| 摘要 |
A shallow draft boat has a hull that protects a propulsion propeller within a tunnel that passes only partially through the hull from stem to bow. The hull has a mechanism, such as a flap for selectively permitting or blocking water flow access to the tunnel from under the boat. The boat also has a lift mechanism for selectively positioning a propeller of a propulsion unit substantially directly behind the tunnel or below the tunnel. The boat can operate in two modes. In one, water access to the tunnel is permitted and the propeller is positioned above the bottom of the hull and behind the tunnel. In the other, water access to the tunnel is blocked and the propelles is positioned below the bottom of the hull. This construction permits selective operation in a shallow draft mode, in a normal draft mode or in between. In the shallow draft mode, the boat prevents propulsion unit malfunction by keeping obstacles, such as debris, crab pots and mammals such as manatees from contact with the propeller.
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