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

[227]

REFOAMING WITH OEM STYLE NOSE FOAM

I have been avoiding that terrible subject of removing and replacing my water logged hull foam for as long as I can now, but its finally caught up to me. This is a nasty job, and I only want to have to do it once, so after reading several threads of all the pros and cons for refoam options, (Ping pong balls, expanded Polystyrene, etc) I decided that the best option would be to go with the same foam as the OEM nose piece is made of, as it is both water and gasoline/oil proof. After some exhaustive research, I finally found out exactly what type of foam that nose piece is made of. The Foam is called "Beaded Polypropylene" (BPP) I believe it is also called "Expanded Polypropylene" (EPP). Like already mentioned, Polypropylene is a closed cell foam which is both water and gasoline/oil proof. It looks identical to expanded polystyrene, except it is slightly heavier. When I say slightly I mean oz not lbs. It cannot be poured like a two part foam, as it comes in a sheet, so it will have to be custom cut/fitted into the rear cavity of your ski when doing your refoam. From the quotes I've received, enough BPP Foam to do a ski will cost around $50.00 which is cheap considering you will only have to do it once. For all you scavenger guys on a budget who live near the beach or a junkyard, BPP is the same stuff they use for body board cores and it's also used in the bumpers of newer cars.

To learn more GOOGLE Polypropylene or read about it here
http://www.epp.com/

You can get it here

http://www.usplastic.com/catalog/item.aspx?sku=45707

Or here

http://www.markofoam.com/

 

[Iland Trader]

Great research! another good place to look would be an architectural foam supplier for blocks of EPP to carve... Ive previousle purchased 2 cubic foot blocks for projects Also, just to clarify because Ive done the ball mod myself- we don't use ping pong balls, they actually degrade over time into a slimy ooze. Beer pong balls however are a completely different plastic composition and are the thing to use- they wont break down over time in water.

 

[Watty]

You can also buy the BPP beads themselves in bags. Also very handy for filling any little spots that you can't be assed shaping to. What I like about The EPP method is that you can do the entire floor area, and then through the access holes of your foot holds can pack the stuff right up and around the holds themselves and have a perfect fit when you install. I'm doing this myself right now, only we pay $120 for a 1200x900x100mm sheet. This IS the way to refoam! You've done a good thing by sharing! Now, if we could fill the entire area of the rear of the ski with the BPP beads, seal it off and form them will pressure and steam, we'd be sweet!

 

[227]

Good call on the beads Watty. Unfortunately you can't just steam press the hull full of them, that would make things really easy. But as far as I know that can't be done, so any one re-foaming with Polypropylene will have to hand trim/fit from a large sheet. With that method, there will inevitably be some voids to fill, so compressing loose beads in the voids should work well . I googled Polypropylene beads and got several suppliers, but you can most likely get the beads from the same source as you buy the sheets.

 

[sjetrider]

2 part pour foam gets everywhere and even adds a little structural value. Why waste time on anything else?

 

[Matt_E]

2 part pour foam gets everywhere and even adds a little structural value. Why waste time on anything else?

Because it will inevitably soak up water.

 

[blaster800]

If we all thought that ''^ Post 5 '' way , we would still be riding stock skis and nobody would even be riding in the surf ! . And theres nothing wrong with 2 part foam either

 

[chriselmore_1]

I don't get it????

 

[Cannibal]

It sure would be nice if someone were to take a mold rear bottom deck, send it to one of those companies that make that stuff and have them make us a molded EPP insert. Even if it just fit the bottom deck, then just use some EPS for the sides, that way it fits both RN and SN. If I didn't have so much on my plate, I'd investigate more.

 

[227]

It sure would be nice if someone were to take a mold rear bottom deck, send it to one of those companies that make that stuff and have them make us a molded EPP insert. Even if it just fit the bottom deck, then just use some EPS for the sides, that way it fits both RN and SN. If I didn't have so much on my plate, I'd investigate more.

Already thought of this idea, and I will be inquiring with my suppiler if an old hull can be used as a mold. Shouldn't be to hard to find a trashed donor Hull. I know where a couple of Squares are right now. The main problem is how much it will cost to do this, as not a whole lot of people have shown interest, only 9 posts so far, and half of them are from me.

 

[nightrider05]

I don't get it????

What is there to not get?

There are various types of foam...some that suck up water like a sponge, and others that don't. This is one of the options that don't suck up water. Refoaming a ski is a dirty time consuming process...nobody wants to do this just to have their ski waterlogged the next year.

Do this mod, add drains and you are good to go for years.

I will be looking into this method next time I refoam.

 

[willcastner]

Im am very interested in this. Doing a refoam soon. If there is not a completed mold done by the time I do it I will just be buying sheets and doing it that way. You think this stuff has enough support for the tray like the pink insulation board does?

Will

 

[OCD Solutions]

What would be wrong with using a bag of these polystyrene beads?

Should my hull ever start to take on water, my plan has always been to stand my ski on it's nose and simply pour them in. 4lbs for 3.5 cu/ft for $15. It wouldn't be too heavy but would still displace more than enough water to maintain adequate bouyancy.

 

[Berky]

PS Beads will take on water if there's pressure it must be over 2lbs cu ft. and will dissolve in fuel . The stuff PPB John and Watty found kicks ass .

 

[blaw140]

2 part foam soaks up water?

Because it will inevitably soak up water.

Will it really soak up water eventually? Why?

 

[Quinc]

Already thought of this idea, and I will be inquiring with my suppiler if an old hull can be used as a mold. Shouldn't be to hard to find a trashed donor Hull. I know where a couple of Squares are right now. The main problem is how much it will cost to do this, as not a whole lot of people have shown interest, only 9 posts so far, and half of them are from me.

Any luck with this?

 

[MikeyB]

Good call on the beads Watty. Unfortunately you can't just steam press the hull full of them, that would make things really easy. But as far as I know that can't be done, so any one re-foaming with Polypropylene will have to hand trim/fit from a large sheet. With that method, there will inevitably be some voids to fill, so compressing loose beads in the voids should work well . I googled Polypropylene beads and got several suppliers, but you can most likely get the beads from the same source as you buy the sheets.

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?

 

[BrightE's]

Will it really soak up water eventually? Why?

I have a background in plastics engineering, not so much the organic chemistry part, but my best bet would be because it is a semi-rigid material, and more prone to drying and cracking with age (thus no longer being closed cell) and absorbing water. I believe polyurethane also has a higher likelihood of being attacked by fungal and bacterial agents than the more inert polyolefins (polyethylene and polypropylene). Polystyrene is more resistant to breakdown than urethane over time, but like others have said, it is easily dissolved by solvents (gasoline, acetone, etc.)

I bought my EPP from the guys over at www.flyingfoam.com, I think I spent about $96 including shipping for ~4300in^3 of the stuff (1.9# density). Which is looking to be more than enough to fill the tray, and I probably could have gone with less.

 

[Vumad]

It sure would be nice if someone were to take a mold rear bottom deck, send it to one of those companies that make that stuff and have them make us a molded EPP insert. Even if it just fit the bottom deck, then just use some EPS for the sides, that way it fits both RN and SN. If I didn't have so much on my plate, I'd investigate more.

Already thought of this idea, and I will be inquiring with my suppiler if an old hull can be used as a mold. Shouldn't be to hard to find a trashed donor Hull. I know where a couple of Squares are right now. The main problem is how much it will cost to do this, as not a whole lot of people have shown interest, only 9 posts so far, and half of them are from me.

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.

 

[swapmeet]

To answer a earlier question: I found when refoaming my ski with the purple hardware store sheet foam, standing the foam up vertically, vs. laying it in horizontally gives more support in the tray.