Topcat

The Topcat is a one-design sailing catamaran boat class which is divided into several boat sizes.
General.
The Topcat sailing catamarans are fast, seaworthy, popular, and affordable twin-hull boats ranging in size from 3.60 m (12 ft) to 5.50 m (18 ft). They have world-wide distribution and are differentiated by:
Design.
The Topcat lacks the dangerous main boom, as well as daggerboards, 
spreaders, shroud adjusters,
and other complicated trimming mechanisms.
To compensate for the missing daggerboards, the hull profiles are narrow and deep, and form
a keel, similar to the Dart 18 and other beach catamarans. This is a compromise between lateral stability, agility in maneuvers, and ability to run up the beach. The material of the hulls 
is fiberglass, with a strength of a few millimeters on top and on the upper sides.
Extra material is applied in areas subject to abrasion and stress forces: at the keel, and where the beams, shrouds, and rudders connect to the hulls.
There are special boat versions with a build-up keel for sailing schools and for sailing areas with coral reefs. The surface of the hulls is covered by a gelcoat.
Each hull has a dry storage compartment accessible by sealed hatch covers.
The aluminum beams are plugged into the hulls, and the assembly is held together by a tightly laced trampoline. The trampoline consists of two sheets of fabric. Each sheet has a round rubber edge that is threaded into an aluminum rail connected to the hull. The trampoline is laced in the middle, similar to a corset.
For safety the front beam contains a line to assist in righting the boat after capsizing.
The rudders do not have to rotate upwards in low water, but slide upwards inside their 
cheek plates when a retaining line is pulled. The boat can still be steered when the rudders 
are at the keel line, this allows sailing in areas with low water levels.
The rigging consist of an aero-dynamically shaped aluminum mast held by a forestay and two shroud wires.
The mast sits on top of a round knob riveted to the front beam, and rotates freely.
The K1 and Spitfire models have diamond spreaders to stabilize the mast.
Some masts can be divided into two parts for easier transportation.
There is a trapeze for the crew and/or helmsman.
There are three sail types available:
The Streamcut and PenTex sails have a larger sail area, and an almost rectangular shape.