drive, which he subsequently patented. The first commercial introduction of sterndrives was the Volvo Penta "Aquamatic" at the 1959 New York Motor Boat Show. Kiekhaefer introduced a MerCruiser outdrive in 1961 at the Chicago Boat Show. By 1962, 16 manufacturers were producing sterndrives. There was also the Outboard Marine Corporation (O.M.C.); however, due to several patent wars, O.M.C. ceased production. Characteristics Advantages of the sterndrive system versus outboards include higher available horsepower per engine and a clean transom with no cutouts for the outboard installation and no protruding powerhead, which makes for easier ingress and egress for pleasure boat passengers, easier fishing and easier retrieval in rescue situations. Advantages of the sterndrive system versus inboards include simpler engineering for boatbuilders, eliminating the need for them to design propshaft and rudder systems; ease of trailering and shallow water maneuvering (with the drive trimmed up); also, a significant space savings with the engine mounted all the way aft, freeing up the boat's interior volume for occupancy space. This is of particular significance to consumers who are interested in "pocket cruisers," boats which have amenities like a head, a galley, and separate sleeping quarters in a boat less than 30 feet in length. The main disadvantages of sterndrives versus straight inboards is that they are more exposed. There are hoses, rubber bellows and oil lines in the water which can be damaged. There are also more components in the water which are exposed to corrosion. Maintenance on I/Os is more complicated than outboards in several ways, less in others. While sterndrive engines are not as readily removable as smaller outboards, larger outboards (which combine both large powerheads and outdrives) are bigger, bulkier, and heavier than separate engine and outdrive components on sterndrives. Sterndrive engine compartments may be cramped; however components are neither as tightly engineered nor physically as compressed and densely packed as outboards, which all must fit under a streamlined integrated cover. With both inboards and stern drives there is a fire and explosion hazard from gasoline fuel vapors within the engine compartment. Typically these boats must run a blower for several minutes prior to starting the engine, and when idling or moving below cruise speed. The blower exchanges the air within the engine compartment with fresh outside air. Because of their practical advantages and attractive cost, sterndrives have become extremely popular especially for use in pleasure boats, and there are many