DIY fiberglass, where/how to start?
 

I need to make a new forward hatch for my sailboat. It's about 2' by 2' with a 2" lip the whole way around. Here is a sketch done by a professional artist, using the high-tech drafting software (MS Paint)

http://forums.pelicanparts.com/uploa...1212504505.jpg

I remember seeing online where a guy would make his shape out of cardboard, then apply layers of FG to both sides. He even made reinforcing ribs out of cardboard, and would glass those too.

Seems like something I could tackle, but I have never, ever played with FG. Where do I start?

Fiberglass for dummies, please

http://westsystem.com/

Lots of examples under the 'Projects' tab.

Look on the west systems site

Lots of how to in their projects site

http://westsystem.com/

do you have the old hatch? I like to make a mold of the existing stuff - then modify it the way I want to

West Systems Epoxy is expensive - I tend to buy alot of my epoxy here: http://www.fgci.com/index.html

Have you heard of this method?


http://boatdesign.net/forums/showthread.php?t=18813
There are similar projects in the boatdesign.net forum, do a search.

Alternate methods...................

Link-2:
Thermoplastic Construction
http://boatdesign.net/forums/showthread.php?t=21403&highlight=hatch

Link-3
Cabin siding material search
http://boatdesign.net/forums/showthread.php?t=20819&highlight=Kydex

+3 for Westsystem. I have built parts for three airplanes using it. I have their book on boatbuilding along with several smaller publications. You could use foam as a core and glass over it or you could use thin Luan ply as the cover piece with wood or foam stiffing ribs. You could use a flexible piece of waxed sheet metal to lay the initial top piece out on then add the stiffening ribs. Cored construction with thin layers of glass on the outside is always the lightest way to go, but there are bunch of ways you can go about this.

FWIW, if you use epoxy vs traditional polyester resin, you can use simple blue or white foam as a substrate/form/core whereas traditional polyester resin (the stuff at auto zone in a gallon/quart can) will eat thru/melt the foam.

The "pump" method by West Systems is awesome, and you should be able to pick it all up at your local hardware store (if it's a good one).

Near water I'd use blue or pink rigid insulation as the core (extruded polystyrene - closed cell).

The old hatch is a piece of crap made by the PO out of 1/4 ply with one layer of FG. It's ugly, doesn't fit right and is now cracked along the seams.

I'll dig through the westmarine "projects" site, thanks for that link. I haven't found quite what I'm looking for though. What I really have in mind is making the basic shape out of cardboard or masonite, and then glassing it on both sides, with reinforcing ribs. I've seen that online before, but can't seem to find it now that I need it.

Foam would work and would be easier I guess, but I'm worried it would be too thick... I think 3/8" would be as thick I could use for a core without having it look clumsy.

Someone told me epoxy is only necessary if you're doing repairs... ie trying to adhere to something. Is that true?

How many layers should I put over whatever "core" I use?

You also might consider marine plywood covered in a layer of glass. Then cover with a few thin coats of epoxy, then a couple coats of UV safe varnish. Strong as hell and pretty.

I have a project I'm thinking about and wondered where should I get the foam for the project? Home Depot/Lowes, or some marine supply stores?

Hey Jake, I'm sorry for the highjack! :)

Thanks Chris! :)

Oooh, that stuff is pricey. :eek: Mine isn't a marine application, just something for outside on the terrace.

I may go this route for version 2.0, but at this point:
1) cutting & shaping the plywood in such a way that looks presentable would add too much time to the task. This part will only get a couple years use before I make version 2.0
2) the boat doesn't have any other wood trim, so it would look out of place


Not at all! I was wondering the same. In fact, anyone with FG questions please jump in, you'll probably think of questions I'm not smart enough to ask. Hijack away!

You can get the sculpting foam from www.fibreglast.com/

It's amazing what someone can knock together in their garage

http://rennlight.com/hardtop/5000284i.JPG
http://rennlight.com/reflector/5000288a.JPG
http://rennlight.com/duct/5000173b.JPG

You can use the pink or blue foam from home depot = just test it first with epoxy.

Epoxy is expensive - but easy to work with and very strong. It will adhere to just about anything = which makes it better for repairs.

What kind of boat Jake? Maybe you can find the same one locally and "splash" the same hatch.

You can also get end grain balsa (or one of the Nida core or core cell foam) that you can form to just about any radius - then fiberglass/epoxy over - both sides

You'll save a lot of work by making a female mold of your part. Anything formed over the top of cardboard, etc. will have a lot of surface finishing to do. A metal or plastic form of the top portion of the cover will be the best way to start. Just wax it thoroughly and laminate right to the metal. AFA the sides, more metal or plastic simply taped securely in place will give you the 4 sides.

You could hot glue the form in a band sawed plywood cradle for stability. I make lots of molds. That one is a POC.

It's a '71 Chrysler 22... not a very common boat. There used to be another one in town but it sold last year.

Whatever I decide to use for a core... plywood, foam, balsa... how many layers of cloth should I lay?

what my main hatch looks like -

http://forums.pelicanparts.com/uploa...1212501964.jpg

I would do 3-4 layers of 8 oz cloth or 3 of 10 oz on each side. Depends on the length and width (and core material) - the wider the hatch the more layers I would add for strength.

If weight is no concern, maybe you can simply rework the existing hatch and glass over it. Might be easier to use a starting point than starting from scratch. As far as layers required, it is kind of hard to say without knowing how thick the core is and how the ribs are constructed and whether or not it gets walked on etc etc. With a core, I would think you should at least plan on a couple of layers of woven cloth, but I really could not advise you any further on weight of cloth or number of layers with out seeing the application and then doing some head scratching and guess-timating.

I have exactly the same project. 1 piece of Okoume, http://www.clcboats.com/shop/products/supplies/plywood_cedarstrips/0000-OP000.html , covered in 1 layer of cloth, http://www.clcboats.com/shop/products/supplies/epoxy_fiberglass/0000-FC000-4-50.html . Then cover in epoxy, I actually prefer MAS, but West works fine too (but stinks!) and varnish.

You might want to make the door in 2 pieces.

Great info, thanks. As much as possible, I'm trying to avoid making a mold.... but that make it sound pretty straighforward. I wouldn't have though of using steel for a mold.

Jeremy, thanks for the tips.

For now I'm just doing the small forward hatch. I really don't care if it's rough, my plan is to modify it later (or make a new one) to incorporate a solar panel.

Over the winter, I do plan on making a new main hatch, as well as a new sliding kitchenette. For those, I'd really like to use molds to make perfect shapes and get a great finish. For now, I am just shooting to get a feel for the materials and to get a quick project out of the way.

It can look like peanut butter spread on cardboard, and it will be an improvement over what I have now. I just need something I can stand on without ending up in the v-berth.