How necessary is full cloth and epoxy covering?

One of the biggest ‘put-offs’ in building is the amount of sanding that has to be done to the epoxy/ glass-cloth covered hulls and decks.   Just thinking about it exhausts me, and the topic is dealt with so often in the excellent forum posts that it is clearly a major issue.   Can we go right back to basics?   In a typical stitch-and-glue kayak such as the CLC designs, what is the purpose of covering the entire craft with cloth and epoxy resin, only to then have to sand much of this off?    I can understand the desirability of having this added strength for abrasion-resistance along the entire keel area, to protect from damage when launching or retrieving over sand or rocks or gravel, but is it really absolutely necessary to cover the entire craft – deck and all - with cloth and epoxy?   Is it necessary for structural (strength) reasons, or just ‘traditional’ to do it this way?   Would it produce a hull of sufficient structural integrity for protected-waters paddling if only the keel line was so finished, and with the sides of the hull and deck merely finished with a soaked-in thin epoxy coat with no cloth?   This could presumably then be painted or varnished in the usual manner.   Or if just the hard chines and hull-to-deck join were taped and glassed? It seems to me that this would not only save money and hours of unrewarding labour, but also weight. I really would be interested in some studied answers to this question, not just “well, that’s the way it’s always been done!” 

Many thanks…

BTW - what an excellent website CLC operates, and how interesting and informative the builders' forum!   I'm just getting involved and anticipate spending happy hours reading through all the posts...

7 replies:

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RE: How necessary is full cloth and epoxy covering?

Lol, I have built Chessapeake kayaks both with and without a full glass covering, and I would say that if you are building light and using thin plywood, 3mm or less, then go for the glass covering and if using 4mm then you can get away without it in your situation of protected waters like rivers and creeks etc.


RE: How necessary is full cloth and epoxy covering?


That's not the way it's always been done. The original CLC boats had less glass than they do now. As the years passed and performance history was accumulated, it became obvious that the way most people used the boats they needed more glass and the designs & kits were updated.

The more recent boats (like the Schade designs) need the glass for structural reasons. They use thinner wood to get those neat shapes and the glass keeps them from falling apart or getting gouged or punctured.

As Robert says, depending on the thickness of the wood and how you use the boat, you can get away with less than a full covering, but it's there for a reason, not just tradition. 

Now really getting back to basics, if sanding is giving someone that much heartache, they're doing something wrong. Either the epoxy/glass has been misapplied or the sanding equipment is wrong (or both). WIth proper care in application, the only sanding that needs to be done after the weave is filled is just enough to remove the surface irregularities and to give some tooth for the varnish or primer. With the proper tools (less than $100 total) that should only take a couple of hours for a 17 foot yak. I won't hijack this into a glassing/sanding how-to thread, but sanding doesn't have to be traumatic.



RE: How necessary is full cloth and epoxy covering?

I too questioned the need for so much glass before building my Shearwater, but followed the instructions and am now glad I did.  The plywood on these boats is very thin and flexible.  The glass protects it from puncturing and stiffens the flat panels.  While the epoxy is necessary to stiffen the glass, excess epoxy adds nothing but weight.  To keep weight within reason, keep your fillets to a minimum, keep your epoxy coats thin, and cut way back on the end pours.  My end pours are about three ounces each, done with the hull upside down at a 30 degree angle instead of standing on end, and they effectively seal and strengthen the hull/deck joint as well as the 8-ounce pours that CLC recommends.

RE: How necessary is full cloth and epoxy covering?

Regardless of how little glass you use, you still have to epoxy to seal the wood and no matter how little epoxy you use, you still have to sand the outer layer because it does not self level. Sanding levels it out so you can do the brightwork to finish it off.

So, 1 sheet of epoxy soaked glass or 10 coats of glass, it is still the same amount of sanding to finish the boat.

Sanding is cake with a machine.

'Shortcuts' won't get you the other end of a build to be proud of. If sanding is that bad for ya, buy a bright yellow plastic boat, but it won't give you the same feeling when you get in it for a paddle as a boat that you built and finished yourself.

If you wanna build, you are gonna sand. If you don't want to sand, you don't want to build.

RE: How necessary is full cloth and epoxy covering?

The old cliche, half of boat building is sanding (a paraphrase), is absolutely true.  No matter if you use fiberglass or just epoxy, you will HAVE to sand.  You have to sand before fiberglassing/ epoxy sealing, and after it.  One of the main mistakes I see when called in to finish people's half built boats is that they didn't sand BEFORE the fiberglass was put on.  

 I will second fishbuster's advice, if you don't want to sand, buy a production boat, or have someone build a wooden one for you.   

RE: How necessary is full cloth and epoxy covering?

Seems to me like it is also a comparatively tricky business sanding epoxy on bare wood so that it is suitably smooth, ready for varnish, without sanding into the wood, not leaving enough thickness of epoxy to prevent water intrusion? Can be done, but there isn't a lot of margin of protection from gung-ho sanding monkeys like me!


Ogata (eric)

RE: How necessary is full cloth and epoxy covering?

I wouldn't go so far as to say that the only choices are to sand a lot or get a production boat. It's perfectly possible to sand just enough to make the primer stick and paint the boat for a workboat finish. For that matter, there are paints that stick well to unsanded epoxy that has the blush washed off, so that could be a no-sand finish.

Will it look like a coffee table? No. Will it affect the boat's performance? No. Will some people give lectures about pride, work ethic, etc? Yes. But if quickly getting out on the water in a boat you built by yourself and for yourself is what's important to you, a workboat finish can't be beat.



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