Super Jet Foam 101- if you plan on refoaming your superjet soon, read this first

[Scribbleheli]

Question for you go getters out there.

Has anyone found a way to get the EPP/BPP in ping pong size/shape?

Seems like a lot of people are for the properties of the BPP/EPP stuff. And of beer pong balls

Would foam balls like half the size of a beer pong ball be a good compromise?

 

[BrightE's]

Question for you go getters out there.

Has anyone found a way to get the EPP/BPP in ping pong size/shape?

Seems like a lot of people are for the properties of the BPP/EPP stuff. And of beer pong balls

Would foam balls like half the size of a beer pong ball be a good compromise?

You'd have to either mold them that way, or waste a ton of time, material, and effort cutting a thousand spheres. Probably not a very promising route to take either way since it doesn't sound like they're commercially available molded in that shape.

Just curious, if you are wanting to take the ball fill method, why not just use the PE ping pong balls? Do you need them to be foam for any reason?

 

[Scribbleheli]

From reading this thread. Sounds like normal ping pong balls are a bad choice. But beer pong is made from different material. (but I cant narrow down what exactly is different)

It was more a question for those guys who had the idea to make a big mold for the back end of the tray. But it was argued that it would be unreasonable because everyone's application would be different. By the time the custom cuts are made by the end user. It wouldn't be cost effective.
I thought if that supplier could make pong ball sized foam spheres. It would be a happy medium of easy to install EPP. Vs getting huge sheets of the stuff and cutting and layering into the tray like most people are doing that want to BPP/EPP benefits.

 

[Vumad]

You're over thinking it and not thinking about it enough. Every hull is different. This would have been a good plan for Yamaha from the factory, but not for modified hulls. The foothold, the exhaust routing, the cooling lines, drive shaft. It can't all be one piece because it has to fit under the drive shaft, around the exhaust. By the time you are done, you would have so many parts of the kit it wouldn't be cost effective, or if you did it as one big piece, by the time people were done removing everything inside of their ski to fit this stuff in, it would have been quicker (and much cheaper) to just buy a sheet of the stuff and cut it to fit.

You might have some success having a ping pong ball EPP kit made so people can use foam instead of ping pong balls, or some other similar method, but a mold of the hull would be too specific to sell.

From reading this thread. Sounds like normal ping pong balls are a bad choice. But beer pong is made from different material. (but I cant narrow down what exactly is different)

It was more a question for those guys who had the idea to make a big mold for the back end of the tray. But it was argued that it would be unreasonable because everyone's application would be different. By the time the custom cuts are made by the end user. It wouldn't be cost effective.
I thought if that supplier could make pong ball sized foam spheres. It would be a happy medium of easy to install EPP. Vs getting huge sheets of the stuff and cutting and layering into the tray like most people are doing that want to BPP/EPP benefits.

Both of those came from the same post. No one is presently making such a thing. There are lots of foam balls available, mostly at craft stores. Everything I have seen is polystyrene. I haven't found, and no one has claimed to have found to my knowledge, anything comparable to a ping pong ball made of polypropaline. Yes, it would likely work well, possibly better than beer pong balls, but it is currently unavailable.

 

[jeremy chambon]

a custom molded block of foam is the way to go for sure. bpp/epp cuts so nice with a hot wire. any one can make a hot wire with 15 mins on there hand. i be leave a lot of riders would put that in there ski just because it will just about be a drop in fit. if you ever decide to go back and open up your tray for some kind of work you did not have planed the block will lift right out. the research has been done about the foams capability it should work out great very interested in see what the foam suppier says

 

[txsuperjetfreak96]

dam wish I saw this earlier almost tempthing pulling the polystyrene I got in there out,

 

[waxhead]

Has any one figured out how to get the old stuff out nicely. Is there something you can pour in there that actually dissolves the original foam

 

[Vumad]

Has any one figured out how to get the old stuff out nicely. Is there something you can pour in there that actually dissolves the original foam

If you open up the entire back, a pressure washer will get it all out clean. Cut the big parts out with a saw, a hand tree saw works good, and a prying tool. Then you can pressure wash the rest out. Makes a crazy mess but gets it spotless. Don't do this unless you cut out the entire tray.

 

[dpenta13]

does anyone have a pic with there tray cut out

maybe some pics with an without foam, i just want to see what im getting into
this is my first SJ

 

[Christian_83]

http://www.pwcforums.co.uk/rn-superjet-freeride-surf-project_topic36078.html

Its like opening several cans of worms!

 

[txsuperjetfreak96]

after putting polystyrene foam in

 

[SJ 701X]

I remember reading about how some racing teams form contoured seats by placing foam beads into a sealed bag, mixing with some adhesive (epoxy?), pulling all the air out and then having the driver jump in with the bag placed behind them. I wonder if there would be a way of mixing foam beads with an adhesive (epoxy?) in a bag and then dumping them into the hull? Might be kind of tricky and not sure how much weight the adhesive would add?

Alright I have an idea. Mix the beads with the epoxy and pour them into the tray. They stick very nicely, I watched the episode on how it's made yesterday. Then put a vacuum bag cover in the tray. Make an insert for the tray area and press it into the tray to form the tray area. Make cut outs for foot holds in the tray area insert so you can press your own foot holds into it. Vacuum all the air out and let it cure. Pull everything out and you have a perfect molded tray and all you have to do is layup some fiberglass. Would be an awesome kit for somebody to sell.

Sent from GS3 Synergy

 

[MikeyB]

Alright I have an idea. Mix the beads with the epoxy and pour them into the tray. They stick very nicely, I watched the episode on how it's made yesterday. Then put a vacuum bag cover in the tray. Make an insert for the tray area and press it into the tray to form the tray area. Make cut outs for foot holds in the tray area insert so you can press your own foot holds into it. Vacuum all the air out and let it cure. Pull everything out and you have a perfect molded tray and all you have to do is layup some fiberglass. Would be an awesome kit for somebody to sell.

Sent from GS3 Synergy

I had did some reading a while back on the kits that a lot of racers are using to make their custom seats. They listed the favorable ratio for foam vs epoxy in the info that I saved. Ill have to dig it up, Ive really been thinking about experimenting with this to see how it would go.

edit - I believe this is the information that I found previously:

http://www.apexspeed.com/forums/showthread.php?t=28492
https://www.pegasusautoracing.com/productselection.asp?Product=4525
http://www.apexspeed.com/forums/showthread.php?t=9531

I would be curious to see the weight difference between 2 part polyurethane foam and the epp bead + epoxy mix. It seems as if a minimal amount of epoxy is needed, just enough to coat the beads, but pigment must be added and a clear bag used to be able to see when it has been fully mixed. This could be a great alternative. I think I will try it when I re-foam my tray, mix the beads and epoxy in a clear bag, pull the air out and stuff it in the tray. Once it dries peel off the bag and shape as needed, then probably use sheet foam to form the sides of the tray

 

[SJ 701X]

I had did some reading a while back on the kits that a lot of racers are using to make their custom seats. They listed the favorable ratio for foam vs epoxy in the info that I saved. Ill have to dig it up, Ive really been thinking about experimenting with this to see how it would go.

edit - I believe this is the information that I found previously:

http://www.apexspeed.com/forums/showthread.php?t=28492
https://www.pegasusautoracing.com/productselection.asp?Product=4525
http://www.apexspeed.com/forums/showthread.php?t=9531

I would be curious to see the weight difference between 2 part polyurethane foam and the epp bead + epoxy mix. It seems as if a minimal amount of epoxy is needed, just enough to coat the beads, but pigment must be added and a clear bag used to be able to see when it has been fully mixed. This could be a great alternative. I think I will try it when I re-foam my tray, mix the beads and epoxy in a clear bag, pull the air out and stuff it in the tray. Once it dries peel off the bag and shape as needed, then probably use sheet foam to form the sides of the tray

I was thinking of just having a plywood form that went into the tray and rather than having to shape the whole thing in just use the plywood form. You could also shape the footholds with the foam. I guarantee it would be lightweight and super strong. All you have to do is put a couple layers of 17oz on top of it and you would be golden.

 

[MikeyB]

I was thinking of just having a plywood form that went into the tray and rather than having to shape the whole thing in just use the plywood form. You could also shape the footholds with the foam. I guarantee it would be lightweight and super strong. All you have to do is put a couple layers of 17oz on top of it and you would be golden.

For me personally I just think it would be more beneficial to shape my tray sides from sheet foam. However, based on some more reading that I have done it seems that not many adhesives bond to epp very well, epoxy being one of them. I think the race car seat kits are using eps foam.

 

[SJ 701X]

For me personally I just think it would be more beneficial to shape my tray sides from sheet foam. However, based on some more reading that I have done it seems that not many adhesives bond to epp very well, epoxy being one of them. I think the race car seat kits are using eps foam.

I doesn't even need to bond to the foam itself. It is going to encase it, you will still have plenty of structural support either way. This fall I may do it. Considering how easy it would be to vacuum bag it compared to cutting and fitting it seems much easier.

Edit: Couldn't we use XPS? Once the resin absorbs into the beads and seals them they would be waterproof right?

 

[MikeyB]

I doesn't even need to bond to the foam itself. It is going to encase it, you will still have plenty of structural support either way. This fall I may do it. Considering how easy it would be to vaccuum bag it compared to cutting and fitting it seems much easier.

If someone can find a supplier for the epp beads I will give it a shot. I think CA glue might work to bond the sheets.

 

[DEVIN]

I just found this tread, i also on this project in my round-nose hull. i know foam has been problems with getting wet, also i know that hull have same cracks in random places along with leaks from bolts. so my plan was to put on drain plugs with the ping ball idea so it could drain, but because of price on ping pong balls i decide to go with wiffle balls, golf and baseball size. this way any water trapped under the tray can always reach the drain.

 

[SJ 701X]

Wiffle balls don't hold air so if she starts sinking and the tray starts letting water in you're effed.

 

[swapmeet]

I just found this tread, i also on this project in my round-nose hull. i know foam has been problems with getting wet, also i know that hull have same cracks in random places along with leaks from bolts. so my plan was to put on drain plugs with the ping ball idea so it could drain, but because of price on ping pong balls i decide to go with wiffle balls, golf and baseball size. this way any water trapped under the tray can always reach the drain.

Another member used plastic 'beer pong' balls from ebay. I want to say it takes about 900 ping pong balls to fill a SJ.

http://www.ebay.com/itm/1152-BEER-P...573?pt=LH_DefaultDomain_0&hash=item51ac4743ed

http://www.ebay.com/itm/576-BEER-PI...320?pt=LH_DefaultDomain_0&hash=item43b7028c30