Abstract: A marine vehicle includes a hull, a rudder, a propeller, a swirl generator mounting region provided on an outer surface of the hull and located on a port side or a starboard side where a rotation direction of the propeller is downward, and a pre-swirl generator having a swirl creating wedge disposed in the swirl generator mounting region. The swirl generator mounting region is disposed in front of a central axis of the rudder and behind a vertical line spaced from the central axis by a distance that is 0.2 times the length of the vehicle. The swirl creating wedge is inclined with respect to a waterline by an angle (?1) of 13°-45°. The pre-swirl generator can produce a flow guiding effect that enhances propulsive efficiency of the marine vehicle.

Abstract: A marine vehicle includes a hull, a rudder, a propeller, a swirl generator mounting region provided on an outer surface of the hull and located on a port side or a starboard side where a rotation direction of the propeller is downward, and a pre-swirl generator having a swirl creating wedge disposed in the swirl generator mounting region. The swirl generator mounting region is disposed in front of a central axis of the rudder and behind a vertical line spaced from the central axis by a distance that is 0.2 times the length of the vehicle. The swirl creating wedge is inclined with respect to a waterline by an angle (?1) of 13°-45°. The pre-swirl generator can produce a flow guiding effect that enhances propulsive efficiency of the marine vehicle.

Abstract: A valve assembly with low gas level signaling and controlling function includes a primary valve threadedly engaged with an outlet of a tank, the primary valve being formed with a recess in which is fitted a plunger having an upper end extending upwardly through the primary valve to engage with a knob, a low level linking device comprising a tubular tube connected with a bottom of the primary valve, a flexible rod having an end extending upwardly through the tubular tube to connect with the primary valve and another end connected with an end of a float rod, and a float connected with another end of the float rod, and a release rod connected a pusher which is operatively connected with the primary valve so that when the release rod is turned, the pusher will move down the flexible rod to open the primary valve, whereby the valve assembly can detect the amount of gas remaining in a gas tank and will close when the level has decreased to a certain level thereby alerting the users and enabling them to replenish th

Abstract: A valve assembly with low gas level signaling and controlling function includes a primary valve threadedly engaged with an outlet of a tank, the primary valve being formed with a recess in which is fitted a plunger having an upper end extending upwardly through the primary valve to engage with a knob, a low level linking device comprising a tubular tube connected with a bottom of the primary valve, a flexible rod having an end extending upwardly through the tubular tube to connect with the primary valve and another end connected with an end of a float rod, and a float connected with another end of the float rod, and a release rod connected a pusher which is operatively connected with the primary valve so that when the release rod is turned, the pusher will move down the flexible rod to open the primary valve, whereby the valve assembly can detect the amount of gas remaining in a gas tank and will close when the level has decreased to a certain level thereby alerting the users and enabling them to replenish th