Fiberglassing an open framework?

Does anyone have experience with laying up a fiberglass hull and deck over an open framework?

I have an oportunity to acquire an old Folbot Sporty kit. I’m thinking of building it as a dedicated fishing yak but the kit is 20+ years old. The kit is complete, however the rubberized fabric has suffered some in storage and the manual only gives it a 30yr lifespan anyway.

I have some experience with fiberglass and epoxy but only laying it on solid surfaces. If glass cloth is stretched and pinned to a wood framework will it loosen and sag when wetted out? I have a suspicion that it will.

Any ideas on how to get a first layer of glass/epoxy on a wood frame without a messy and nerve wracking session of tugging and pinning wet cloth?

Appreciate any thoughts.


Don’t do it.
You’re better off making a new skin.


– Last Updated: Nov-05-05 6:48 AM EST –

Are you trying to use the fiberglass as the "skin?" Kinda defeats some of the attributes of a SOF -- light weight and a certain amount of forgiving flexing.

If you are using the frame as a "plug" for a composite boat, then you still need to stretch some sort of skin over the frame to provide a surface that the glass/epoxy will take the shape off. Otherwise, the glass will sag between the framework with the weight of the epoxy. Stretch the skin over the frame, then layer plastic wrap over the skin before the glass and epoxy job. When the glass/epoxy hardens, you can peel it right off the plastic.

If you want to just replace the skin, you should go over to Tom Yost's site. Tom is a bonafide expert in making folding skin on frame boats. He has plenty of information on various rubberized skin material. I forget what his site address is. You can find it my googling "Tom Yost, skin on frame kayaks."



– Last Updated: Nov-05-05 8:21 AM EST –

Dacron has been used in this application, but you would have to probably lace back and forth between the ribs with a non stretching cord. This site better demonstrates -

If you feel a need to go fiberglass I wouldn't glass directly to the ribs because the glass will sink a lot between the ribs when you wet it out with resin.
You could cover the frame with shrink wrap plastic (Home Depot - sold for covering glass slider doors) attach it to the frame then shrink it tight with a hair dryer. Glass over that with epoxy resin (should work with polyester as well as, but I would test it first as I have never tried that) then lift the glass hull off of the plastic as the glass won't stick to the plastic after it cures. Then coat the ribs in resin and stick them back into the glassed hull. I have made two boats this way by making a frame with pvc pipe for stingers to create the form and layed up enough glass so I didn't have to have the frame as part of the boat.

Thanks for the suggestions. Even the “don’t do it” one. :slight_smile:

I am curious if the reasons behind “don’t do it” are esthetic or just pessimistic about the likelyhood of success. I do feel a tinge of guilt for wanting to radically modify what is, afterall, nearly an antique. Not quite enough to stop me from doing it though. :slight_smile:

The thing is I’m not all that comfortable with using a fabric skinned boat as a knock-about fishing craft. The intended waterway is often littered with debris that would not be kind to a fabric skin.

The idea is to fabricate a specialized kayak for April/May striper fishing on the Hudson. I figure the Folbot’s 32 inch beam will be a very stable platform. Since I already have two touring boats it’s not likely I would use the Folbot for anything but fishing.

The dacron geodesic is an interesting technique but looks a little too delicate for my intended use. Shrink wrapping the framework to create a base to layup fiberglass sounds like a possibility. I’m also thinking maybe some type of foam/balsa core might be the way to go.

Anyway, thanks again for the suggestions and links. With all the other projects I’ve got going it’s probable that kit will sit in storage for another year at least.


The Yost option is a good one. I looked
into it for a friend and it appeared to be the best way to reskin a folboat. By reskinning, you get the added benefit of having a breakdown boat that you can pack in a small space if need be. Other than that, for fishing get a plastic kayak, sit-in or SOT. Probably less expensive than glassing the folboat, a hell of a lot less trouble, and you can easily outfit them for fishing with rod holders, fishfinder, etc. without much difficulty.

Thanks again.
Just though I should mention a couple other things.

The Folbot Sporty kit is not a “folding” kayak. Once constructed it does not come apart. I would not be sacrificing portability no matter how I build it. The original kit produces a 15ft boat that weighs about 60 lbs, so a glass version in that plus/minus range should not be structurally compromised.

The kit was purchased by a relative many years ago and never assembled. It’s being given to me. I don’t “need” a fishing yak so the economics of buying one rather than building one do not exist. Building this kit, either in original materials or radically modified, is something I will do for fun not necessity.

Thanks again to everyone who contributed their thoughts.


Do Contact Yost!
he is absolutely forthcoming in sharing information on his avocation with design and construction of SOFs. His use of various modern rubberized fabrics will apply in your situation and would probably be easier and cheaper than doing multilayers of glass/epoxy.


This might work
Use fiberglass tape. Pull it through a bath of resin and stretch over the boat one piece at a time creating a base to lay the cloth on. You should be able to pull the individual tapes taught enough so they don’t sag.

Keep it a SOF
I’d suggest covering with fabric - nylon or dacron, using the techniques for skin-on-frame building. Go to and look under “Kayaks, Paddles, Gear”. You will find several good books on SOF building, including instructions on skinning with fabric and sealing with polyurethane. I used

Chris Cunningham’s book, but Morris and Starr are both good, too. Finally, if you use Yost’s method, you may still have a folder!

Fabric first, then fiberglass
While I agree with the others who suggested that your best bet is to make a new skin a la Tom Yost, there are other methods you can use. The frame can be skinned in the standard skin-on-frame method with either polyester or Nylon. Once it’s skinned, you have several choices:

  1. You can coat it with polyurethane, as is typically done on SOF kayaks.

  2. You can coat it with Hypalon or Neoprene, as George Dyson does on his boats.

  3. You can coat it with epoxy, as Nick Schade and a few others have done.

  4. You can coat it with epoxy, then fiberglass over it if you REALLY want a fiberglass boat.

    All of these methods will result in a boat that cannot be folded, but a Hypalon or Neoprene coated skin can be cut open, removed and modified to allow the boat to be used as a folder.