cutting the sectional

I'm making the Shearwater Sport Sectional, and I'm wondering if there's any reason not to make the sectional cuts after glassing and epoxying the entire boat, but before sanding and applying the additional fill coats of epoxy.

My arguments for cutting the boat into thirds earlier than in the instructions are:

1) Less epoxy to saw through.

2) Any mess that I make either sawing, filling the gaps between the bulkhead and deck, or fiberglassing the bulkheads will be easier to cover up earlier in the epoxying process.

3) Based on the discussions here, I'm considering the graphite-epoxy bottom approach, but I do not want to apply graphite in my finished basement which is where I've been working so far (with lots of dropcloths and vacuuming).

But this is my first build, and I may be missing a reason not to do it this way.

While I'm at it, also have a question about filling the gaps between the bulkhead and deck -- what mix should I be using?  Could I use microballoon filler here to reduce the weight?  From looking in through the hatches, I can see that there are some pretty big gaps to fill to ensure water tightness.




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RE: cutting the sectional

   If it were me, I'd want the sections to match at the joints.  Making the cuts and then sanding and placing more epoxy, etc does not make that happen. 


Less epoxy to cut through.......... the truth is there isn't much to begin with. If it is tough........ your saw it too dull. 

RE: cutting the sectional

   The manual says that for the final sanding and varnishing, you reassemble the boat with spacers to prevent the pieces from sticking together -- I was assuming I would do that for the epoxying as well if I cut it earlier.

RE: cutting the sectional

I have build the Shearwater Sectional and I think you approach makes good sense. Don't be surprised if there is some filling and repair to do after making the cuts.

I did everything I could to steady my nerves and plan everything carefully, but even so my handsaw wandered a bit as I sliced the boat apart. I cut into the bulkhead! That meant I had to make a dam, fill the damaged area with epoxy and sand everything smooth. . . . But the great thing about wood boats is that you can fix everything! I love the finished product.

After you cut the boat apart, you'll have a decision to make. The bulkheads will be 1/8 to 1/4 inch below a ridge of surrounding hull. I decided to plane/sand that ridge down until it was flat across the bulkheads, but if your hand was steadier than mine and your cuts turn out bettter, you may not have to do anything more than sand the ridge. Decisions. Decisions.

RE: cutting the sectional


i'm in general agreement with Birch2 that you can change that order of operation and gain some of the advantages you point out without any significant disadvantages.

on filling the gaps, the bulkhead in a sectional is an important structural elements that is under more stress than the bulkhead in a regular build. so for addressing the gaps and filleting, i would stick with a structural epoxy mix of woodflour with some cabosil/colloidal silica (or the white powder) mixed in to make the mixture smoother.

if you have a gap, i typically will duct tape the back side of the gap to keep the fillet material from pouring through.... and ensure i push the fillet materil into the gap (not taped side) and this keeps things very neat when you then pull the tape off after the fillet hardens.

if the gap is so large that the fillet would not cover it (wider than ~ 3/4 inch), you can take some scrap okoume and carve it into the gap and bond it in place with epoxy/cabosil mixture and glass tape over it....then your fillet.....and that should be just fine.


RE: cutting the sectional

   Either way let me know the positives and negatives of switching these steps as I will be right behind you.

RE: cutting the sectional

Popping in to report that I have successfully cut the sections!   I compromised and did it after the second coat of epoxy but before the third.  So far, I'm feeling good about the choice -- I think I can clean up any mess caused by the cutting and fiberglassing of the bulkheads in the prep for the third coat. Will report back after I've applied the third coat.

Cutting the sectional was scary but not too difficult.  The most nervewracking thing was that that the holes on the sheers and the top did not line up with the ones on the bottom and sides -- they were about a quarter inch off.  Not sure how I managed that, but I trusted the ones on the sides and bottom, since they had been nailed into the cardboard, and that turned out to be the right choice.

I used masking tape to mark the cut line all the way around, which worked well and was easier than trying to draw a straight line on a curved surface.

My son helped stabilize the boat for the final cuts -- at his suggestion, we taped across the cuts on the bottom while I cut the top to reduce the possibilty that it would tear the wood on the deck when it got close.  Seemed to help, although I haven't done it without it.





RE: cutting the sectional

 Did the third coat of epoxy over the weekend, and had no issues from the boat being cut.  I used extra plastic scrapers to separate the sections so they wouldn't stick together.  Bottom line is that I think it's fine to cut the boat earlier in the process if it works better for your workflow.

RE: cutting the sectional

I'm also right behind you on this one, so thank you for opening a thread on the topic.

This is actually something that I have given quite a bit of thought to as I'm in a potentially unique position. I cannot move my boat out of it's current basement assembly area until after it's cut into 3 pieces. This is because the stairway landing to the basement has a very tight corner that won't accomodate a 14.5' rigid structure. For the record, this was planned (the basement is the only work space with enough winter heat for epoxy work) and not an accidentail discovery after construction :)

Anyway, I don't want to be doing any sanding of epoxied surfaces until I can get things up into a properly ventilated area, and the offical instructions call for some such sanding before making the sectional cuts. Your plan boost my confidence that I can slightly adjust the order of operations to accomodate my needs... and I also really like the idea of using fill coats to cleanup edges!

RE: cutting the sectional

 I'm also building in a basement that I couldn't get the boat out of until it was cut. (And yes, I also knew what I was getting into.)  But I've been sanding in the basement (wearing a mask with filters). It hasn't been too bad, but I'm definitely planning on taking it to the garage before the varnish stage.

I do think you'll probably want tp sand the sides where the fiberglass drapes down from the deck a bit to get rid of any bumps and ensure good adhesion.

RE: cutting the sectional

   FWIW, I recommend testing the kayak in a pond or lake before you move on to varnishing. It's not uncommon to have a bit of leakage at the joints that must be fixed before the final coats of varnish are applied.

RE: cutting the sectional

I very strongly second Birch2's suggestion. Not only because of possible leaks, but in case you find that any structural work, like changing the size and location of the cockpit, hatches, etc. needs to be done. The last thing you need is to have spent a lot of effort on a high quality finish and then have to remove and redo some or all of it.

A sea trial also lets you establish the waterline in case you're doing anything special for the underwater areas.



RE: cutting the sectional

I did take mine for a float test a few weeks ago, before the temperatures here plummeted.  There was some water coming in, but I think it was from the holes where the bolts come through.  

RE: cutting the sectional

   You are probably right that the leakage comes from those holes, but to seal that up you need to have both bulkheads sanded entirely level so that the rubber membrane gives you a good seal. I'd do all that sanding (and perhaps some filling with epoxy) before you move on to varnishing. Get it water-tight!

RE: cutting the sectional

Birch2, is your suggestion to do some leak tests unique to the Sectional, or is that general advice for all builds? I suppose the joints of the sectional are quite unique, so I'm just trying to get a sense as to how vulnerable they may be.

Lots of good knowledge here!

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