Function
On a proa, the ama may provide lift or ballast, depending on whether it is designed to be used to leeward or windward; on a trimaran it is designed primarily to provide lift. There are many shapes of ama; those used in proas are generally laterally symmetric, as the proa is designed to sail with either end forwards, while trimaran ama are one-directional and may have no axis of symmetry.
The most advanced ama are composed of highly curved surfaces which generate lift when driven forward through the water, much like an airplane wing. This lift may be directed to the windward, used to counter slipping to leeward, or may be oriented vertically to counter heeling forces from the sailing rig. These highly-curved structures are much more difficult to manufacture than traditional ama, and are therefore more expensive. The Bruce foil is an example of a type of leeboard often attached to an ama to assist in producing lift.
Read more about this topic: Ama (sailing)
Famous quotes containing the word function:
“Our father has an even more important function than modeling manhood for us. He is also the authority to let us relax the requirements of the masculine model: if our father accepts us, then that declares us masculine enough to join the company of men. We, in effect, have our diploma in masculinity and can go on to develop other skills.”
—Frank Pittman (20th century)
“Literature does not exist in a vacuum. Writers as such have a definite social function exactly proportional to their ability as writers. This is their main use.”
—Ezra Pound (1885–1972)
“Morality and its victim, the mother—what a terrible picture! Is there indeed anything more terrible, more criminal, than our glorified sacred function of motherhood?”
—Emma Goldman (1869–1940)