handling issue

[bbar]

Hi, Took first ride on my first jet boat and have a couple questions about how it handles.

2 things surprised me: 1- at moderate speed, when I turned the wheel to put it in a turn, it did not respond for 2-3 seconds.
2- when it did respond and was making the turn (lets say left) it was skidding (which I am used to from my jet ski), but then it suddenly would bite ( or plant, or stick) almost sending me overboard off the right side of the boat (towards the outside of the turn)

Are these normal for jet boats? If so, how do I modify the boat or change my driving habits to eliminate these problems.

***my boat is a nautica rib jet 10 (10ft. rigid hull inflatable)**** Thank you.

 

[seadude]

Congrats on getting that POS running! (maybe this is why they went out of business )
Just a thought - if you could fit one of the aftermarket rudder systems on your outdrive (jetski model?) that might help.

 

[bronze_10]

Add throttle as you start importing the turn.. then ease it back down before you are thrown out and skip across the water like a rock!

 

[bbar]

Follow up. After another run, I think I know why I have some of the problems, but don't know what to do about it. When the boat gets on plane and "comes down", it is coming down too far and begins to plow, which turns the whole steering/handling deal into a mess. The wake from the pump looks very "high " as in close to the top of the water. The pump on this was missing when I got it. We got a correct pump from a '97 yamaha 760 wave venture; but I'm wondering if the pump nozzle on this pump is an up angle (5 degree?) which would force the nose down, when maybe I need a 0 degree straight nozzle. Any thoughts are appreciated.

 

[tdonoughue]

I think you have that reversed, no? A 5 deg up angle on the jet would force the bow up. At any rate...

First thought would be whether you could shim the jet. Might cause leakage, which might be problematic, but it might get you a few degrees.

But I do agree--what you describe in turning and in stopping could be that your jet is pushing the bow too far out of the water. In turns, that would mean that until you slow a bit to catch more of the keel, you would be skidding. Stopping frequently causes wonkiness in my boat, too. If you let off the throttle too quickly, the lack of thrust will give you lack of direction (basically) until the boat settles off plane. For me, I try to back down more slowly, which helps a lot.

 

[bbar]

My bow is being pushed too far into (not out of) the water at speed, so it is making the boat unresponsive. It is plowing. I am used to putting weight into the front of boats to get the nose down, but I can't get any weight out of the front of this. The fuel tank (11 gallon but only half full now) is right in the nose, and the motor is pretty far forward. If my nozzle is an up angle (which I think it is) that is only making things worse, which is why I'm trying to find out if my nozzle is an up angle or not. Thanks.

 

[tdonoughue]

Trimming up (e.g. angling up the thrust direction, jet or prop) lifts the bow, no? And trimming down too much causes plowing.

When you are turning, do you lose just the back end of the boat, or the whole thing until it bites? I would think with plowing that you would have immediate bite (though you might lose the back end). Either way, do you have enough of a lip where the jet meets the transom to be able to shim?

 

[Gym]

@bbar I do have to agree with @tdonoughue in that if your jet pump is 5 degrees up that will force your stern down forcing your bow up. Whereas you have indicated your jets are kicking up a higher than normal wake I agree with your 5 degree up statement but that doesn't agree with the nose plowing statement. I'm suggesting one of two possibilities. Either the rib is not inflated to a high enough psi or your center of gravity (CG) is not correct. Are you sitting too far forward? Is your fuel tank too far forward? Are you alone or with company when this happens? Maybe some pics would help.

 

[bbar]

Hi, T don is correct. I was wrong in my original statement. Up angle will make the bow come up. I have determined that I have a straight angle nozzle. So my question now becomes: Does anyone make an up angle nozzle that will fit on a '97 yamaha 760 wave venture pump? This boat has the fuel tank right up in the nose and the engine sits pretty far forward. It is a bench seat at the steering wheel so no ability to change seating position. Thanks.

 

[tdonoughue]

This might help: https://jetboaters.net/threads/adjustable-trim-and-directional-reverse-bucket-install.17569/

 

[bbar]

thanks, tdon. I don't have any room under there to attempt anything like that.

Assuming I can't do anything to the pump to compensate, does anyone know if there is something I can do to the underside of the hull that will make the bow stay up?

 

[tdonoughue]

Hmmmm... That is a tough one. I know of lots of things to push the bow down, but I can't think of anything to push it up absent messing with the pump. Or something that would fundamentally redesign the hull (which I assume is out of the picture). You might be able to round out/smooth the back of the hull with a 45 deg piece added (so the back looks less like this: L and more like this: \_) That may create enough low pressure on the back to bring the aft down the the bow up. However, as that 90 degree angle is what causes the boat to be a planing boat, I would expect that you would have more trouble getting on plane.

 

[Julian]

Photos would help a lot!