Proas are double hulled sailboats. Unlike a catamaran (two hulls of the same size) they feature a longer and a shorter one.
Originally, proas were developed in Oceania from dugout canoes by tying an additional log as stabilizer to one side and using a sail for propulsion (so don’t be confused if we talk about (outrigger-)canoes, it’s a sailing boat what’s in our mind). The early people of Oceania colonized the entire Pacific Ocean with their sailing canoes – more than one third of planet earth’s surface!
Sailing canoes are still the backbone of transportation, fishing and culture for many pacific island populations .
Pacific proas are somwhat special: they always keep their shorter hull to windward. Doesn’t sound to spectacular? Well, that means they can’t tack or jibe like conventional sailboats to change direction of travel! So how can proas travel oceans or even small ponds without the ability to turn the bow where the crew wants to go?
Instead of a tack or jibe proas change the direction they sail! This maneuver is called shunting (also known from railroads). Proas are designed to sail forward and … well forward. They come with two bows on each hull, both sides are sometimes bow or stern.
To be able to sail in both directions, the hulls, rudders and sails of proas are built fore-aft symmetric (bow and stern are shaped the same way) and port-starboard asymmetric (windward hull is smaller than leeward hull).