Thread: Gp Ride Plate Angle
01-08-2007, 01:31 PM #1
Gp Ride Plate Angle
Has anybody shimmed their ride plate down in the front on a GP hull? I have the Group K mod on my R&D with no shims. I am curious if anybody has shimmed down the front on any plate? I know the rideplate angle is important on the GPR and this is where the GPR guys have found alot of speed. Since our hulls are shorter, we may not be able to get away with much shimming in the front without causing an uncontrollable porpoise. I know that there is a sweet spot on our hulls. When I do topspeed runs on my ski, if it starts to get a slight bobble I can move futher back and it will line out, or sometimes it will line out if I move my weight forward. My ski never bounces to the point of unhooking, but sometimes it will bobble ever so slightly. I know most people have shimmed the back of the plate down on our hulls to eliminate any bounce, but I think if you have trim tabs, you could experiment with shimming the front down. Also note that I can do full superman with low fuel, and a 5 degree nozzle and the Group K R&D ride plate mod. It seems my hull may be at the sweet spot, and I would probably get some porpoising from shimming the front of the plate down, but some of you guys may want to experiment with it.
01-08-2007, 01:38 PM #2
If you look at my hull in these pics, you can see there is hardly any spray until the very back of the hull.
01-08-2007, 02:10 PM #3
Mine is shimed in front.
My 99 was shimed in the rear I did not like it.
I am running some fairly thick washers in the front on a group K plate.
Speed runs are done with trim all the way up.1/2 tank or less.
01-08-2007, 02:14 PM #4
Scotsman, thats good to know some people have tried it and liked it. That may be the last mod I do before MBIII. I have a few other things I am going to do first. Do you know how thick the washers are?
01-08-2007, 03:09 PM #5
Does Group K still mod the R&D plates? What do they charge?
01-08-2007, 03:20 PM #6
Yes, they charge $58.00 according to their website.
01-08-2007, 03:35 PM #7
My guess on thickness would be 2-3mm or .100-.150".
I see a slight buck at somewhere between 35-40mph a speed I never ride at but no buck if you go straight to full speed.
I always keep the trim 1 up or 2 up norrmally 2 up.
I found shiming the ride plate in the front mandatory on my piped boat when I had it.
You can also adjust your steering nozzle so it gives more lift by offseting a deg or two upwards.
You need to set your trim to neutrall and measure the distance top and bottom between the end of the exit nozzle and the end of the steering nozzle.
This should be the same.
Make a run (I use trim all the way up) and take speed rpm etc.
By adjusting it so the top measurement is smaller than the bottom measurement you get more lift up to the point of creating more drag in the nozzle from deflection.
Adjust up a little and make another run take speed etc.
Repeat this proccess a little at a time watching for speed to drop off.
Watch speed and rpm for the sweet spot.
You should be able to squeeze a little more lift and speed out of your ski this way.
01-08-2007, 05:46 PM #8
Is there only one type of R&D plate that works best?
01-08-2007, 06:12 PM #9
Group k cut plate is best I have tried.
You can dress up the R&D by polishing it and flatening the bottom surface.
01-08-2007, 06:43 PM #10
What's the part umber of the R&D plate that Group K does the mod to?
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