happening and told him about Bruce suggestion and every ones suggestion as well. He thought changing the loader would be worth the try. He gave me a more aggressive loader for me to try. WOW it worked!! The boat steers straight and I can correct all the porpoising with the place diverter. Thanks to all that posted to help me out!!
Thanks
Joe

[flat broke]

Good to hear that you got it straightened out. Props to SS for that suggestion. Since you are obviously grabbing a LOT more water now, did you notice a change in WOT RPM or WOT speed?
Chris

[mevale]

Good to hear that you got it straightened out. Props to SS for that suggestion. Since you are obviously grabbing a LOT more water now, did you notice a change in WOT RPM or WOT speed?
Chris
You know I was so happy it was going straight. I really did not look at any thing else. Next time out I will. Thanks for all the help and for helping me covey the problem I was having.
Thanks
Joe