SX/SXi/SXi Pro foam

AlexanderD

rz350 racer
Location
whitby ontario
hey guys,

just wondering if the sxi pro has the same issue with water logged tray foam as the SJ's do. mine seems overly heavy and i was thinking this might be the reason.

thanks in advance
 
The foam does not hold water like the superjet but the hull can, drill the back of your hull and put fittings in it so you can drain if it gets water in it.
 

AlexanderD

rz350 racer
Location
whitby ontario
hummmm> conflicting information.
i was about to believe the no holding water bit because the foam in the front of the ski and in the hood is closed cell Styrofoam which cannot hold water.
what kind is in the back?
 
How does the foam not hold water I just de-foamed mine and could pick up chunks and ring tons of water out. I dropped about 25lbs off just de-foaming

I said it does not hold water LIKE a Superjet, it is closed cell foam but it can still hold a some water nothing like the yamahas. 25lbs. of water in your foam? That means your sides of your hull with foam in it can hold 3 1/2 gal. of water Hmmmm!
 

AlexanderD

rz350 racer
Location
whitby ontario
i have seen other threads but they all seem to be on the sx not the sxi. i hope someone has a definitive answer...? pics/or first had experience would be great!
cheers,
AlexanderD
 
what kind of foam is in the back of the 99 sxi 750 pro hull?

My 98 pro had CLOSED CELL foam. I have done footholds and removed foam on a 2000 pro and it was closed cell too. SX hulls might have something different.
 

Attachments

  • ski 015.jpg
    ski 015.jpg
    80.9 KB · Views: 57
Last edited:

AlexanderD

rz350 racer
Location
whitby ontario
this thread seems to contradict. that looks just like the foam that is found in SJ's. the stuff that will hold water. yours didn't look like this?
the only way i guess i will know for sure will be to cut the thing up. i'll have to anyhow for footholds.
thanks for the help guys!
 
I am not 100% sure about the pro, but I do know that the sxi is a 2 part foam that is supposed to be closed cell, but does retain water. Its the same foam they blow into all boats. It will eventually retain water if there are any leaks. The only true closed cell is polystyrene which is the white foam in your nose and hood. I have also heard they use polystyrene in the sxr tray which is the way it should be done. I just did footholds on a superjet that had a cracked tail and leaky exhaust and it had a little water around the damaged area but not bad. My sxi on the otherhand was horriable due to leaky footholds and a cracked bottom. I really did take out 25lbs+ of weight because we weighed it before and after. I had 4 five gallon garbage cans of wet foam. Pretty much every ski is going to eventually have some water saturation because of the two part foam used. It just breaks down over time like anything, SXI or superjet! I am going foam free for now, and putting drains in the back of my ski, plus duel 1100 bilges.
 
I'm with you on taking the foam out for weight, on the 750 you can take the foam out and the fire estinguisher tube and save a lot of weight. I just leave foam in on the bottom hull section and seal the firewall up really good and it works great.
 
I said it does not hold water LIKE a Superjet, it is closed cell foam but it can still hold a some water nothing like the yamahas. 25lbs. of water in your foam? That means your sides of your hull with foam in it can hold 3 1/2 gal. of water Hmmmm!


So tell me how a yamaha holds more water in the foam when its the exact same 2 part foam they blow into every boat and pwc? So what your saying is yamaha uses a cheaper home depot foam out of a can? If so I am glad I am a kawi rider! (joking) When I defoamed I weighed before and after and I took out 25+ pounds consertivly, probably more though. Think of how much volume is in the tail of a ski and if you have a extreme saturation as I did how much that is going to weigh! With out foam you could probably get 15 to 20 gallons of water in the tail. Think about it! HMMMMM!
 
So tell me how a yamaha holds more water in the foam when its the exact same 2 part foam they blow into every boat and pwc? So what your saying is yamaha uses a cheaper home depot foam out of a can? If so I am glad I am a kawi rider! (joking) When I defoamed I weighed before and after and I took out 25+ pounds consertivly, probably more though. Think of how much volume is in the tail of a ski and if you have a extreme saturation as I did how much that is going to weigh! With out foam you could probably get 15 to 20 gallons of water in the tail. Think about it! HMMMMM!

The yamaha is diffently different foam, I like how everbody wants a superjet because they are so light, but everybody has to defoam and reinforce the hull so they don't get water log or break. lol Did you take all of your foam out on your ski and hood and handlepole and do you know how much it weigh dry when you was done?
 
The yamaha is diffently different foam, I like how everbody wants a superjet because they are so light, but everybody has to defoam and reinforce the hull so they don't get water log or break. lol Did you take all of your foam out on your ski and hood and handlepole and do you know how much it weigh dry when you was done?


I would still like to know exactly how its different. I have been inside both skis and it looks and feels the same? I don't think its just superjets that a issue with water intrusion into the foam, I think its just that they are more likely used as a freeride ski. I do have a friend thats just runs bouy's and his is water logged though. My hull was right at 100lbs with pump and driveshaft minus hood and everything else. The hood weighs a ton, like 25lbs and thats the next thing to go on a diet! I am not sure yet if I am leaving my nose foam out or not, it looks cleaner with out it. It weighs near nothing. And for my pole I run a bad attitude stainless that is lighter than stock, not sure exactly how much, but it stands up with a stock woreout spring. I will weigh it all here in a week or so when I am done. Not going to be the lightest ski but way better than stock. Leaving the foam out is a experiment for me to see how the hull reacts to it. It may break in two or sink, but maybe it will be great! Who knows. I like the idea of haveing the extra flotation in the rear should I take on a lot of water and dry foam weighs near nothing a couple of pounds maybe. I just think its easier to try it without and add it later should I need to than have a issue with water saturation a year down the road.
 
I would still like to know exactly how its different. I have been inside both skis and it looks and feels the same? I don't think its just superjets that a issue with water intrusion into the foam, I think its just that they are more likely used as a freeride ski. I do have a friend thats just runs bouy's and his is water logged though. My hull was right at 100lbs with pump and driveshaft minus hood and everything else. The hood weighs a ton, like 25lbs and thats the next thing to go on a diet! I am not sure yet if I am leaving my nose foam out or not, it looks cleaner with out it. It weighs near nothing. And for my pole I run a bad attitude stainless that is lighter than stock, not sure exactly how much, but it stands up with a stock woreout spring. I will weigh it all here in a week or so when I am done. Not going to be the lightest ski but way better than stock. Leaving the foam out is a experiment for me to see how the hull reacts to it. It may break in two or sink, but maybe it will be great! Who knows. I like the idea of haveing the extra flotation in the rear should I take on a lot of water and dry foam weighs near nothing a couple of pounds maybe. I just think its easier to try it without and add it later should I need to than have a issue with water saturation a year down the road.

It must be the difference in the pro hull since it is a hand laid glass bottom, I have had my sxr and my pro apart and they had the same foam and I have seen a SJ RN and the foam is a different texture. How did you get your hull down to 100lbs with the pump and driveshaft in it?
 
It must be the difference in the pro hull since it is a hand laid glass bottom, I have had my sxr and my pro apart and they had the same foam and I have seen a SJ RN and the foam is a different texture. How did you get your hull down to 100lbs with the pump and driveshaft in it?

To tell you the truth, I really do not know how it was so light other than it was gutted. I also forgot to add that was minus tray and footholds, but they do not weigh that much 8-10lbs tops. My hull is SMC and is superthin. Its about half as thick as the superjet and sxr. And that was without the hood I think most hull weights are with the hood included. I need to weigh it again!
 
To tell you the truth, I really do not know how it was so light other than it was gutted. I also forgot to add that was minus tray and footholds, but they do not weigh that much 8-10lbs tops. My hull is SMC and is superthin. Its about half as thick as the superjet and sxr. And that was without the hood I think most hull weights are with the hood included. I need to weigh it again!

I just went to your build thread and saw your foam and it is diffently not the same stuff, my foam is just like what is under your fuel tank and what in the hood. No wonder you was question about the foam that is the nastest stuff I have seen! They must have change it to the other when they went to the pro hull in 98. Your build is looking good and I love the silver paint.
 
I just went to your build thread and saw your foam and it is diffently not the same stuff, my foam is just like what is under your fuel tank and what in the hood. No wonder you was question about the foam that is the nastest stuff I have seen! They must have change it to the other when they went to the pro hull in 98. Your build is looking good and I love the silver paint.


Thats awsome that they have styrofoam in the tray. I would have never known being that they are pretty much the same ski. I knew they put styrofoam in the SXR. When you said closed cell you had me confused, because they call the garbage in the sxi's and superjets closed cell too, which its not! I wanted to put styrofoam in my tray but didn't want to remove all my tubes to do it in one piece. Thanks for the compliment on the paint I worked hard on it!
 
Location
dfw
All foam is not the same. Yamaha clearly uses the wrong formula. By all accounts including my own, Kawasakis foam does not soak up water. I have tested several types of 2-3lb foam that would gain less than 1% after being submerged in 12" of water for 7 days. Im looking for an inexpensive commercial version of these foams. Until then I just seal the hull until it holds vacuum.
 

Cannibal

Tasty Human
Location
Summit Lake, WA
I removed 30lbs of soaked foam from my 95 X2. I replaced it with about 5lbs of pink polystyrene from Home Depot along with drains in the back.

The back of the ski floated just under water. The only thing keeping this ski floating was the air in the engine compartment.

Unless the 95 SXi's and my 95 X2 were made in different places, I'd venture to say it was the same 2 part foam.
 
Top Bottom