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SOF Build


Nov 24, 2007
Nanaimo, BC
I’m looking to build a SOF boat this spring and am just in the beginning planning stage. I’ve never built a boat of any kind before so it’s going to be an interesting learning curve as I go through the process. There are enough cedar mills in my area (Maple Ridge, BC) that sourcing out frame material will not be a problem but my first question has to do with skin material. Is ballistic nylon the best choice or are there other materials you would recommend instead? If the nylon is a good choice, does anyone know of a local outfit I can purchase it from?
Thanks for the help,
hi Doug;
i'd suggest that you pick up a copy of Robert Morris' book, Building SOF Boats. it's a great place to start.

George Dyson, in Bellingham, is by far the ONLY place to buy skinning material from. anyone that might have it locally will have gotten it from George. he carries both Ballistic Nylon and Polyester fabrics. all the SOF boats that i have built have been covered in BN. after the first one, in 12ounce, i went to 8ounce material. 12 was overkill for my usage. i'll be happy to answer any questions you might have, but i suggest you check out the Greenland forums. many of the builders there have been using the polyester cloth and some say they like it better than nylon.

There's also www.skinboats.org ,in Anacortes, they carry three or four weights of nylon, depending on your usage. I've been buying texturized nylon from fabricmasters, in North Carolina, by far the cheapest source of nylon, but don't always have stock of the weights I'm looking for, so I sometimes have to wait on them, so when I do order, I buy enough to do several kayaks.
If you do use polyester, your sewing has to be spot on, because you won't be able to shrink out any looseness.
There's also vinyl coated polyester, i.e. shelter-rite, which is applied with staples and glue (hh66), and requires no sewing or coating, that works out to about the same weight as fully coated nylon.
The fourth possibility is aircraft dacron, which allows for the greatest amount of shrinkage, and a very light skin, but seems way too fragile for my preferences.
I'd also suggest taking a peek at www.yostwerks.com Tom Yost is a designer of sof boats in a non- traditional style, I think he started with folding kayak designs, and has expanded to cover non folding wood frames as well.
Thanks Daren,
I’ve got Chris Cunningham’s book but I’ll go and get the one by Robert Morris also. I’d also bought Harvey Golden’s book to use mainly as a reference source but found it to be really interesting as a read all on its own. I’ll take a look at the Greenland forums also before making a decision on the skin material. I’m sure to have lots of questions for you as I get started on this boat so I appreciate the offer.
I owned that 12oz covered boat that Daren built for a few years and really put it through it's paces. I'd recommend the 12oz if you're looking for a boat with some durability.

There are enough cedar mills in my area (Maple Ridge, BC) that sourcing out frame material will not be a problem

Do you know enough about any of them to make recommendations? Say clear wr cedar for our 16'-18' boats? and yellow for the SOF's?
Hi Mick,
I don’t know enough about them to recommend any one in particular.
While trying to locate a copy of Robert Morris’ book, (none available at local bookstores or kayak stores), I was able to get hold of Robert through his website. He said the book was out of print but he had a few copies of his own left, and he very kindly met me in PoCo this afternoon to get me one. (if you are reading this Robert, thanks again) He also recommended Sunbury Cedar in Delta as an excellent source for the wood so I will be heading out there in the next few days.
Quick question to do with the gunwale braces.
Haven't cut apart the gunwales yet but am making up the braces. In RM's book (p. 69/70) he says to cut the forward and aft spreaders 3" and 4" shorter than the mid brace. In the diagram he shows cutting 3" and 4" off each end, for a total of 6 and 8".
Could anyone help with which are the proper dimensions?

the illustration is correct. 3"and 4" off either side, for a total of 6" and 8".

Nylon tends to shrink and expand with temp and humidity, but this tendency lessens with time, with shrinkage being the end result. I think it's actually kind of kool watching the skin loosen slightly, and seeing the deck "breath" with the swell. Reminds me of a lizard or dragon breathing. I've bounced my sof's off things that would make a 'glass kayak shatter, with no ill results.
Finally got back to the build this month.

A lot of time being spent making up jigs and just figuring the whole process out but it seems to be coming along OK. Looking back on it the dumbest mistake I made (so far) was the very first measurement, the length of the gunwales. I ended up making them six inches longer than they should be and didn’t realize it until it was too late to do anything about it. Live and learn. The second boat, I think my wife will want one, should go a lot quicker and smoother.

Made the gunwales out of one piece of cedar, to be cut apart later. After laying out the rib and deck beam locations I made a jig for the router to cut the rib mortises. The jig is adjustable to account for slight differences in the thickness of gunwale stock in the future but will always position the center of the mortise 3/8” from the edge. 26 pairs of rib mortises in all.



Shaping the top edges of the gunwales and cutting the triangles off the bow and stern bottom edges.



Sawing apart the two gunwales. Didn’t want to try this on the table saw as there was only 1/16” of room for error on either side of the saw blade and I figured trying to run a 17’ stick through was only asking for trouble. Took about two hours to separate by hand.


Next was to make the deck beam mortises. Another jig to be made here to guide the drill to take out most of the material. Then used a block with the face cut at 17 degrees and a couple dowels to position it, to act as a guide for the chisel to clean the mortises up. 11 pairs of beam mortises in all.




Bevelling the top edges of the gunwales. Used a sureform to remove most of the material and then cleaned it up with a spokeshave.

Bevelling the gunwale tips. Best part of this step was getting the gunwales in the forms and seeing the shape of the boat start to come together.


Thanks Iwannapaddle. It’s been a fun project so far. I’m enjoying working through the processes using hand tools more than power tools.

Next was to machine the straight deck beam stock to size and start laying out the tenons. The small jig used to transfer the gunwale widths and angles worked really well.




Before separating the gunwales I also roughed out the arched deck beams and laid out the tenons on them.


Next was the pile of tenons to cut. Really had to pay attention so the cut was made on the right side of the pencil line. I did have two tenons that ended up too thin and I wound up gluing shims on those and recut them to size again. Each tenon took about 15 minutes to cut and fit in its mortise, maybe a little longer if a lot of fine tuning was needed.



All tenons cut and fit to mortises.

Next was to shape the arched deck beams. Just ended up taking a spokeshave to the corners and then rounding everything over.



Then finally got to assemble the gunwales and beams. Everything seems to fit reasonably well but will wait until Sunday to see how true it is and hopefully start pinning and lashing it together. Off for a paddle up Pitt Lake tomorrow.



Is that Alaska yellow cedar you are using? The photos may be deceiving me, but it looks to be pretty wide grained and lighter than what I have seen in AYC. Did you get it from that mill in Delta?

You certainly do beautifully precise work. The major longitudinal frame members seem to be made of what, inch thick material? Is that a thicker than usual dimension for a SOF made from AYC?

Keep in sending photos. I know people are loving them.
Good Job, Doug!!
beautiful work!

R.Morris reccomends AYC, and the two gunwales to be ripped from a single board measuring 1 1/2 x 2 3/4. this would yeild two pieces slightly less (by half the sawblade kerf) than 3/4 thick.
scantlings from my own builds, with WRC, read gunwale dimensions of 3/4 x 2 1/2.

Astoriadave said:

That seems like pretty herky stuff. Is that dimension common for SOF's?

i always thought that Morris was over-building his kayaks. probably for the safety factor since he was publishing info for the retail market. CYA; right?
i'm a big fan of DIY, so i used what i had for my first SOF. that just happenned to be 3/4 thick WRC, and it worked just fine. i believe that Mike Jackson has that boat now. it's almost ten years old.