Catamaran
A catamaran is a boat consisting of two
hulls joined by a frame. Catamarans can be sail- or engine-powered.
The catamaran was the invention of a fishing community in the southern
coast of India.
Catamarans are a relatively recent design
of boat for both leisure and sport sailing, although they have been
used for millennia in Oceania, where Polynesian catamarans and outrigger
canoes allowed seafaring Polynesians to settle the world's most far-flung
islands. Catamarans have been met by a degree of scepticism from some
sailors accustomed to more "traditional" designs.
The modern catamaran came from the South Pacific. English visitors applied
the Tamil name catamaran to the swift, stable sail and paddle boats
made out of two widely separated logs and used by Polynesian natives
to get from one island to another.
Other important builders
of catamarans are Austal and Incat both of Australia, best known for
building large catamarans both as civilian ferries and as naval vessels.
Although the principles of sailing are the same for both catamarans
and monohulls, there are some "peculiarities" to sailing catamarans.
The Catamaran can be harder
to tack. All sailboats must resist lateral movement in order to sail
in directions other than downwind.
catamaran does this by the
design of the hull giving comparatively little resistance to forward
motion and much resistance to lateral motion. This lateral resistance
is all along the hull, as opposed to most sailboats having a central
keel projecting deep into the water from the center of the boat.
While the catamaran’s method
allows it to sail into shallower waters, it has the negative effect
of placing lateral resistance at the bow and stern, far from turning
axis of the boat, where the intended lateral resistance becomes a turning
resistance due to the distance the bow and stern have to move in order
to complete a turn.
Regular sailboats, with
their deep lateral resistance occurring near the turning axis of the
boat, have much less turning resistance. Also, because catamarans are
lighter in proportion to their sail size, they have less momentum to
carry them through the turn when they are head to wind. Correct use
of the jib sail is often essential in successfully completing a tack
without ending up stuck in irons (pointing dead into the wind and sailing
backwards.
Catamarans are less likely
to capsize in the classic 'beam-wise' manner but often have a tendency
to 'pole-axe' instead - where the leeward (downwind) bow sinks
into the water and the boat 'trips' over forward, leading to a capsize.
Catamarans make good cruising
and long distance boats: The Race (around the world, in 2001) was won
by the giant catamaran Club Med skippered by Grant Dalton. It went round
the earth in 62 days at an average speed of eighteen knots.
|
