A sponson attachment for an airboat allows the airboat to increase its safety and stability very quickly. A method for attaching a sponson to an airboat hull includes attaching first and second flexible tethers to a side of the sponson. The method also includes removably securing the first flexible tether to an exterior of the airboat hull adjacent a gunnel, and removably securing the second flexible tether below the first flexible tether on the exterior of the hull.

Provided is an amphibious vehicle capable of maintaining stable vehicle posture by pitching control during cruising on water and also reducing wave drag caused by waves on water. The amphibious vehicle according to the present invention is characterized by being provided with: a vehicle body (11) capable of moving on sea and land; a front flap (14A) with one end portion secured to a lower end portion of the vehicle body (11) in such a manner that a principal surface is inclined with respect to a front surface (11a) of the vehicle body (11); and a rear flap (14B) with one end portion secured to a lower end portion of a rear surface (11b) of the vehicle body (11).

A marine vessel emergency airbag float device is provided. The device is designed to prevent the sinking of a boat or other vessel by deploying inflatable airbags in emergencies. The device comprises mounting brackets made from corrosion-resistant materials which are fastened to the vessel's sidewalls and symmetrically aligned for balanced flotation. The brackets feature attachment points for support members that hold airbags in an uninflated state. The airbags connect to compressed air tanks via tubing with one-way valves. Activation of the airbags are achieved either manually through user-operated controls or automatically via sensors that detect conditions such as capsizing, submersion, or flooding. As a result, the device facilitates rapid airbag inflation to stabilize the vessel, providing essential time for rescue or repairs.