Experimenting with Polystrene Rigid Board

Hello ALL,

I want to do some experimenting and testing my skills, if any, in fabricating some foam panels with a decent roll on gel coat finish.

I want to use DOW polysterene rig Blue Board or some other cheap foam board to build a "dash helm panel" for a new boat.

Again, this is an experiment. The edges will be rounded. I'll putty up the panels, glass a couple of layers of mat, sand fair smooth and gel coat.

I bought enough various supplies to do the experiment. ALL products are vinyl esther.

I've done some reading on using polystyrene as a "core" and the initial glass coat needs to be epoxy. Correct? poly esther resin has styrene in it and will melt the polystyrene correct?

OK, If I bond and glass the foam panels together with epoxy based resin and bonding putty I will be able to apply the ploy esther products over the epoxy and finish with poly esther gel coat correct??

If the panel comes out looking "great" and is the right size, could the piece be used in a new boat build?

Can polystyrene be used in "light load areas" on a boat in place of say divinycell H80 core???

Thanks,

Reelpleasure

 

hey rp, FWIW, I bonded up some blue board between layers of 3mm okume, and it seems to be OK, for a console.

I roughed up the bb with a paint roller with some drywall screws screwed into it with the points of the screws just sticking out a few mm, and it seems to be holding up so far, though I havent hit the water yet. (gotta take the plastic film off.)

Didn't try radius bit, I just cut a radius curve into a squeege and ran some bog along the edges, then glass tape.

http://www.boatdesign.net/forums/boat-building/kurt-hughes-daycharter-36-a-31846-17.html#post595792

 

No, you can't apply polyester products over the foam directly, it will dissolve it. An epoxy coating will protect the foam, but it will also make the polyester bond to the epoxy quite poor, as polyester doesn't stick well to it. You can use a "tie coat" which will improve the polyester bond or you can use a epoxy based gel coat (yes, they have this now). Of course, these panels would have to be very lightly loaded, because of the shear strength of the foam, as you've pointed out.

 

polystrene foams for for isulation not for bulding structure from . They will carry next to no load what so ever so dont wast your time and money using the stuff . you dont have to use H80 FOAM !! its one of the harder grades pick on H55 or even lower and use a hot glue gun to stick the foam panels together to get your shape etc etc . if you choose a 6 mm thick sheet foam then you can use the foam as the cor and glass bothsides but remember the foam is soft and will compress if you try to insert gauges and tighen the clamps to tight .
Easest way i found is simply make glass panels and forget about using any foams ! make the panels with 450 csm eachside of 3mm core matt and then cut your panels out of that and spot hot glue together and then gently glass up the inside first and the cut off the hot gue outside and glass the outside . its quick easy and vertually no waste if you think carefully about what you are doing .
If you lay the glass to make the panels on a shiney waxed surface you will have one side smooth and shiney and have just a small amount of sanding and filling and 90% of the glassing together can be done behind so its never seen .

Over the years have built whole decks on boats up to 22 foot long including motor wells and side decks with coamings plus two person consoles using that method and its worked a treat . saves materials and mess and you see straight away what you making if it works or not !!

 

I don't see why your technique wouldn't work. You're right in using epoxy.

My engine is sitting on foam stringers, reinforced with some ply to give the engine beds something to clamp to. Solid as can be in there. Of course there is 3/8" fiberglass layup for strength. The foam was just a form for the glass. It seems to me the principle is the same, just a difference in the load and the amount of layup necessary.

 

The foam only has to carry the shear loads of the panel. These are typically an order of magnitude less than the faces. I haven't been able to find data on Dow extruded polystyrene but I would assume about 20psi shear and compressive strength for the 2lb/ft3 variety just to be safe.

Dino

 

I may do my experiment out of rigid urethane foam panels and use ployester products

 

I have made many hardtops with blue or pink foam. The slabs of large buildings are poured right over the foam and lasts for decades. There are different densities, even though the stuff you get at the building supply should be fine.
http://www.owenscorning.com/worldwide/admin/tempupload/pdf.077_HighDensity_E_1.pdf

 

You just need to use you imagination a little !!

Your missing the point of foam stringers ,once the foam has been covered with glass the foam serves no useful purpose at all as it was just there to form a shape to glass over thats all !!,in actual fact its a bit of a curse as it soaks water overtime and adds extra unwanted weight to a hull and the water can soak from end to end over its total length and can be quite a amount of extra unwanted weight !!

Building shapes from glass panels is really quite easy !! Its just like building out of plywood panels except its glass and is much easyer to work with and you see instantly what you getting . Consoles and dash panels are a breeze can mock up a whole console with foot rests and curved dash etc etc side panels ,steering wheel mounts ,screen recesses etc etc ! to get nice radiuses just make parts of shapes over plastic pipes the size you want . when its all glassed inside and finished outside it can look just like it came out of a fibreglass mould !

 

Polystyrene foam won't absorb water. It is used below grade and lasts for decades with no coating. Also, the compression rating is quite high. Check out the links to the technical data I posted.

 

Thank you Gonzo.

Here's the specs for the inexpensive stuff I used from Home Depot. Perfectly fine for the boat.

http://secure.owenscorning.net/Portal/uploads/document/20051110/43522-E.pdf

 

I've heard that a lot of competition windsurfers use the stuff over here in Greece to create custom boards and have great success. I haven't heard complaints with water absorption, etc.

 

Hi , im not familiar with Dow Blueboard. What is it, stuff from the home improvement store? Productiom foam cores I know and use are Kelegecell, bought out by Devinycell. They are pvc foam core - Absolutely non biodegradable. Urethane foams -like the kind injected under floors of small boats are apparantly not closed cell and do absorb a certain amount of water--And fuel. Ive dug plenty out of old heaps that I have replaced stringers and transoms on when I unfortunately had to do those type of gigs to pay rent. regular old styrofoam--polyester will instantly disolve - you cant even stick a couple pieces together with bondo, but thats what most surfboards are made of--with a epoxy and cloth layup encompasing it.

 

One scheme I have been thinking of trying is a quickie pickup bed tonneau cover mold made out of home depot pink foam held in shape with some ribs on the bottom side and the edges turned up and covered in metal tape. Ide do several coats of car wax wiped on and off, then a pva skin sealing it before gelcoating . I got a piece of the foam at home i've been meaning to run a test on to see if it works.