Not the only way, but the way we've done it that works. An important word: what you find here is an IMCOMPLETE record of the process, created for a student who was unable to complete his boat at school. As time goes on, I may fill in steps, but this is by no means a full set of directions. When it comes out soon, I recommend the book Building Skin-on-Frame, Double-Paddle Canoes by Hilary Russell,of Sheffield, MA.

Order of Operations

  • Creating the Stem-Knee assembly
  • Attaching Knee to Keelson
  • Fill four spaces in gunwale for thwart attachment
  • Sand gunwales and breasthooks
  • Attach thwarts
  • Fit, drill gunwale rub rails
  • Assemble floorboards
  • Shape nose and tail for brass rub rails
  • Coat all wooden parts with oil or varnish: frame, rubs and floorboards
  • Skin the boat
  • Shrink the skin
  • Skin coating
  • Attach all rubrails, wooden and metal
  • Last odds and ends

Notes on related subjects

5.23.2010

Odds and Endings

In no particular order:

Grab loops.  A couple short lengths of  7 or 8 mm perlon (climbers cord) make nice grab or hanging loops at each end.  Make a loop, tie the two free ends together with an overhand knot, and shove the loop through the hole in the breast hook from inside, so the knot catches under the breast hook.


Seat cushion:  in the past I've used some of the leftover canvas to cover the chunk of seat foam.  This year I tried using some of the fabric dye to color the cushions - not a good idea, as it turned out;  the dye ran when Matt and Peter tested their boat, so I had to remove the covers and wash them in hot water to resolve that problem.  Hence the pinkish faded color in this photo.








Maker's mark:  The little bronze tag that says Sarum Boats.  Easy.  Drop into the shallow hole and pin with two tiny brass brads.











Paddle note:  While a skilled paddler, can pilot this boat with a single bladed canoe paddle, using the 'J-stroke', the boat is a joy to paddle with an extra long double bladed kayak paddle.  There are some links to manufacturers on the Sarumboat blog.  A little research on the Internet will also yield sources of plans for building your own, if you wanted to try that.  This paddle will seem unusually long, compared to what you might find at the average EMS.  Mine is 260 cm (102 inches).  We made some here at school which are about 8' 4"  (by the way, rubber drip rings are a good idea for your paddle shaft - they prevent some of the water picked up by the blades from running into the boat.)


Rubs

Reattaching the wooden rub rails aver the staples is easy - just screw them back in.  I recommend doing it by hand (tedious, but a good wrist workout) or using a drill with adjustable torque settings, set so that the clutch slips before you can crank the screw too hard.

















The bronze stem bands are a bit trickier.  Start with the boat upright, and place the bronze 1/2 round on the breast hook and in contact with the stem.  Drill pilot holes for the first two screws.  The screw pack has enough longer screws for two at each end of the boat. Use the short ones everywhere else. Once the band is attached with the first two screws, turn the boat bottom side up and proceed.


Screw pack.












Start by anchoring the rubstrip on the breasthook.



Last screw on the underside of the boat.















The bronze 'rub' or stem band tends to bend more easily and sharply where the holes are drilled, so place the screws one at a time: drilling, screwing, aligning and bending as you go.  Run a narrow (1/4") bead of silicone down the keel stringer where the stem band will lay, to seal the screw holes and the staple seam (though this may be redundant, given the properties of the polyurethane).  When the band is screwed down, wipe and excess squeeze-out of silicone off with a rag.  Vinegar works well to clean up smears on the skin.

5.15.2010

Coating the Skin

The material we have been using for the past two years to coat the skin of the boats is a two-part polyurethane that we purchase from the Skinboat Store, in Anacortes, Wa. This is mixed one part A to two parts B and stirred THOROUGHLY. It needs to be well mixed to set properly, and believe me, to be left with a sticky, uncured mess on your boat skin would be a disaster of the first magnitude. On kayaks, the best way to apply this is with a scraper/squeegee, but with the additional stringers and multiple lashings making small bumps on our skins, the best way is with a disposable foam brush. Three coats can be put on a few hours apart, though in our school setting we have done coats on successive days, and it has worked just fine.

In the photo below, an acid dye (also from the Skinboat Store) called Russet (they carry 8-9 colors) has been used to color the canvas at the same time we shrink it. If you use just the polyurethane with no dye, the color will be a pale, yellowish transparent film, almost like skin of some sort.  To shrink the skin with no dye, just put the boat out in the hot sun, and hose it down with cold water.  Then let it dry.  If using the dye, but the dye in a spray bottle, and with a rag in one hand and the sprayer in the other spray evenly and then wipe to prevent runs. Once the entire boat is done, let it dry in the sun.





A perfectly good alternative is water based polyurethane from the hardware store. It dries fast; you can put on a coat every few hours, and build up to 5 coats quickly. For an opaque, color coat, mix ¼- ⅓ artists’ acrylic gesso and some acrylic paint of your choosing with the polyurethane for the first couple coats. Brush it as evenly as possible to avoid brush marks. Finish with 3 more coats of poly.

5.06.2010

Skinning the boats














We've given the Waterlox Marine several days to dry.  If we were using water based polyurethane, this would not have been necessary.

Start by laying out the nylon canvas over the inverted boat frame.  Make sure it hangs far enough over each end so you won't come up short when you stretch the canvas over the stems.














The first staples go in in the center of the boat, in the center of the gunwale, running parallel to the line of the gunwale.




Put in five or six on each side, starting in the middle.  After doing the first side, go to the other side, and while pulling the fabric as tight as you can, staple the opposite side.  Now, work your way toward the ends, first one way, then the other, alternating sides;  put in a few staples, then go to the other side, pull the fabric as tight as you can, before stapling.  This can be tricky - you need to accomplish three things with two hands: pull the fabric taut, back up the gunwale with the same hand, and staple with your dominant hand.  If the staples don't go quite all the way in, you can tap them flush with a hammer.  If they go seriously askew, pull them and try again.















As you work toward the ends, you should be pulling not only straight down, bu diagonally towards the ends.  You should try to pull tight enough that all the big wrinkles begin to smooth out.  (small folds from the fabric being stored folded will go away when you shrink the fabric.














When you get close to the ends, instead of stretching between the gunwales, you'll be stretching the fabric between the keel and the gunwale on each side, to cover the 'triangle' on each side.  Do one side first, stapling from about the first rib, toward the tip, leaving enough space between the staples to fit a second staple.



Once one side is done, use the hot knife to trim the fabric even with the edge of the stem away from the side you've just done.  If your staples are correctly down the middle of the keel and stem, then there should be a good 1/4 inch of fabric outside of the staples, which is sufficient.


Your cut should end at about the first rib.  Carefull not to cut into the lashing.  You should not have to cut beyond this point. When you pull the second half over, it will just barely reach (see above), but as you get a couple of staples in there should be ample to overlap the cloth and get a second line of staples in.





















Pull the other side across in the other direction - remember, you are now stretching not from gunwale to gunwale, but from keel (and stem) to gunwale. Get the canvas as taut as possible over this triangular end of the boat, and staple a second row of staples, along the same line as the first, but in the space between the first line.

THE SCARY PART: now you have to use the hot knife to cut away the top layer excess, without cutting into the first layer.  You can lay a layer of duct tape, as insurance, over the first layer, right up to the stapes, but even so, the best way to do this is to pull the fabric out straight, away from the boat a pull as you cut, so the just melted and severed nylon will pull free as you move CAREFULLY down the cutting line.







































Finish the ends as neatly as possible, as in the above photo.
Then use a hammer to make sure all the staples are tapped in completely, and cut the remaining fabric off just inside the edge of the gunwale, with the hot knife.













4.24.2010

Gunwale Rubrails


















Start fitting the rub rails by laying them out along the gunwales and clamping them on flush with the tops of the gunwales.  Drill pilot holes for the screws through each rib, plus one in each side of the breasthook.  These should not go all the way through the inwale; rather, they should stop about an eighth of an inch short.  These holes also need to be countersunk enough for the heads of the bronze square-drive screws to be flush or just below the surface of the rub rails.




















Trim the rub rails even with the ends of the gunwale and stem.  Then, remove the rubrails from the boat and round the outer two edges.  Do NOT round the edges that will be against the canvas.  The outer rounding is so when you bump your hand on the rubrail while paddling - and you will, occasionally - it will be soft and more comfortable.

At this point the rub rails are ready to be oiled or varnished.  Both sides, 2-3 coats.