Do you think a freestyle trim kit contributes to porpoising?

[segmentlime]

My 1996 SJ701 came to me with a trim kit. Based on comparing the ride with the trim kit enabled versus when the trim is set fixed / static, I believe at least my ski wants to porpoise more with a trim kit. Mine does not have a return spring and I have never tried a return spring but I doubt this would mitigate much if at all.

Thinking about the forces involved, it kind of makes sense that a trim kit would allow ski to porpoise more easily.

What do others think?

 

[Big Kahuna]

If you have any positive trim dialed in then yes. The flow angled upwards is going to make the nose "Bounce" as you run up the lake. Reduce the amount of positive trim.

 

[segmentlime]

If you have any positive trim dialed in then yes. The flow angled upwards is going to make the nose "Bounce" as you run up the lake. Reduce the amount of positive trim.

I am talking about manual positive trim systems where pulling the handlebar lever pulls the nozzle upwards to add positive trim for tricks, jumps, etc.

When the lever is not being pulled then the trim nozzle is loose or floating, and I figure since it is not held statically then it can moves up a bit and contributing to any porpoise type action the ski might be wanting to do given acceleration, rider weighting etc. As you point out a static slightly negative trim helps to press the nose down and serves to de-amplify any porpoise cycles, but when the nozzle is floating as it is with a trim system then there are no such forces coming from the nozzle.

I see that some systems have a return spring that pulls the nozzle back down when the lever is released. Having never used one with such a spring I don’t know if it would make much of a difference or mitigation, but it seems like it wouldn’t. This was part of my question.

 

[Big Kahuna]

Thrust keeps it straight.

 

[kevbo]

I once disconnected the gimbal cable and ran with the steer nozzle hanging limp. It centered and made no difference in trim once the engine was running.

 

[bird]

Porpoising comes from a bad rider. Just like death wobbles on a skateboard. Change your stance and ride it out.

The only skis that don't porpoise stock are 2008+ SJs and 2003+ SXRs. It took OEMs 30 years(1973 JS400) to figure that out lol.

 

[Myself]

Change your stance and ride it out.

Yep......When I first started riding my 650sx I had trouble controlling it. I'm 6'8" and currently 230#. I can lean off the rear and ride full throttle on it now. Just have to get a real good feel for the hull so you know where it's happy with you on it.

 

[TheBuzzard]

Trim is useless on a stock hull unless you ride surf and pull trim to keep it from nose diving Pearling. It probably has a short rideplate on it and that's why it porpoises. I had a drop nozzle on one of mine and when I pulled the drop it stopped porpoises. I put a worx dominator plate on it and it rode nose down like the drop was pulled and pulling the lever no longer did anything. If you ride 6ft or larger surf that breaks, you don't need a flip nozzle