Spinnaker

A spinnaker is a special sail that is designed specifically for sailing downwind (with the wind behind the boat). A spinnaker resembles a parachute somewhat in both construction and appearance. It is constructed of very lightweight nylon fabric, often of a bright color. When deployed, it fills with wind and balloons out in front of the boat. A spinnaker operates by filling with air and pulling the boat along behind it. This is in contrast to a mainsail and jib, which power the boat using the principles of aerodynamics, by providing lift much as the wing of an aircraft does.

The spinnaker requires a spinnaker pole to stabilise one side (often the windward side) and to stop the sail collapsing in on itself. This pole must be deployed with the spinnaker whenever the sail is in use. Similarly it is stowed with the sail when the boat direction is other then a few points off down-wind.