In a salmon skin post the idea of sewing waterproof seams came up for me, and I’m wondering if anyone knows how to make them for kayaks, boots, and the like.
I do know one stitch called the ladder stitch or butt stitch. It is used in making turn shoes and likely other shoes. Below is a “stitchdown” turnshoe that I made. The leather is thick buffalo hide that is so thick (8 oz) that I could sew through the flesh side into the edge of the leather, to another edge and up through the flesh side. This could be called “subcutaneous” sewing as the thread doesn’t show up on the surface of the shoe.
You can see how I sewed it in this picture below: 
I’m wondering if this is a method used for sewing kayaks. These shoes are definitely not waterproof due to the chrome tanned leather not being waterproof (theoretically I could put nikwax or something to make them waterproof). But I could see oil tanned skins, like I assume Alaska natives and Inuits used for kayaks, would become water proof with good sewing and some epoxy in the seams.
To make the subcutaneous holes to sew in I used this curved awl. 
