System and method for controlling a multi-speed transmission on a marine engine

A marine propulsion system for a marine vessel, the marine propulsion system comprising:

• an engine;
• a propeller configured to be coupled in torque-transmitting relationship with the engine;
• a transmission configured to transmit torque from the engine to the propeller at one of at least a first gear ratio and a second gear ratio;
• an engine speed sensor measuring a speed of the engine;
• a vessel pitch sensor measuring a pitch of the marine vessel;
• and
• a control module in signal communication with the engine speed sensor and the vessel pitch sensor;
• wherein the control module causes the transmission to switch between transmitting torque at the first gear ratio and transmitting torque at the second gear ratio based on a load on the engine, the engine speed, and the vessel pitch;
• and
• wherein the control module causes the transmission to transmit torque at the first gear ratio in response to the vessel pitch indicating that the marine vessel is off-plane, and causes the transmission to transmit torque at the second gear ratio in response to the vessel pitch indicating that the marine vessel is on-plane;
• wherein the first gear ratio is higher than the second gear ratio, and wherein the control module causes the transmission to switch from transmitting torque at the second, lower gear ratio to transmitting torque at the first, higher gear ratio in response to determining the following:
• the engine load is less than a predetermined engine load threshold;
• the engine speed is less than a predetermined engine speed threshold;
• and
• the vessel pitch is less than a predetermined minimum vessel pitch threshold, below which the marine vessel is estimated to be off-plane.

A method for controlling a multi-speed transmission for an engine powering a marine propulsion device on a marine vessel, the method being carried out by a control module and comprising:

• determining a load on the engine;
• determining a speed of the engine;
• determining a pitch of the marine vessel;
• and
• switching between a first gear ratio and a second gear ratio of the transmission based on the engine load, the engine speed, and the vessel pitch;
• wherein the marine propulsion device is one of multiple marine propulsion devices on the marine vessel;
• wherein the multiple marine propulsion devices are operable in an engine speed sync mode, in which an engine of each marine propulsion device is operated at the same engine speed;
• and
• further comprising disabling the engine speed sync mode while switching between the first gear ratio and the second gear ratio.