A small boat or the like comprising a flotation chamber defined at its gunwale by a first member, preferably integral with the sides of the hull extending upwardly and defining a first lip at its terminal end portion, a second member or cover secured at its bottom portion to the hull and extending inwardly of the first member with its upper end portion extending over the first member and including a second lip, and a connecting device resiliently engaging the first and second lips with each other to secure flotation material in the form of a block of expanded polystyrene or the like within the flotation chamber. The connecting device can be a separate element pressing the lips of the first and second members against each other or can be a resilient portion of one of the members normally biasing the lips into engagement. A rub rail is defined at the upper end of the flotation chamber and can be formed either by a separate connecting member or by a portion of one of the other members.