layers of materials....

okay so the gel coat is colour for the boat and uv protection…the glass fiber is the stuff holding the boat together…

WHAT IS the layer that keeps the boat waterproof (for a lack of other words in my head at this moment)…

what is keeping the water out while the boat is bobbing 2 miles from shore???

where does the line get crossed about leakage through a crack/hole???

or is a combination of all the layers together???

just trying to wrap my head about this…


I’m no pro
but I’ll shoot-

The fiberglass is “soaked” in epoxy resin. This epoxy resin fills the voids in the glass strands, creating a surface that will not allow the passage of water.

Look at a modern skin-on-frame kayak sometime. It is nothing more than a nylon sheet wrapped around a frame and sewn tight. The nylon is then more or less “painted”, and this creates the waterproof barrier. Fiberglass is much the same but uses layers of fiberglass cloth instead of nylon and the resin to stiffen and waterproof.

Here’s a cross-section of gel-coat and fiberglass from a hole I drilled in a Valley Nordkapp with a holesaw. I was amazed how thin the deck was.

wow,that’s gel coat
it looks like it’s 1/4 the thickness of the piece.

fiber reinforced plastic
there’s the fiberglass cloth (the fiber) and the resin that surrounds it(plastic). The fiber is strong in tension and the resin is strong in compression. The resin provides a solid waterproof matrix that surrounds the cloth.

The least expensive resin is polyester, the better resin is vinylester. Epoxy is a whole different kind of resin that is less common and has better compression numbers but costs more.

Polyester and vinylester resins are what most folks associate with “fiberglass”. It stinks when new. Epoxy doesn’t stink when new and some people develop sensitivity to the uncured resin.



ooooh, i can’t wait
to start inhaling that epoxy…grin

read the product warnings. Although it doesn’t release aromatic hydrocarbons when curing like the other resins you really don’t want to work in a closed shop without a respirator. I know some guys who’ve worked around polyester resins a lot and they seem a little loopy,with epoxy if you get a reaction from sloppy handling and get it on your skin too much the reaction can be like getting poison oak. Seems like 1 in 100 folks get a reaction right off,some may take repeated exposure to get a reaction but once you do,that’s it. Most folks I know who have worked with epoxy a lot aren’t allergic but there’s always one or two who show up one day with red blistering sores confessing they weren’t careful and “look what happened”.

Fore or aft deck?
Just curious whether the hole you drilled was in the foredeck just forward of the cockpit where the deck is reinforced, or further forward or the aft deck which is not.

In response to LeeG’s comments…a FYI…
I just put a skid plate on my Canoe. The resins contained a potential sensitizer, a known sensitizer (HMDI, Hexamethylene-1,6-diisocyanate .005 ppm TLV TWA), and a potential carcinogen (MDA, 4,4’Methylenedianiline 10ppb PEL TWA) Some of that stuff is pretty hot, so perform work accordingly (adequate ventilation, no eating drinking smoking around it, proper PPE, etc).



– Last Updated: Apr-28-06 5:43 PM EST –

i was kidding, guys. all the epoxy talk got me excited about my upcoming build.

I drilled the hole for a bilge-pump discharge fitting. It is about 1-1/2" aft of the front bulkhead and 1" above the deck to hull seam.

which layer then is going to be more inportant for the sealing then…the innermost???so the more sand and crap sitting in your cockpit the more realistic the damage could then be???


pondering deeply…



is it that you are concerned about? The resin soaks into and around the weave of the fiberglass. It remains pliable and strong without allowing leaks.

Check out these clips from ONNO Kayaks to see what a quality glass and epoxy build can stand up against-