Alternative coaming - question on rim width


I'm finishing up a Wood Duck 12 from plans and I have a question for all you strip builders out there about the coaming (I already made a Shearwater 14 from a kit so I know the recommended drill for stitch and glue coamings). 

Since I didn't have a spare sheet of 18 mm plywood around to make the coaming risers, but I did have a pile of bead and cove cedar strips, I decided to use the old vertical-cedar-strip-plan for the coaming riser plan, with a slight modification.  I cut the strips 3/4 inch long and hot glued them on the top of the deck (instead of onto the inside edge of the deck like most builds I've seen online).  I also used Titebond between the strips.  Looks good, feels sturdy, and was kind of fun - like a jig saw puzzle, but it didn't matter where you put the pieces, they all fit! 

Here's my question.  The cedar strips are not very thick, so the coaming riser is only 1/4 inch thick (and 3/4 inch high).  I was originally going to do two rows of vertical cedar strips (one outside the other) to make the total riser thickness 1/2 inch, more like the thickness of the pieces of plywood that are stacked to make a "normal" stitch and glue riser.  I have already cut out the coaming rim from Okume, and it's about 1-1/2 inch wide so I didn't think it would work very well if I put something that wide on top of the single-walled 1/4 inch thick riser (too much leverage on the outside edge).  However, I know that most cedar strip boats that use the vertical strip riser method only use one thickness, and then have a much thinner coaming rim.  I'm thinking I could either:

1.  Cut existing coaming rim to "x" width (what should "x" be - 1 inch?  3/4 inch?  It really only needs to be thick enough to hold a spray skirt on right?)

2.  Put on my planned extra row of vertical strips and use the existing width coaming rim.

I am planning to fillet the outside strip-deck joint on the vertical strips and put a layer of fiberglass both inside and outside the strips so I don't think it will be a strength issue if I leave just a single row of strips. My concern with the double row is how to make sure the two rows are glued together enough so they will be structurally sound since there would be fiberglass on only one side of each row.  Would it be best to use thickened epoxy to install the second row to make it a good bond if I go this route?  Will the two-row idea add a lot of weight?  Do I need it? 

Any thoughts from someone who's done this type of coaming? 

I'm leaning toward the single row, trim the existing coaming rim narrower idea at the moment, but wanted to see others' opinions before I do any cutting. 


13 replies:

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RE: Alternative coaming - question on rim width

Hi Kathy,

If you do go the double-wall route, definitely use thickened epoxy unless you can make a perfect fit between the layers. Titebond does not like gaps, it needs the air excluded to set up properly. Thickened epoxy will happily fill the gap.

I haven't done exactly what you're doing, but my gut feel is that one row should be enough if you build it as you describe it. Since the cedar strips will be oriented so that the grain runs vertically, the riser assembly will be very strong in compression, especially seated on top of the deck. The main stresses will be torsional - trying to twist in or out. But gluing the individual pieces to each other and the deck, as well as binding them with a layer of glass, not to mention the fillets, should pretty well immobilize them.

Keep in mind that it's a good idea to have a fillet between the riser and the rim, too, (which will easily eat up another 1/4" or more of rim width) so don't trim it too narrow. I like to use the whole rim width, apply all the fillets and stuff, then sand the rim to its final size.

Sounds like a fun mini-project,




RE: Alternative coaming - question on rim width

Hi Laszlo,

Yes, my concerns on strength were mainly twisting, pushing on the outside of the coaming rim, and using the coaming as a handle to carry the boat.  I've looked at quite a few cedar strip builds that use a single vertical strip for the coaming wall, and they all seem to hold up.  I was planning to do a fillet on the outside wall-deck joint as well as the outside wall-underside of the rim joint and apply fiberglass on both the outside and inside that will wrap down onto/under the deck so I'm hoping it will be strong enough. 

I will wait to trim the rim until I have it installed, that way I can also get it even all the way around (assuming I can cut to the line I draw!) since things never quite line up perfectly on the coaming I've found. 

I'll probably put some veneer on the top of the rim also; I couldn't get Sapele plywood for a reasonable price out here on the West Coast when I started this project, for some reason everyone was out of it, so I ended up putting a swirl of bubinga veneer along the deck.  Having never done veneering before it took me several months to work up the courage to potentially mess it up, but it turned out OK and I'm thinking some bubinga on the coaming might bring it all together. 


RE: Alternative coaming - question on rim width

Would love to see some pics, especially since you do such fine work Kathy.


RE: Alternative coaming - question on rim width

Hi Hickory, I'm going to try to post a photo just after the veneer was applied, but I've never been successful at posting a photo on this site before despite trying to follow the instructions. 

veneer applied

If the image above doesn't show up (I'm not seeing it so I suspect it won't), you can try this link:

Let me know if that works or not. 

On the photo, you'll see some clear packing tape on the hatch cover because I have already installed the rare earth magnets, but no handle yet, so I needed some way to get the cover back off! I needed to put the hatch cover in place to get the veneer lined up.  I used the iron-on veneer process and I installed the veneer onto the boat without the hatch cover on, then cut out the piece that would go on the hatch cover, then put the cover in place and ironed the piece onto the cover.  The veneering was fun, but not without pitfalls of course. Every time you do something new you learn what you will do differently next time you do it. 

I'll post photos (or at least a link) to the alternate coaming process when it's done if you're interested. 


RE: Alternative coaming - question on rim width

That link to the picasa photo worked just fine.  Beautiful veneer.  Looks like the pattern follows your carpet!

Love to see your pics and hear your thought process on your work- learn lots.

After seeing you shearwater build log, I've decided my second build will be a shearwater sport w/ strip deck.




RE: Alternative coaming - question on rim width

Hickory, your wherry looks great (saw photos on your post).  Working with the cedar strips on the cockpit coaming was lots of fun - hopefully some day I'll get to build a cedar strip kayak - but have to finish this one, and then see if my husband will let me build a third boat (I kind of doubt it, but there's always hope). 

RE: Alternative coaming - question on rim width

Kathy's boat pic.

Nice veneer job, great effect,


RE: Alternative coaming - question on rim width

Here's a pic of the coaming rim and riser on the Auk14. It's all 1/4" cedar. I ripped some strips are skinny as I could so I could bend them without steaming.

I built up the riser, wrapped tape around it then glued the laminations together. I then removed the rim, sanded the top and bottom and glued it on to the riser

RE: Alternative coaming - question on rim width

I used the alternate method 1 from my original post to install the coaming, and I think it worked out pretty well. 

I put 1 layer of vertical cedar strips (3/4 inch high) on the top of the deck to form the coaming riser.  I used hot glue to attach to deck and wood glue between strips.  Then I installed the full width coaming rim on top using thickened epoxy, at the same time putting a fillet between the outside deck/coaming riser and riser/underside of rim.  While the fillets were still wet, I painted the entire outside coaming area with resin and applied a strip of bias-cut 4 oz. fiberglass tape that spanned the deck (about 1 inch on deck), riser, and underside of coaming rim.  Smoothed everything with gloved fingers.  This wasn't the easiest thing to reach, but I wasn't sure how else to do it.  Worked out OK in the end.  

After that all cured, I trimmed the outside of coaming rim so the total rim was about 1 inch wide, sanded everything smooth (applied bubinga veneer to top - another process) and then used more bias-cut fiberglass tape to cover over top of rim to inside of riser to underneath the deck. The end result is a covering of fiberglass on both inside and outside of deck/riser/rim. 

It's quite stiff and I think will be strong enough.  You can see photo progression here, near the end of this photo journal:

I think if you click on each photo you will be able to see the caption/explanation (hopefully the link works). 

This may not be the best or easiest way to go, but it worked for the materials I had on hand (cedar strips but not 9 mm plywood) and I think it turned out fairly nice looking.  Installing the cedar strips was actually kind of fun, quick, and quite easy.  Getting the fillet under the coaming riser wasn't.  The rest was pretty staightforward. 


RE: Alternative coaming - question on rim width

Drilling all those perforations to get the outer strip of the coaming off must've been tedious. Sound like the inspiration for a new song  - "1000 Tiny Holes in the Boat" (to the tune of "100 Bottles of Beer on the Wall"). But it worked really well and I don't see that you had much choice for getting that strip off without damaging the deck. Better you than me :-)

Looks really nice and it looks as if you're getting close to launch time. That veneer job's going to get a lot of comments.

Have fun,



RE: Alternative coaming - question on rim width

Great photo log, with all of your descriptions.  Very helpful for other builders.  Outstanding workmanship (workwomenship?)!


RE: Alternative coaming - question on rim width

The bubinga veneer looks amazing!  That is a great looking boat.


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