Abstract: A chair apparatus particularly useful by crew members in oceangoing powerboats has a seat assembly attached to a support flange assembly. The support flange is adjustably coupled to an upstanding support member which is fixed to a support surface to allow the seat assembly to be moved vertically along the upstanding support member. The side portions of the seat assembly are adjustable in and out to accommodate the width of a particular occupant. A posterior support extension is hinged to the front portion of the seat assembly to provide increased sitting space when, for example, the boat is not racing. The posterior support extension is rotated downward and out of the way when the boat is racing. A non-rebound impact absorption pad is attached to the interior surfaces of the seat assembly. The pad has a plurality of layers of visco-elastic foam, each layer having a different degree of firmness.