How to stop porposing

[jbone]

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I have a 21 ft Shockwave with a 502.
The jet is set back with a droop and a ride plate.
I have only taken it out twice and want to eliminate the minor porposing at mid throttle. I am currently having to trim the bow way down to eliminate it which is not the most efficient way to go. This is my first jet, so I'm not sure exactly what to do. It rides great at wot.
I think the ride plate needs to be lowered at the rear. Is this correct and if so, how much should I shim it down to start?
J

[BrendellaJet]

Just drive faster!
Where is the plate set now? Best way to fix it is to play with it a little bit at a time.

[Hallett19]

Talk to froggy or squirtcha or HB jet, they have a good idea of what to do in those situations..... Do you have a place diverter ?

[PLACECRAFT20]

I have a 20' placecraft daycruiser that had the problem at wide open throttle. I could never ajust it out. I talked to Tom Peterson at Rex Marine who set me up with a adjustable trim tab setup. It is all out of stainless and looks great. It cured my problem. I have a great picture but the image center is messed up so i cannot post it.

[ryantparks]

I have the same exact set up on my Ultra but I have a place diverter but not a droop and with the diverter I can plane it just right to eliminate any porposing. 21' w/502

[Nucking futs]

I would much rather have a slight porpose at mid throttle than a mean porpose at WOT.You can trim the boat out with the P/D and just find the sweet spot at cruising speeds.You could play with your plate a bit and see if that helps but it really wont see anything at mid range with that heavy of a boat.I also have tabs on my 20' cruiser but i use them mostly in the big chop at WOT.If it feels like its dragging ass then lay into the throttole and get the boat out of the water more.I run my ride plate at 4* up and she airs out good for the H.P. i have, which is not much!!
Tim

[1Bahnerjet]

How to stop porposing ?
Outlaw WakeBoard Boats :yuk:

[jbone]

Thanks for the replies. I'll get with Barry at Shockwave to find out where it is set now and go from there.
J

[RCB19]

Sounds like you might have some problems with the bottom of the boat. I'd take a close look at that first.

[Nucking futs]

Sounds like you might have some problems with the bottom of the boat. I'd take a close look at that first.
I don't think there is anything wrong with the bottom,Its just a heavy boat and the hardware is set up for WOT.Alot of boats will have this problem at cruising speeds,
Tim

[jbone]

Your right about it being heavy. Their web site lists it at 3400 lbs. Shockwave doen't normally set back their jets, but from talking to other jetters, It was something I wanted them to do. As far as the bottom, it was blueprinted at Shockwave. Some things I left out that may be important.
It is a full set back with a shoe and a ride plate. It has a droop and a diverter. I can use the diverter to stop the porposing, but I feel like the bow is farther down than it should be.
It does ride great at wot, but would like to get a smooth ride at cruising speed without having to push the bow down so much.
I was hoping it would be a simple fix, like a shim to change the ride plate angle.
J

[REGISTERED USER]

If you're carrying any weight in the bow area, you might want to try taking it out or moving it around first.

[Bense468]

A lot of cruisers have this problem. I have the same problem with my ultra 20. I am going to be playing with it here real soon. I will keep you updated on what works. Hitting up glamis this weekend, then its time to start playing with ride plate, shoe (trying a backcut) loader etc. 1 small step at a time. I have tabs as well.

[olbiezer]

have the same problem with my biezer jet. greg at gs marine says it rocker in the bottom and not to use a droop on it cause it changes the thrust line. also to just use the down angle on the diverter till u get past that rpm area.