Plywood for replacement helm door

[potoboat]

Hi all,

I'm looking at building a replacement helm door for my 73 Pearson Portsmouth. The existing door is rotted along the foot. The aluminum frames and hardware are actually in decent shape or can be easily refurbished, and the door itself is plywood, so it seems like a pretty straight-forward project. The previous door has a white laminate on the exterior side, thin and hard. I'm not sure if it's vinyl, gelcoat or something else, but I've also seen it used quite a bit in houseboat construction which makes me think it is (or was) a commonly available product. Does anyone know what it might be and how I could acquire some?

 

[SteveK]

My guess it is a sheet of laid up fiberglass. My brief stint in a boatyard job saw some done on waxed surface gelcoat is applied and then one/two layers of mat.

 

[Bmarler]

Interesting. It almost looks like Formica.
I wouldn’t do it that way. I like to fully fiberglass over the door inside and out. I like silver tip epoxy (no amine blush), then use their epoxy fairing compound and a long sanding block to make it nice and flat.

 

[Delta Riverat]

I'd say it is Formica. Looks way too sharp and uniform to be fiberglass. I like the stuff, easy to work with, standard wood working tools, extremely durable.

 

[potoboat]

I'd say it is Formica. Looks way too sharp and uniform to be fiberglass. I like the stuff, easy to work with, standard wood working tools, extremely durable.

Agreed; it is definitely factory produced, too uniform (both thickness and finish) to be a hand-laid fiberglass job. I'm not very familiar with formica other than for countertop surfaces. Do they make variants that would be appropriate for external siding, i.e. UV resistant?

 

[potoboat]

My guess it is a sheet of laid up fiberglass. My brief stint in a boatyard job saw some done on waxed surface gelcoat is applied and then one/two layers of mat.

Hmm, I suppose that might work. I've done several hand layups, including gelcoat on a waxed smooth surface like you describe. But that's a lot more work than a laminate sheet, with all the sanding and stuff.

 

[RT Firefly]

Greetings,
Welcome aboard. Mr. p. Indeed, double clad Formica would be a lot easier BUT one has to be concerned about the material being completely and 100% water proof.
Best is to get in touch with manufacturer. Laminate for the Marine Industry | Formica Group

 

[Comodave]

I made one for a trawler I had about 20 years ago. I used 1” Starboard and routed out the window. All one piece and no rot ever. Contact me if you are interested.

 

[Delta Riverat]

On the pics the only place where the Formica looks bad (cracked) is on the bottom where the wood rotted.

In Formica I trust -

Flexible, easy, and durable. Really, the wood rotted well before the laminate looked bad. For marine (outside) use if you really want durable you could glue with epoxy, but the solvent based contact cement (the stinky one) is also waterproof.

Then you go with cheap exterior plywood, laminate the Formica and call it good.

 

[Bmarler]

I wouldn’t use cheaper grades of plywood. Use marine grade so it will have no voids and more, thinner, laminations. The more glue lines in the plywood, the better it holds it’s shape.
Interesting that Dave did one from starboard. I would have thought that it might expand too much in the heat.

 

[potoboat]

I wouldn’t use cheaper grades of plywood. Use marine grade so it will have no voids and more, thinner, laminations. The more glue lines in the plywood, the better it holds it’s shape.

Agree 100%! I (nearly) always use marine grade woods

 

[lwarden]

I would make this of a epoxy laminate on top of foam core with strips of solid material like G-10 sheet. You could also use wood around the edges, but G-10 would be bullet proof. I recently did a small door like this. Fair with fairing compound, prime and paint with Alexseal. The layup can be done on a sheet of melamine so one side comes off perfect. Even better if you can get a vacuum bag over it after the layup.