Ride plates for Jet skis are like oil for 2-strokes - everyone has an opinion and most of them are wrong.
This explanation is about JS style hulls - but - the facts part is true to most any personal watercraft. So keep that in mind - this is ABOUT the JS hull.

FACT - if you want to ride / race closed course competition then you will NEED a ride plate that is suited to rough water riding. Simple as that. What makes it "suited" is loading the pump. The more time the pump is in the water - pumping water - the faster you will go. The longer the plate is - (extended beyond the back of the hull) - the further away it will push the pump intake. This is called - going backwards. The deeper the plate is (distance away from the pump) the further it pushes the hull out of the water and therefore pushes the pump intake out of the water. This is also referred to as going backwards. What you want and need to aid you in your quest for speed in closed course racing is a ride plate that extends NO further or even less than the end of the hull and a ride plate that will get as close to the pump as possible. Doing this will allow the ski to sink into the water the furthest it can and still perform and allow the pump intake to be as near to the back of the ski as possible. A JS hull at 40 MPH has only the very back of the hull still in the water - with the outer parts of the hull just touching form time to time as a balance skeg. SO - this is more important than most think. To get the best plate for this application - you will most likely have to make one yourself. Cut and weld - grind and smooth - fun ! A "ripper racing" ride plate of an old Jetco cut and weld is close and a good start point or you can cut and weld a stock one. You will need to grind / mill a clearance groove into the plate to clear the pump - grinding clear through right in the area where the pump nozzle attaches to the pump for clearance is OK - but - best if you don't. Then you will need a straight edge to make sure the plate is flat and follows the same plane as the rest of the hull - you simply must NOT have the front of the ride plate hanging deeper into the water than the back - following the same plane as the rest of the hull. To adjust - mill / grind material from the area where the ride plate bolts to the hull. There is about a half inch of metal there to play with. SO - to recap. Make your own plate ( or buy a cut and weld - Robert Sand likely has some ) - then carefully "set" it so it is the same plane as the front part of the hull ( just ahead of the pump intake ) and as close to the pump as you can possibly get it. Extending the plate is an absolute no no. Cutting it back to shorten it "can" be done - but - it should make little to no difference as the rest of the hull will just compensate. So - leaving it the same length as the rest of the hull is best for speed.

The above is simply physics and fact. Arguing what is written above is your privilege - but - that does not make your argument valid. Sorry.

FEELINGS NOW - the "other" 99% of jet ski riders - those who just want to have fun - should and do ignore the above. Even some racers ignore the above simply because they went out and "tested" a given ride plate and liked it the "best" - and - when you ask them where they tested it - they will tell you - the lake or the river and the conditions were SOOO great and the water was like glass. And - when you tell them they just wasted their time - they think YOUR the idiot. BUT - let us assume that you are one of the other 99% who just want to have fun. First - the stock ride plate - is OK - just OK for "most" people - whatever that means. If you are having trouble with the ski porposeing ( front end bouncing about ) - try riding further forward. If you are on the heavy side - you might try an extended ride plate - many ( most ) bigger guys like them. Just keep it reasonable. As for skegs and fins - don't go there. That surface is THE most important surface on the bottom of your hull - your ski is literally riding on that plate. Skegs and fins are brakes and slow you down and make corners harder to carve as they do not change direction with the turn. If you are more than 180 pounds or less than 120 pounds your gonna need to spend some time trying different plates. Just make sure that whatever you try is "true" to the bottom of the hull. MOST aftermarket ride plates I have checked do NOT follow the hull plane - some are more than a half inch off - and that is simply unacceptable in any case. Also - some plates are just flat heavy and pull the hull inserts out - stay away from them - there is no need for the plate to be a 20 pound accessory.
Finally - a word about "directional stability" - or - complaints about the ski being squirrely. This is almost never your ride plate. The intake grate is the last line in directional stability If it is out of line - as in not true to the front or rear part of the ski - it will cause the ski to pull to one side or tip. ( severe "tipping" however is usually a loose hull end cap ) - if the grate arms are bent it will cause really bad handling - no arms at all will create a "greased monkey" kind of handling - try it sometime :) :) - you will be shocked. SO - the intake grate is where you look for directional stability not the ride plate. I have seen MANY folks try 5 different ride plates to get the handling they want - and finally install a good intake grate that solved all their porposeing and handling problems. Never overlook the intake grate.

SILICONE - NEVER - EVER - silicone the area between the pump housing and the ride plate and intake grate where they all come together ( right near the single bolt that attaches the intake grate ) - silicone the pump into the pump intake tunnel - and - the ride plate bolt on area if you must - but STOP there. Just trust me on this one :)

Most people who learn to ride with a proper intake grate ( Jet Enterprises ) and ride plate as described in the beginning ( cut and welded for max in the water pump work ) - never go back to an aftermarket plate.  :)

By Cliff Jones