It will be noted that all Eskimo skin boats have a complete framing system, which is first erected and then fitted with the skin cover. This is a method of construction very different from that of the birch-bark canoes of the Indians living to the southward of the American Eskimo. The birch-bark canoe is built by forcing a framing system into an assembled cover and holding it in place there by a rigid gunwale structure, to which the bark cover is lashed. This basic structure is used even in the Alaskan area, where there are birch-bark canoes that in hull form and proportions strongly resemble the flat-bottom kayak. The basic difference between the two craft is illustrated by the fact that whereas the removal of the skin cover of the kayak leaves the frame intact, the removal of the bark cover of the kayak-like birch-bark canoes would result in the collapse of the framework, except for the gunwale-thwart structure or, in a few, the chine-floor structure. Because of this basic difference the superficial resemblance of some Indian bark canoes to kayaks has no meaningful relationship to the possibility of the influence of the kayak on the bark canoe, or vice-versa. Some Indian tribes have in fact built skin-covered canoes, as will be seen in chapter 8, but the framework and structural system used is always that of the bark canoe, never that of the Eskimo skin boat. Nor is there evidence that the Eskimo ever used the bark canoe frame-structure in their kayaks or umiaks. Hence, in spite of contact between these peoples, the watercraft of each remains basically different in structural design. The almost universal method of constructing the kayak is first to shape and fasten together the gunwales and thwarts, with stem and stern pieces fitted as required, then to fit and place a few transverse frames to control the shape of the craft. Next the longitudinals are fitted and, finally, the remaining transverse frames are put in place. In some types the manhole rim is now fitted but in others the manhole rim is put on after the skin cover is in place, as some kayaks (the Alaskan) have the skin cover placed over the manhole rim and others have it passed under. The skin cover is stretched and sewn over the frame and is rarely secured to it by lashings except at the manhole. Due to the shape of bow and stern, in some types, difficult and tedious sewing is required to stretch the skins over the ends of the hull. Much of the sewing is completed after the skins are stretched over the hull and held by temporary lacings. The blind seam is used but in many kayaks the lap is very short, about ⅜ inch being common.