Windlass

A windlass (winch) can be fitted on to the sailboat in order to multiply the hand strength of the sailor, for the purpose of adjusting the sails. 

Autohelm

The Autohelm has a small joystick similar to a video game control, that can be used to steer the boat.

Sip 'n Puff

The sailor can use their breath to steer the sailboat and trim the sails, by inhaling or exhaling gently into straws, one straw for steering, and one straw for controlling the sails.

In this way high-level quadriplegics – those with no movement below the neck – can independently sail the sailboat.