Hull Assembly

Floors & Bulkheads, Pt.4 – Fillets

With all the tack welds in place it’s time to remove all the stitches and lay down large continuous fillets at all the seams.


Removing the stitches is fun. Seeing everything held together and standing on its on is satisfying. Just 1,517 more steps to go.

Though I had cleaned my tack weld fillets pretty well I used a multi-tool with a FEIN sanding adapter to go over all the small fillets and knock down any epoxy globs that might not get covered by the larger fillets.

After a quick vacuum, I brushed unthickened epoxy onto any raw wood to which thickened epoxy would be applied. This to help keep epoxy in the fillets from being drawn into the wood, possibly starving the fillet.


Mixing : For tack welds I thickened my epoxy with cel-o-fil only. For the large fillets I added some wood flour but only to play around with ratios for the sake of testing color. When I get to fillets that will be exposed under varnish I think I might like those fillets to be lighter than straight wood flour. Color doesn’t matter for these fillets as they are in the bilge and will be painted over.

I began at the stern, as this was the most easily accessible location and I figured the easiest fillets to lay down.

You can see, I stopped short a couple inches from the ends. Once the hull sides are installed I’ll lay a fillet that is continuous across the joint of the bottom and side hull panels.

Next I moved forward, between bulkheads 7 & 8.

Then I skipped to the bow and worked aft, stopping at bulkhead 2.

Bulkhead 3

A post or so ago I mentioned that I was holding off installing bulkhead 3. This is because during dry fit, that bulkhead didn’t come anywhere close to flush with the hull bottoms. So I wanted to pause and do some thinking on that. I could shave down the piece until it is flush but the problem is that the top would then be that much lower than the rest of the floors. My bulkhead 2 also didn’t meet flush with the hull pieces. It’s like my hull shape isn’t quite right. I can’t see how it would be any other shape than how it is but this is bothering me a little bit.

There was no ‘pulling the panels up’ tight against the floors so I simply got everything level and proceeded with tack welds.

Now, final fillets on BH 3 and all the floors are done…

Finally I added some vertical fillets where the floors meet the centerboard trunk…

Summary Thoughts…

I have a love/hate relationship with fillets. I always look forward to laying fillets. They are really nice aesthetic pieces and when you get one right it’s a good feeling. Every time is a new chance to get it perfect. But it always reminds me of golf. Hit a good shot and you’re convinced you’ve figured everything out. Next shot hits your car. All to say, I was excited to begin this stage but I’ve had my fill for the moment.

I found I could not handle more than about 10-12 ounces of epoxy at a time. Mixing in the filler material at that quantity was a beast. So it took a lot of batches to get through all these fillets. I should have kept count but I estimate 23 at least. The pumping also got old and tiresome as it took about 18 pumps for batches that size. Also…I’m using pastry bags from the grocery store and the size I bought wouldn’t have held a larger batch size anyway. So…

To handle larger batches I’m going to try the following:

  1. If I can’t find larger pastry bags I’m going to move to gallon zip locks
  2. To help with the pumping I’m going to break down and buy a metered pump similar to what’s in the CLC shop. Resin and hardener are dispensed at the same time and at larger quantities than the regular dispensing pumps.
  3. I’m going to rig up a mixing apparatus for mixing in filler material. I’ll use an old drill with a homemade paddle as described on the CLC site.
  4. I’m also trying to figure out a spigot for my 5 gallon epoxy containers for pouring large quantities of epoxy at a time without having to lift the containers and pour by hand.


Sand the hull and all these fillets in anticipation of fiberglass…

2 replies on “Floors & Bulkheads, Pt.4 – Fillets”

Hello Before you buy a metering pump try weighing out epoxy. I use a digital kitchen scale. It works great and you can mix any quantity. Even very small accurately. MAS has an extensive epoxy calculator write up on their website which can help with estimating how much you need for a project. They have a mixing calculator that can tell you volume or weight. The simple answer for penetrating epoxy is 100:43 resin to hardener ratio by weight.

Thanks Tom. I’ve heard several people say similar things about measuring by weight and it does seem to me it’s likely the most accurate method. I purchased a metering pump back in August and am completely sold on it. From a convenience standpoint it’d be hard to beat. Now, as far as accuracy…I did a ratio test with measuring cups and it’s on the money, but I can imagine I need to stay diligent about cleaning it out every now and then and also spot-checking the ratio. If you’re measuring by weight you’ve got it dead-on every time. No free lunch is there?

Thanks for checking out the blog and the comment!

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