The canoes were typically made out of planks split from redwood (Sequoioideae) or pine driftwood washed up on the shore. This driftwood was usually chosen because it was available and usually knot free and easy to work with. Some of these driftwood logs were selected, cut to length, split, shaped and then their split out planks ""sewn"" together to form a canoe. The side planks and canoe bottom were split out of straight knot free logs utilizing whalebone and antler Wedges driven by rock mallets. The planks were then shaped, trimmed and leveled using flint and seashell tools and shark hide sandpaper. Where planks needed to be connected holes were bored in the planks using wood drills tipped with chert or bone. These drilled planks were then connected by ""sewing"" split and shaped knot free planks together on their ends to get the necessary length. They were typically fastened together with red milkweed (tok) fiber cords. After the planks had been shaped and sewn together for length they were carefully shaped, bent and mounted six to eight planks vertically to form the canoe's sides around a large split bottom plank that formed the bottom of the canoe. Over 20 pieces of shaped wood are used to make a typical tomol. Once the planks were bent, fitted and lashed together the heart of dry tule rush was forced into the cracks between the planks on the outside of the canoe hull to act as caulking. All seams between planks, plank ends and holes for cords or thongs were then caulked with 'yop', a mixture of hard tar and pine pitch melted and then boiled. In many respects their boat construction technique mirrored that utilized for making small wooden boats around the world. The lack of metal tools and fasteners forced them to use Stone Age tools and materials.