Lakatoi

For many years I've been intrigued by the images on the stamps of Papua New Guinea featuring an unusual sailing vessel, but I've never taken the time to look up what they are.  Until today.

The local term is "lakatoi" (literally "three dugouts"); the dugouts are harnessed together with booms, creating craft that are stable for oceanic travel.  The sails are "crab-claws."

Crab-claw sails were invented by the Austronesians somewhere in Island Southeast Asia by at least 2000 BCE. It spread with the Austronesian migration to Micronesia, Island Melanesia, Madagascar, and Polynesia. It may have also caused the unique development of outrigger boat technology due to the necessity for stability once crab claw sails were attached to small watercraft. Crab claw sails can be used for double-canoe (catamaran), single-outrigger (on the windward side), or double-outrigger boat configurations, in addition to monohulls.

Crab claw sails are rigged fore-and-aft and can be tilted and rotated relative to the wind. They evolved from "V"-shaped perpendicular square sails (a "double sprit") in which the two spars converge at the base of the hull. The simplest form of the crab claw sail (also with the widest distribution) is composed of a triangular sail supported by two light spars (sometimes erroneously called "sprits") on each side. They were originally mastless, and the entire assembly was taken down when the sails were lowered...

Another evolution of the basic crab claw sail is the conversion of the upper spar into a fixed mast. In Polynesia, this gave the sail more height while also making it narrower, giving it a shape reminiscent of crab pincers (hence "crab claw" sail). This was also usually accompanied by the lower spar becoming more curved.

Austronesians traditionally made their sails from woven mats of the resilient and salt-resistant pandanus leaves. These sails allowed Austronesians to embark on long-distance voyaging. In some cases, however, they were one-way voyages. The failure of pandanus to establish populations in Easter Island and New Zealand is believed to have isolated their settlements from the rest of Polynesia.