Abstract: An inflated flotation collar is formed around at least part of the hull of a boat by positioning a longitudinal inflatable member along at least part of the length of both the port and starboard sides of the hull. The terminal portions of the member are secured so that the linear length of the gunwale over which the member extends is substantially fixed and so that the member is held substantially at gunwale level on the hull by securing devices passing around and optionally over but not under the hull. The inflatable member is inflated, whereby the expansion of the member causes the member to bear against the hull against the restraining effect of the securing of the terminal portions.