Freestyle 2 part pour foam

[Dirty Jersey!]

i am looking to rocker my waveblaster and i am not sure on what to use, i was told i can use a 2 part foam but i herd it was hard to shape and was messy. i was also told i could use the pink foam block cuz it is easier to shape.....any ideas of what i should use????:scratchchin:

 

[Kawikazi]

I used the pink/green foam board from lowes. I bought a 4x8 sheet and cut, layered and toothpicked it all together. Then covered it in glass. But be sure to use a little extra hardener on first layer to cure quicker as most resins slowly melt that particular foam

 

[tom21]

2lb flotation foam is way easy to shape but is really messy. nothing an airhose cant clean up though. you can use all the normal wood or body working tools on it. in the end if you want a really smooth surface you will have to use bondo, or thickened resin, or even drywall mud to get a smooth sanded surface.

if you go the foam sheet route you might try to cover it with tape before laying up on it for some protection.

2 part expanding foam is a little more difficult to manage, but you can always pour it in a box and cut sections or make an enclosure on your part with cardboard. its also pretty expensive for a gallon.

you can also use tons of other things, formica sheet, thin veneers of wood, aluminum flashing, masonite, plastic etc. cardboard works great too. pretty much whatever crap you have laying around, some cutting tools, tape and an old A-team or McGuyver video and you can make whatever you need in between commercials.

 

[Dirty Jersey!]

thanks alot for the help and tips bro....can you put resin right on top of drywall mud without it eating through it?

 

[SuperN8]

thanks alot for the help and tips bro....can you put resin right on top of drywall mud without it eating through it?

I beleive you can use resin on top of drywall mud or plaster, never tried it however.
Why would you want to use drywall mud? if its for shaping it would add alot of extra weight and may be hard to remove afterwards.

 

[Dirty Jersey!]

it wazs just an idea that way i could get it as smooth as possible before layin on the glass but i think it so be fine once i sand the foam to just put the glass on

 

[Joker]

Use whatever material to shape it with, cover with duck tape, wax the duck tape with car wax and remove like you would a car and lay on that. It worked well when I rockered my 650

 

[SuperN8]

You shouldn't have any problems glassing over foam.

I have even used Pam (Cooking spray) to help seperate a mold from the glass, which worked quite well!

 

[tom21]

I would only use this stuff for making the shape you want, pulling that off to use for a mold and then making a part you could install and glass in. or use the mold to layup your part from inside the ski. I would not want to leave the bondo or mud as part of the ski. the flotation foam for sure could stay and help

 

[Dirty Jersey!]

i am just going to glass over the foam, i am not going to make a mold of it....if i plan on making a mold i will just copy it when i complete the whole build

 

[Vumad]

i am just going to glass over the foam, i am not going to make a mold of it....if i plan on making a mold i will just copy it when i complete the whole build

Are you removing the foam when you are done?

I don't have near the experience Tom does, so take his advice over mine.

Anytime I am working with something in which I will remove the foam or the materials I used to make the shape I want, I tend to favor 2lb 2-part foam and bondo. I may be switching to 4lb foam as I have heard 2lb shrinks and I have had lots of problem with my plugs where my foam has pulled in and taken my bondo with it.

If I were rockering a B1, where I was going to be cutting out the hull, then adding foam, glassing, then removing the foam, I would do the following...

- i would tape off the inside of the hull with packing tape (use good tape that doesn't rip easily, the foam wont stick to it) and paper in all the areas I don't want foam to stick
-I would pour 2 or 4lb foam into the hull where I plan to cut into the hull, and let it fill out from there.
-then cut the original hull, and shape my glass to mostly where I want to be.
-Once I have my shape, I would cover it with a thin layer of bondo and sand it mostly smooth.
-cut all pieces of glass and lay them out to be ready for layup
- I would be sure all the original SMC on the outside of the hull is sanding with 80grit or heavier paper and clean with acetone to have a good surface.
-I would tape off (painters tape) all the original hull so I can only see the bondo.
- then wax the bondo with mold release wax, do not use PVA.
-remove the painters tape so I have a nice clean line of waxed bondo and preped SMC
-Layup my glass
-after it is all dry, I would go on the inside of the boat, and rip out all of the bondo and foam
-sand the new glass and the old SMC, then lay up glass on the inside so the new glass makes a sandwitch out of the old SMC

Glass is fine to lay over foam. However, glass doesn't like to stick to foam. Glass will stick much better to waxed bondo which will make it easier to lay over tighter contours. Also, foam pores soak up and waste a lot of resin. Additionally, to lay up and prep the inside, you have to sand off all that resin coated foam to get a clean surface for your inside layup. If you bondo, layup, remove bondo, you get easier layup on the outside, then a nice clean smooth surface ready for layup (after sanding and cleaning) for your other layup or paint.

Edit: If you are not going to remove the foam, do not use bondo. The above method is only if you are going to cut the hull and remove the foam afterwards. I am assuming you are going to be cutting and removing to rocker.