Multiple speed marine propulsion system
A marine stern drive and multi-speed transmission propulsion system in which a transmission, either manual or automatic, is interposed between the engine and stern drive extending at least partially outboard of the transom. A stern drive extension housing enclose the outboard transmission. The various embodiments may include automatic shifting, torque-absorbing couplings, dry oil sump and misalignment couplings. The system may be provided as an OEM item or as a retrofit and allows the engine to be maintained in its normal or original position thus enhancing the performance characteristics of the boat. The stern drive has forward, reverse and neutral shifting capabilities.
1. A method of fitting a stern drive to a boat, comprising the steps of:
(a) mounting an engine at a first location, said engine having an engine output shaft inboard of a transom of said boat;
(b) coupling a transmission to said engine output shaft of said engine;
(c) extending said transmission at least partly outboard through said transom of said boat;
(d) coupling said transmission to an input of a stern drive outboard of said transom; and
sealably coupling an extension housing to said transom of said boat to supportingly enclose within said extension housing a part of said transmission coupled to said input of said stern drive.
2. The method of claim 1 , wherein said transmission comprises a manual transmission shiftable between at least two gear ratios.
3. The method of claim 1 , wherein said transmission comprises an automatic transmission shiftable between at least two gear ratios.
4. The method of any one of claims 2 or 3 , wherein said manual transmission or said automatic transmission has a gear ratio shiftable over a range of about 1:1 to about 2:1.
5. The method of claim 3 , further comprising the step of shifting said automatic transmission between said at least two gear ratios with an electronic shift controller.
6. The method of claim 5 , further comprising the step of signaling said electronic shift controller to shift said automatic transmission between said at least two gear ratios.
7. The method of claim 6 , further comprising the step of generating a signal receivable by said electronic shift controller based upon a speed of said engine.
8. The method of claim 1 , wherein said step of coupling an extension housing to said transom of said boat to enclose within said extension housing a part of said transmission coupled to said input of said stern drive comprises the step of coupling a discrete extension housing to said transom of said boat to enclose within said extension housing a part of said transmission.
9. The method of claim 1 , wherein said step of extending said transmission at least partly outboard of said transom of said boat avoids relocating said engine from said first location inboard of said transom of said boat to a second location inboard of said transom of said boat.
10. The method of claim 9 , wherein said step of coupling a transmission to an engine output shaft of said engine comprises the steps of:
(a) uncoupling a first transmission from said motor output shaft of said engine; and
(b) coupling a second transmission to said motor output shaft of said engine.