Johnson Evinrude Outboard Motors 1956-1970 1.5-40hp repair manual., Page 14Get this manual
5- Coast Guard Approved equipment is equipment which has been approved by the Commandant of the U.SCoast Guard and has been determined to be in compliance with Coast Guard specif ica tions and regulations relating to the materials, construction, and performance of such equipment1-7 HORSEPOWER The maximum horsepower engine for each individual boat should not be increased by any great amount without checking requirements from the Coast Guard in your areaThe Coast Guard determines horsepower requirements based on the length, beam, and depth of the hullTAKE CARE NOT to exceed the maximum horsepower listed on the plate or the warranty and possibly the insurance on the boat may become void1-8 FLOTATION If your boat is less than 20 ftoverall, Coast Guard or BIA (Boating Industry of America) now changed to NMMA (National Marine Manufacturers Association) requirement is that the boat must have buoyant material built into the hull (usually foam) to keep it from sinking if it should become swampedCoast Guard requirements are mandatory but the NMMA is voluntary"Kept from sinking" is defined as the ability of the flotation material to keep the boat from sinking when filled with water