(ii) The greater the distance B—C between dug-out and outrigger float, the greater the stability of the canoe. Since the momentum of rotation is the product of B—C (Fig. I), and the weight of the log C, it is clear, therefore, that the greater the distance, the greater will be the momentum. Too great a distance, however, would interfere with the wieldiness of the canoe. Any force acting on the log would easily tip the canoe, and as the natives, in order to manage the craft, have to walk upon the outrigger, the distance B—C must not be too great. In the Trobriands the distance B—C is about one-quarter, or less, of the total length of the canoe. In the big, sea-going canoes, it is always covered with a platform. In certain other districts, the distance is much bigger, and the canoes have another type of rigging.
(iii) The size of the log (C) of which the float is formed. This, in sea-going canoes, is usually of considerable dimensions. But, as a solid piece of wood becomes heavy if soaked by water, too thick a log would not be good.
These are all the essentials of construction in their functional aspect, which will make clear further descriptions of sailing, of building, and of using. For, indeed, though I have said that technicalities are of secondary importance, still without grasping them, we cannot understand references to the managing and rigging of the canoes.
The Trobrianders use their craft for three main purposes, and these correspond to the three types of canoe. Coastal transport, especially in the Lagoon, requires small, light, handy canoes called kewo’u (see Fig. II (1), and Plates XXIV, top foreground, and XXXVI, to the right); for fishing, bigger and more seaworthy canoes called kalipoulo (see Fig. II (2), and Plates XXIV, and XXXVI, to the left, also XXXVII) are used; finally, for deep sea sailing, the biggest type is needed, with a considerable carrying capacity, greater displacement, and