scarf joint

[pgk]

I am building the gunwales for the Townsend 16 and I am trying to scarf two pieces of ash together. Can anyone give me a little tutorial about doing this (hopefully I can use a hand plane).

Sincerely,
Paul

[skiabq]

Rick has a good picture somewhere of the scarf joints on his Issaquah. If you can't find it I can take a picture of the scarf joints on the rubrails on one of my canoes. A picture really helps a lot. I think the formula is something like 2 inches of scarf for every 1/4 inch of thickness. My rubrails have a 6 inch scarf in them and my 1/4 inch hull has a 2 inch scarf in it. I find it easier to use a belt sender for the hull scarfs and a disk sander for nice clean scarfs on the rub rail.

The quick and dirty description of how I do it is to draw a pencil line with a square of where the scarf will end, then I sand to it. I sand a little then check to make sure I am still square, then sand a little more, repeat this until you are done. Try to keep it as straight and square as you can.

Have fun, and let me know if you can't find that picture.

[hairymick]

Hi PGK,

I agree with skiabq, a 1 to 8 ratio is very good, 1 to 10 or 12 is better but not really necessary.

Another way to cut a very good matching skarf is to use a table saw. Cut a piece of wood to the desired angle, screw it to the sliding rip fence then cut as many perfectly matching scarfs as you want. If a wood shop is nearby - it might be worth asking them to do it for you.

Hand planes are good but you need to have some serious hand eye coordination and a lot of care.

[jem]

I did some gunwale scarfs and they pretty much are horrible.

Friend of mine sent me a description of how to set up a jig to cut them with a hand saw. I'll see if I can dig it up and maybe add a sketch.

[pgk]

I made the scarf joints today. I was about to use the sanding method that was suggested yesterday, but I asked another boatbuilder in the area and he told me how to do it with a hand plane. I staggered my two pieces of ash. One on top of the other and a foot back then I marked my angle and went at it.

I must say they turned out really nice. (I think I am pretty well hooked on this boatbuilding thing!) My next dilemma is going to be making the slotted inwale. Can anyone tell me how big to make the slots? Also, when I put in the thwarts, do I glue them to the inwale or to the hull directly? And my final question, where do I put the seats? I assume this is up to me but any general advice is good to hear. Thanks everyone for your thourough and awesome responses.
Paul.

[hairymick]

Hi PGK,

real glad your scarf joints worked out mate.

My slotted inwhales are pretty much a copy of what Matt and Chuck (Old Sparky) do.

I cut a heap of pine strips, the width of my inwhales and about 5/16 thick X 4 inches long. I glued them to the inside of the boat at 4 inch spaces.
When that had set, I glued and screwed the inwhale through all of that on top of the strips..

[Kayak Jack]

PGK, (BTW, WTH does that stand for?), here's what I did for slotted gunnels on a plywood S&G canoe.

First off, trace a pattern of what the inwale will be. It will have a gentle curve in it. Mine is wider near the center of the boat (about 3") and narrows down to about 1 1/2" at the ends. Strength is important in the mid-section of a hull. My hull and inwale are both 1/8" mahogany plywood.

Spacers are from a piece of 1" X 2" pine. Next time, I'd get something only 1/2" thick; the nominal 1" (actual 7/8") is too thick. Then, I cut a basket full of triangles from the 1X2 slat. Cut these as 45-45-90 degree triangles. This way, you can make a continuous zig-zag line down your slat, all lines being at 45 degrees. No wasted material.

Next, I drilled a large hole in the center of each triangle; this lightens it. If the hole breaks through the side of a triangle, scrap it. Then I sanded each triangle. Get the corners smooth, I quit sanding too quick and mine aren't as smooth as they should be.

I held the inwale in place and held it temporarily with C clamps. I drew a line or ran some masking tape to mark the line of the lower edge. After removing the inwale, I began to glue triangles in place along the inside edge of my hull. "Hang" the boat up on its side to facilitate this step. I alternated them with the 90 degree corner pointing up & down, and offset them rather than putting one directly above the other. Little pencil lines help here. As you're gluing them onto the boat, give all triangles a coat of epoxy inside & out.

After all triangles are in place, then glue on the inwale. If your plywood is too short to do it all in one piece, do it in three. Don't want a seam at the center of the hull; again, strength is important here. Have the mid-piece as long as you can get it, then butt your end pieces up to it.

What you're forming here is a thing called a "box beam". It is tremendously strong. You can easily lash gear into place by zig zagging a rope back and forth across the boat over the gear. These light weight ropes make nice guy lines or clothes lines in camp.

[banoe]

Hi pgk

On my Townsend I used 1/4"X3" spacers 3" apart with 3/4"X3/4" inwales and outwhales. I put the glue on them and shot them on with 18ga.X1/2" brads no clamping required. I radised the rails with 5/16" router bit and sanded smooth. The seats I hung from the inwhales with 3" stainless steel wood screws in wood spacer blocks. I used the webbed seats Matt sells and I like them a lot. I can send you pictures and dimensions for seat placement if you like.