Running out of epoxy for kit kayak build

Is it fairly common to run out of resin/hardner on a kit kayak build?

I'm on my first build of a Sectional Shearwater Sport. I've completed the interior work (glassing cockpit, fillets, etc.) and am moving to exterior work (glass deck and hull with fill coats, etc.). My assumption is that I should be about halfway through my epoxy material at this point. The kit includes 6 quarts resin and 3 quarts hardner, and I only have about 1/4 of that left now, leading me to think I need to buy more.

As this is my first build there are probably some inefficiencies in the way that I'm batching epoxy mixes, but I'm still trying to be quite frugal on my use of the material. For example, I'm following the instructions closly regarding the suggested radiuses of fillets and avoiding pooling. It's worth noting that the Sectional version of the Shearwater Sport uses a lot of epoxy on the bulkheads relative to the normal Shearwater Sport. The bulkheads recieve glass on all (4) sides and 1" radius fillets where they join the hull. This is certainly understandable for sectional structual integrity, but it does leave me wondering if the kits include enough epoxy for this version to accomoate. Is my experience here fairly typical?

I'm also wondering about the upcoming end pours. The instructions call for a cup of epoxy on each end. I assume that's a literal "cup" (measuing cup), but that's a lot of material and still does not seem like enough to fully enclose loop holes. Does anyone have any tips on how to mange material for these end pours? I'm considering some of the micro ballon filler, but not sure if it's worth the trouble.

Thanks for any tips and insights!

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RE: Running out of epoxy for kit kayak build

   I have built a Sassafras canoe, a Skerry, and a Kaholo SUP and I've run out of epoxy on every one. On the Kaholo it was only by a little bit and I had some leftovers I used. The other two I bought a small extra epoxy kit. After I realized I was short. Both the boats are a bit overweight and I'm sure it's all excess epoxy. You have arrived as a  builder when you nail John's spec weight for a boat. 

RE: Running out of epoxy for kit kayak build

Whatever else gets posted in reply to the points you've raised, I emphatically urge you NOT to use microballoons for structural 'filler'! That's not at all what it's intended for.

Unthicked epoxy's fine for these end pours while acknowledging the tendency for the volume of mixed epoxy used to 'cook off' rather quickly once in place. Some folks even stand the ends of their projects in buckets of cold water to keep exotherm from literally boiling the epoxy if ambient temps in the build space is high. Adding microballoons - an effective insulator in deep-section epoxy builds - increases the speed at which exotherm takes place.

New users of epoxy tend to end up buying more when they realize they're running short; the quantities included with kits have been arrived at by skilled assemblers who know how much is requited for the operations contemplated. Nothing to be ashamed about, just part of the experiences of being new to an endeavor.

RE: Running out of epoxy for kit kayak build

Hi Rj, 

thought i would jump in here as well.   

it's not atypical to need to buy a bit extra but as mentioned above, they definitely provide enough as you get more experienced.   there are also particular designs (like the sectional) where there is less margin.  also, you obviously never want to totally run its also not unreasonable to ask about getting more vs testing how a near-empty epoxy jug behaves.

i have been a serial builder and now routinely only use about 2/3 of what comes in a kit to get the job done.    so i only put tha out as a reference of the art of the possible.  

on your question about end pours.  if you have not already attached the hull to the deck, i would do your end-pour while you still have the boat apart.   your goal on the end-pour is simply to ensure that if you drill a hole for the a grab loop....that it does not open up/allow water into the boat.   you can make the end pour much smaller (and use less epoxy) by doing this prior to the placing the deck on.   and yes, you can also use micro-balloons (or even a block of wood) for end-pours....they are not structural.   

in this approach, you would mark where you want your grab loop hole to be, then make/place a dam with scrap okoume covered in duct tape just outside the edge of the planned hole (i go only about another 1/2 behind the planned hole), and then make a thickened (peanut butter consistency) paste of epoxy and microballoons (you can also use woodflour) and trowel it into the tip of the boat with the dam holding it in place right at the ends.

below is a picture showing an end-pour (in this case wood epoxied into the end) installed into a hull prior to putting the deck on:

i then go ahead and actually drill the hole for the grap loop prior to assembly so i can confirm that the hole does not open up into the hull (see below)

anyway, i hope this is helpful.


RE: Running out of epoxy for kit kayak build

Same thing for me, 20 years ago I used double the epoxy that came with the kit, today I have leftovers.

Endpours are structural but it's OK to use microballons because the forces they have to resist are mostly compressive, which microballoons are excellent at resisting. Unthickened epoy is very heavy by comparison, as well as expensive. So even if you weren't running out I wouldn't recommend unthickened.

My favorite way to handle it is with a wooden stem/stern piece instead of an endpour. With the right wood it's lighter and/or cheaper than an endpour and lets you bank a pretty good margin of epoxy for the rest of the boat. And the wood doesn't have to be anything special or particularly well-shaped. For my WD12 I used some scrap pine 2x4 and pieces from a tangerine crate that I had laying around  and bedded them in epoxy/woodflour putty. It doesn't look as nice as Howard's, but only the spiders see it :-) But it does have to be done before the deck is put on. Something to keep in mind for the next boat.

Good luck,


RE: Running out of epoxy for kit kayak build

   I'm also building the Shearwater Sport Sectional, and I did need to buy some more epoxy, but only for the third exterrnal coat.  I did have to redo a section of the fiberglass when the epoxy didn't set, and had a couple of cups harden while I was working, so I think I might have made it with the provided quantities otherwise, but it would have been close.



RE: Running out of epoxy for kit kayak build

Thanks all! This is a great mix of feedback.

Based on these comments I feel less defeated for running low on epoxy. I also agree that there is likely less margin for the Sectional Shearwater. I'm going to grab a couple extra quarts and carry on. No matter what, this thing is certainly going to be much lighter than an equivalent-size comsumer boat.

It's also interesting to see the variety of ideas around end pours. I really do like the idea of knocking those out before fusing the deck, but unfortunately that's not an option for this build as my deck is already forever in-place. I also suspect that pre-forming a fill up there could make for trickier tolerances when finally fitting the deck (e.g. potential for gaps between the fill and deck). So for first-time builders the "pour" method may still be the way to go. For any future builds however, I suspect I'll be experimenting here as higher efficiencies and weight reduction seem more achievable with experience.

I may still experiment with various filler strategies for the pour material, and I'm also now thinking about letting to pour set outside where it's cold (but bringing it inside to fully cure) to minimize burn-off of that high-volume concentration.

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