Core foam update

[ripvan1]

For any who may be interested it is also known as foamboard and on googling had several hits giving art supplies shop as suppliers. Popped into Southsea art shop got 10mm sheet A0 (33" x 46") for a tenner - it's rigid high-density stuff but with enough bend in it to do the curve of the "ceiling" - will attach with contact adhesive unless anyone's got another suggestion

 

[pvb]

I think you're probably wasting your time. Foamboard from an art shop isn't likely to have the structural strength you need for your coachroof. It's a big messy job, and you surely only want to do it once?

 

[ripvan1]

Well pvb, it's closed cell foam, high density and slightly flexible - less brittle than the 50 year old stuff I've removed - it's not structural, beams will provide strengthening - it's to replace what I've removed already so the getting into a mess scenario has already been breached.

I don't see how much mess can be generated from gluing a piece of foam to a bit of fibreglass then encapsulating the foam -

Any replacement of fittings will be backing-plated.

 

[pvb]

OK, it's your boat, so you call the shots. Hope it goes well.

By the way, most artshop "foamboard" is polystyrene, which will probably dissolve in the resins used in fibreglass.

 

[ripvan1]

By the way, most artshop "foamboard" is polystyrene, which will probably dissolve in the resins used in fibreglass.

Just what I've taken out ! sigh

 

[vyv_cox]

Composition seems to vary. The 'Foamboard' website says their product is polystyrene, whereas Robert Horne say theirs is PVC. Some are card faced and you may well be able to attach the cardboard side to the deck head using contact adhesive but polystyrene will dissolve in the solvents.

Whether cardboard faced material is suitable for use in a boat is another matter altogether....

 

[lustyd]

How does the price compare to the stuff here?

 

[boatmike]

Composition seems to vary. The 'Foamboard' website says their product is polystyrene, whereas Robert Horne say theirs is PVC. Some are card faced and you may well be able to attach the cardboard side to the deck head using contact adhesive but polystyrene will dissolve in the solvents.

Whether cardboard faced material is suitable for use in a boat is another matter altogether....

I would suggest you need to be a little cautious with regard to the board you have found regarding it's suitability. At the very least prime it with resin on both sides first and do a test. Any cardboard surface must be removed. Regarding sticking it up with contact adhesive, I would not. you need to use a properly formulated resin for this purpose or it will delaminate. As I said previously "crestomer" is the best but suitably filled thixotropic laminating resin will do. At a pinch car filler paste will do the job. It's only PE resin with a filler but an expensive way to go if the area is large. You do need a mechanical support for it while curing if working uphand and unless you are able to vacuum bag it you need to "prop" it up with supports from underneath. Often the easiest way is to screw battens over it fixed to the good laminate around the area. you can jam wedges under the battens to the foam locally. Whatever you use to stick the foam to the outer skin needs to be applied generously and it's a good idea to drill 1/2 holes through it at regular intervals so that the paste can be seen to extrude through the holes as you apply pressure from underneath. These holes will also help to form mechanical ties between the two outer skins.

 

[boatmike]

How does the price compare to the stuff here?

Good find. I would certainly use this in preference to any doubtful stuff from an art shop

 

[lustyd]

Good find. I would certainly use this in preference to any doubtful stuff from an art shop

Funnily enough I thought all boaties would have known about that site. I actually realised that there's a directory of all this stuff every month in YM the other day too. I kicked myself having spent so much time on the internet searching for things!

 

[PCUK]

So is the CFS aerosol foam also closed cell? That would be very useful!

 

[lustyd]

I don't know but the 2 part stuff seems to be.

 

[ripvan1]

boatmike and lustyd, thanks for your informative posts, i will certainly try a test area with different ways of fixing my dodgy stuff. it would appear that original polystyrene was glued and only rotted away where wet - wonder what was used to affix