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.

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.

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.

Shaping the Ends of the Boat to Fit the Bronze Rub Rail

One of the very last things to go on the boat is the metal rub-rail which wraps over the breast hook and along the stems onto the keel stringer.  When you bend the piece in a vise, you can't quite get a sharp 90 degree angle, so what we do is round the top of the stem and gunwale to match the curve we do get.  Do this now, before you oil the frame and other parts.  Use the metal part as a guide, and sand by hand to get as close as you can to the required radius, but don't beat yourself up too much if its not perfect.  As long as the arms of the metal piece lay flat on the stem and breast hook, it will be fine.

The installment of this piece will be covered later; for now, I just want you to have shaped the ends before oiling.

Note: when you do this shaping, you can save time later by putting the wooden rub rails on while you do the shaping, so they will match the profile of the bow and stern.  Also round them off nicely on the outside.

This is what you'll need to do if you forget to round the rubrails when you round over the bow and stern.  It seasy enoughn to go back and mark themto match and round off the ends to match the boat.  A little Waterlox touch -up with a small brush will be required.

Floorboards

The floorboards are constructed separately, from strips of ash, 1/4" thick by 1" wide. Actually, you could have a lot of variation in these - 3 wider pieces instead of 5 narrow. Whatever prevents you from sticking a foot or paddle thought the open grid of the boat frame and provides a platform to sit on. We usually place the three cross-pieces (1) under the paddler, (2) near front thwart, and (3) in the middle. Make sure they will fit between the ribs of the boat, so they will lay flat.

The ends are left relatively unsupported so that they can bend up and twist a little to conform to the narrower boat ends. The pieces are rounded on the upper edges for comfort and the tips are rounded off a little - no sharp edges or points.

The pieces are secured to each other by pre-drilling holes and using copper tacks driven through and 'peened' over on back side.  They are glued with waterproof glue at the same time.