cavitation vs. porpusing

whitca

whitca

Location
Tri-Cities, WA
Porpoising is when the nose of the ski bounces of the water when your at a steady speed making it difficult to ride. Cavitation is when you get air in the pump and the prop spins without any water creating thrust...also making it difficult to ride.

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Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Porpoising is a vertical oscillation of the ski as you ride. Like it's constantly bunny-hopping.
It's mostly caused by the rider and can be cured by the rider.

Cavitation is the introduction of gas in the jet pump. This can be caused by a wrong impeller pitch, a worn or damaged impeller or pump, a faulty drive shaft seal, a bad intake grate seal, a bad pump shoe, a bad ride plate.
It feels like a slipping clutch. The rpm's are climbing, but the ski is not moving accordingly.
 
ger87410

ger87410

How did I get here?
Location
Fort Worth
It can't really be more obvious.

Is your ski's nose bobbing up and down at speed and you don't want it to, you got porpoising.
 
ger87410

ger87410

How did I get here?
Location
Fort Worth
Aren't you the one in the other thread about a longer ride plate, or am I confusing you with someone else who has the EXACT same problem?

Anyways, his conclusion was that sponsons are the way to go to reduce porpoising without adversely effecting speed too much. The intake grate alone can eliminate porpoising, but will adversely effect speed.
 
smoofers

smoofers

Rockin' the SQUARE!!!!
Site Supporter
Location
Granbury, TX
OR instead of throwing money at a problem that is RIDER based, learn how to ride the ski. Spend more time on the ski, put more weight forward in the tray, and play with your weight distribution to solve the problem.

BAM!

People spending money on stupid parts to "solve" a problem that is the rider's fault is just stupid.....
 
smoofers

smoofers

Rockin' the SQUARE!!!!
Site Supporter
Location
Granbury, TX
750sxi said:
i asked for it so bring it on and yea thanks bam, is your ride all stock?
Click to expand...

I don't ride a 750, but I ride a stock 650 Superjet (handling wise). Anybody new to standups is going to have the porpoising problem - you have to learn to ride the ski to solve it. If you buy sponsons and a rideplate and god knows what else, you will be pissed as hell when you jump back on your ski and it sill porpoises. Put your weight farther forward (like as far as possible) in the tray and experiment while you ride. You WILL learn to overcome the porpoise, just takes time and PRACTICE.


Good luck dude.
 
SQUARE JOEL!!!

SQUARE JOEL!!!

Location
Look for me when you see me coming!
smoofers said:
OR instead of throwing money at a problem that is RIDER based, learn how to ride the ski. Spend more time on the ski, put more weight forward in the tray, and play with your weight distribution to solve the problem.

BAM!

People spending money on stupid parts to "solve" a problem that is the rider's fault is just stupid.....
Click to expand...

But that takes all the fun out of it!!!

Funny how we JUST had this exact same conversation the other night!

To the OP, if you're hell bent on mods...or just interested in blowing coin (you could just pass it my way) a grate MAY help REDUCE porpoising but may also change how your ski handles which may require learning to ride the new grate. Some grates can take a small amount of top speed off but hardly noticeable. An extended ride plate can also help reduce porpoising but there is no one fit all solution.

Like my knee greaux smoof said, it all goes back to rider position in the tray. Try different things and see what works for you, no mod can replace time in the tray. How big a boy are you anyway?
 
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