Marine speedometer

Abstract

A low drag impeller wheel mounted in an enclosure which when installed in the hull of a ship will rotate through the force of water acting upon it, and operate magnetically a pulse generating mechanism that through a current responsive instrument will indicate the speed of the vessel.

I claim: 
     
       1. A marine speed indicator comprising an impeller having an axis of rotation and blades which rotate about an axis, a magnet on at least one of said blades, and a magnetically operated switch in proximity to said impeller, a solid state circuit being actuated by said magnetically operated switch which actuation is caused by the rotation of said magnet in proximity to said switch, said solid state circuit including at least one transistor with base, emitter and collector; a power source; a capacitor; a zener diode, rectifier means, and a meter, said base being coupled to said magnetically operated switch; said zener diode being connected between said collector and said emitter with said zener diode being in series with said power source; said capacitor having a terminal in common with said zener diode and another terminal in common with said rectifier means; and said meter being in series with the rectifying means. .Iadd. 2. A marine speed indicator, comprising; a substantially cylindrical tubular housing, one end of which is open and the other end of which is closed by a member having a substantially planar surface facing said open end with a hollow gap therebetween, said housing having a longitudinal axis, an impeller supported by said housing intermediate said ends thereof and mounted for rotation about an axis that is substantially perpendicular to said longitudinal axis and spaced from the walls of said housing and said planar surface, said impeller comprising a plurality of vanes, at least one of which contains and supports a magnet for rotation therewith, and means responsive to movement of said magnet for generating a signal which is proportional to rotational movement of said impeller. .Iaddend..Iadd. 3. The indicator according to claim 2, wherein; said vanes are affixed to a cylindrical hub with at least the innermost portions of said vanes extending in a tangential direction from said cylindrical hub. .Iaddend..Iadd. 4. The indicator according to claim 3, wherein; said magnet is mounted on the exterior of said vane. .Iaddend..Iadd. 5. The indicator according to claim 4, wherein; said means comprises a reed switch. .Iaddend. .Iadd. 6. The indicator according to claim 5, further comprising; electronic circuit means responsive to the opening and closing of said reed switch for generating a signal proportional thereto. .Iaddend..Iadd. 7. The indicator according to claim 2, wherein said magnet is mounted on the exterior of said vane. .Iaddend..Iadd. 8. The indicator according to claim 7, wherein said means comprises a reed switch. .Iaddend..Iadd. 9. The indicator according to claim 8, further comprising; electronic circuit means responsive to the opening and closing of said reed switch for generating a signal proportional thereto. .Iaddend.