Figure 161
Eskimo Woman Splitting Walrus Hide to make umiak cover, St. Lawrence Island, Alaska, 1930. (Photo by Henry B. Collins.)
The fundamental difference between the construction of the curragh and that of the umiak lies in the type of longitudinal strength members and the transverse framing used. The curragh, like the birch-bark canoe, depended entirely upon its gunwales for longitudinal strength, whereas the umiak has a strong keel, or, properly, a keelson since the keel was inside the skin cover. The curragh used longitudinal battens to support the skin cover. The umiak, on the other hand, has in its chine timbers rather strong longitudinal members that give additional strength to the bottom. Its transverse frames, unlike those of the curragh which were continuous from gunwale to gunwale, are in three sections, two side pieces and a floor, or bottom, member and the frame members are joined to gunwale, chines and keelson by lashings of sinew, whalebone, or hide, a method that, together with three-part frames, gives great flexibility to the framework. The frame of the early curragh may have been lashed, but because of the other fundamental differences in design and construction it was less flexible than that of the umiak.
The basic features of the umiak frame are not found in the kayak, the structure of which in most types approaches that of the curragh. The gunwale is the strength member in the kayak, and some types have a rather extensive longitudinal batten system as well. In only a few types of kayak is the keelson an important strength member, and even here the gunwales are of primary importance. The hypothesis has been offered that this indicates a different parentage for the kayak than for the umiak, and that the umiak represents the earlier type, it being argued that this type of boat was the one more required in migratory periods, and so would be first developed. Such theories should be accepted with caution, however, as the fundamentally different use requirements for the two types of craft might readily explain the variation in their principles of construction. Hunting would also have been necessary during migrations, as existence depended upon food; the earlier appearance of the umiak cannot be assumed on such limited grounds.
Figure 162
Fitting Split Walrus-Hide Cover to umiak at St. Lawrence Island, Alaska, 1930. (Photo by Henry B. Collins.)
