: I'm about to re-skin my
: old kayak, and would like to use a single piece of canvas rather than
: covering the hull, then the deck. It's a twelve-footer with a 24 inch
: beam. Has anyone done this, with a single seam down the center?

This method for covering a kayak is pretty common. You'll see it used a lot on baidarkas, and on kayaks that are made from stringers lashed to closed-cirle, or oval ribs.

Kayaks that have well defined lines that separate the deck from the the hull at the sheer chine, or gunwale will usually have a continuous chine, running from one end to the other, into which you can staple. Boats of this design, and that includes Putz's Walrus, can be skinned in two parts, with the parts being joined along the gunwale. The skin may be secured with staples or copper tacks.
This method has some advantages in that different materials may be used for the deck (something breatheable) and for the hull (something tough like a auto tire).

With Putz's walrus the hull is built first, then curved supports for the deck are attached to it. Essentially this is a canoe with thwarts that are shaped like bridges. With other kayak designs the "ribs" or frames are roughly horizontal ovals in shape. The bottom part of the oval defines the shape of the hull, while the upper part of the oval defines the dhape of the deck. With this construction each rib or frame does double duty, and there are no separate deck supports. These frames are held together by -- and at the same time provide support for -- the longitudinal chines which define the shape of the boat. It is possible that some of these chines might be above water and could provide an attachment place for a skin to be tacked on.

If there is no chi8ne that can be used for stapling or tacking on the skin, then you are stuck with doing exactly what you originallly proposed: making the cover in one piece, and lacing it up, fore and aft.

You can sew such a cover into place with a needle and thread, or, you can loosely fit the fabric, and mark it for eyelets, which you can insert with the appropriate tool. Once you have eyelets in the fabric you use a heavier cord (not thread) or something about the size and strength of a shoelace. This allows you to remove the cover periodically to clean or dry it, or to store it, or to patch it. It also allows you to tighten the skin should it stretch.

This type of laced on skin is very useful if you are thinking of building a "folding" or collapsible kayak. You unlace the skin, remove the chines from the ribs, and put the thing away. For even easier storage you make chines in two or three shorter pieces, with ferrules for joining them.

If you are lacing up the skin, allow extra fabric along the seam. Roll and fold this fabric tightly and it will keep out water, then lace the skin so the rolled fabric is trapped between the laces and the deck supports.

Fitting the cockpit and coaming is a bit of a problem. If you plan to remove the skin, you might want to NOT attach the coaming permanently to the boat with glue, but simply let it rest in place while you skin the thing. Attach the skin to the coaming. You can then use bolts and wingnuts to hold the coaming to the cockpit.

Hope this helps.

PGJ