Coaming and spacer thickness on Shearwater Hybrid

I am building a SW Hybrid from plans, therfore cutting all the wood from my own supplied Okoume plywood. The assembly manual says to use 4mm Okomue plywood for all the parts but when I rolled out the pattern prints a little discrepency set in. It states "COAMING SPACER 9MM OKOMUE - MAKE 4." I am confused as to how you could add the spacers up to equal 9mm or even where that figure came from. Am I missing something?

It also shows the coaming cut from 3mm Sapele. I don't have any Sapele and 3mm seems awfully thin. I do have a supply of Okoume plywood in 3mm, 4mm and five ply 6mm. My thoughts are to cut the coaming spacers out of 4mm and 6mm and the coaming out of 6mm. This would give the spacer height of 10mm with a 6mm coaming. Thoughts on this matter?

Mt next question would be what is the best thickness for the cockpit apron? Should I cut it from 4mm or the thicker 6mm? The 6mm is almost 1/4" or about the same as the cedar strips. 


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RE: Coaming and spacer thickness on Shearwater Hybrid

Since you're strip building the deck, how about skipping the plywood for the coaming too?

Nick Schade's ply-less coaming how-to video:

Of the 8 or so ply kayaks I've helped others build in my shop, the cockpit material tally is about 5 in carbon, 2 from strips a la Schade, and just one with stacked ply per the manual. It's my least favorite- but you should build what suits you!

RE: Coaming and spacer thickness on Shearwater Hybrid

nemochad, I watched Nick's video and do like idea of the cedar riser and combing though it does look like a lot more work though. I think the plywood looks a little out of place on the stripped deck.

One thing of note from the video, he spaces the combing 3/4" above the deck.

RE: Coaming and spacer thickness on Shearwater Hybrid

A littl more work, but of a much more interesting kind. Cutting 1/2" wide curved strips of plywood over and over, then sanding all that edge grain after it's glued up, is just irksome work in my opinion. If they're already cut in a kit by a never-bored or -aggravated cnc, that's fine. But hand cutting them was a drag!

RE: Coaming and spacer thickness on Shearwater Hybrid

When I have cut plywood spacers in the past, I rough cut with a jig saw, stacked them up and finish cut on the band saw then smoothed with a drum sander. 

RE: Coaming and spacer thickness on Shearwater Hybrid

Yep, similar here. Never a fan of cutting thin frail stuff with a jigsaw. 

RE: Coaming and spacer thickness on Shearwater Hybrid

I have been searching through the archives and gathered a little more insight on the spacer question. Where the manual only says the cockpit is a sandwich of four spacers and one coaming ring, it fails to mention they how thick they should be.

I found in an earlier post where John Harris from CLC said the ideal spacing is 14 to 18mm which is in line with Nick Schade saying the combing should be  3/4" above the deck.

With that, I may use two 6mm and one 4mm spacers on each side for a height of 16mm.

RE: Coaming and spacer thickness on Shearwater Hybrid

   Hi Peter,

I finsished that model last year for my daugher ( from a kit ).

If you do not have a solution I can scan some pages in and do some measuring in my garage. The kit did not have any sapelle.


Anthony in Boston 

RE: Coaming and spacer thickness on Shearwater Hybrid

   Hi Anthony, 

I did get an assembly manual with my plans and it shows all the material being cut from 4mm Okomue. It only says that the cockpit is a sandwich of four coaming spacers (two per side) and one coaming ring but does not mention the thickness of the spacers.

I would be interested in finding out how thick the kit spacers are. Were they two 9mm spacers per side? That would bring the bottom of the coaming about 3/4" above the deck where two 4mm would only be 1/3". 

That measurment would be great,


RE: Coaming and spacer thickness on Shearwater Hybrid

Excellent timing for this subject because I am working the cockpit coaming of the Yukon this week.  I have used ply for the spacers/lip on all four of my strip builds.  I agree that cutting the pieces is not the most fun part of the build, but it is quicker than gluing a hundred strips around the opening. 

Size of the lip and spacer thickness is at your discretion.  On my race boats, I go for minimum weight, so I use three spacers cut from 3mm ply.  I would not go with any less thickness for the spacers because just barely leaves enough space for a cockpit cover or skirt to attach.  For recreational use, I’d go with a little more thickness, maybe 3 x 4mm or 4 x 4mm.  I would not cut the spacers from the 9mm because it will be harder to bend into shape.  I also use 3mm for the lip.  It will be plenty strong enough if you glass over the top.  I use Sapelle for my cockpits because I think that it goes nicely with the WRC deck.  I am not sure that I would like the look of Okoume with a strip deck so you might consider a stain.

One trick for gluing the coaming.  Before you start, tape the deck around the cockpit opening with clear tape.  Then, put thickened epoxy between the spacers and clamp into place.  Do not glue them to the deck and don’t glue on the lip.  Once the epoxy cures, you remove spacer assembly to clean up all the epoxy squeeze out.  I find that a belt sander clamped to my work bench works well.  Next, repeat the process when you glue the lip on.  Once you have the completed coaming cleaned to your satisfaction, remove the tape and glue to the deck.  The last trip is to use a bit of wood flour in addition to silica when you thicken the epoxy.  This will color the mixture, so it matches the wood.  With just silica, the mixture is a very visible white color.          

Pictures below:

1.  Glueing lip to the spacers.  Note the clear tape on the deck so that the assembly can be removed for cleaning.

2.  Coaming assembly glued to Yukon and almost readt for fiberglass.

3.  Sapelle coaming on my Mystery

4.  Sapelle coaming on my wife's Frej.


RE: Coaming and spacer thickness on Shearwater Hybrid

   Mark, thanks for the recommendations on the spacers and tips on their glue up with the tape trick. I have read about that on this form and plan on doing it that way. In my past builds I glued right to the deck trying to keep everything in place while clamping down, not an easy trick. 

In the past, I have used two 6mm spacers below the coaming which makes it less than 1/2" above the deck making it difficult to attach a spray skirt. Right now I'm leaning toward two 6mm and a 4mm or three 6mm spacers.

My coaming will have to be made of okoume and staining it would look good only I will have to see if I can sand all the epoxy off before staining.


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