Compensating for ambient torsional loads affecting marine vessel propulsion

A method for compensating torsional loads applied to a shaft coupled to a main engine, the method comprising:

• measuring a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• computing from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measuring at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, applying a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reducing moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, applying a compensating moment or load in the torque direction applied to the shaft by the main engine, or reducing moment or load applied in the opposite direction,
• wherein the method further comprises applying the compensating moment or load in the torque direction during a portion of the cycle and applying the compensating moment or load opposite to the torque direction during the portion of the cycle.

A method for compensating torsional loads applied to a shaft coupled to a main engine, the method comprising:

• measuring a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• computing from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measuring at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, applying a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reducing moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, applying a compensating moment or load in the torque direction applied to the shaft by the main engine, or reducing moment or load applied in the opposite direction,
• wherein the method further comprises applying a varying amount of compensating moment or load in the torque direction during a portion of the cycle.

A method for compensating torsional loads applied to a shaft coupled to a main engine, the method comprising:

• measuring a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• computing from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measuring at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, applying a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reducing moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, applying a compensating moment or load in the torque direction applied to the shaft by the main engine, or reducing moment or load applied in the opposite direction,
• wherein the method further comprises applying a constant amount of compensating moment or load opposite to the torque direction during a portion of the cycle.

A method for compensating torsional loads applied to a shaft coupled to a main engine, the method comprising:

• measuring a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• computing from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measuring at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, applying a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reducing moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, applying a compensating moment or load in the torque direction applied to the shaft by the main engine, or reducing moment or load applied in the opposite direction,
• wherein the method further comprises applying a varying amount of compensating moment or load opposite to the torque direction during a portion of the cycle.

A system for compensating torsional loads applied to a shaft coupled to a main engine of a ship, the system comprising a controller and coupled memory, said controller being adapted to:

• measure a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• compute from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• predict a value indicative of a future torsional load applicable on the shaft;
• generate a predicted timing indicative of a time at which the future torsional load is expected to affect the shaft;
• within a follow-up control time period occurring after measuring the group of values, measure at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, apply a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reduce moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, apply a compensating moment or load in the torque direction applied to the shaft by the main engine, or reduce moment or load applied in the opposite direction;
• and
• provide the compensating moment with a magnitude derived from the predicted value and in a time derived from the predicted timing.

A system for compensating torsional loads applied to a shaft coupled to a main engine, the system configured to:

• measure a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• compute from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measure at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, apply a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reduce moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, apply a compensating moment or load in the torque direction applied to the shaft by the main engine, or reduce moment or load applied in the opposite direction,
• wherein the system is further configured to apply the compensating moment or load in the torque direction during a portion of the cycle and apply the compensating moment or load opposite to the torque direction during the portion of the cycle.

A system for compensating torsional loads applied to a shaft coupled to a main engine, the system configured to:

• measure a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• compute from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measure at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, apply a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reduce moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, apply a compensating moment or load in the torque direction applied to the shaft by the main engine, or reduce moment or load applied in the opposite direction,
• wherein the system is further configured to apply a varying amount of compensating moment or load in the torque direction during a portion of the cycle.

A system for compensating torsional loads applied to a shaft coupled to a main engine, the system configured to:

• measure a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• compute from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measure at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, apply a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reduce moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, apply a compensating moment or load in the torque direction applied to the shaft by the main engine, or reduce moment or load applied in the opposite direction,
• wherein the system is further configured to apply a constant amount of compensating moment or load opposite to the torque direction during a portion of the cycle.

A system for compensating torsional loads applied to a shaft coupled to a main engine, the system configured to:

• measure a group of values indicative of torsional loads applied on the shaft or power demand from the main engine;
• compute from the group of values a value representing the torsional load over time and a parameter indicative of a cycle;
• within a follow-up control time period occurring after measuring the group of values, measure at least one subsequent value indicative of torsional loads applied on the shaft after the computing, and
• (1) if the at least one subsequent value is smaller than the value representing the torsional load over time, apply a compensating moment or load in a direction opposite to a torque direction applied to the shaft by the main engine, or reduce moment or load applied in the same direction;
• or
• (2) if the at least one subsequent value is greater than the value representing the torsional load over time, apply a compensating moment or load in the torque direction applied to the shaft by the main engine, or reduce moment or load applied in the opposite direction,
• wherein the system is further configured to apply a varying amount of compensating moment or load opposite to the torque direction during a portion of the cycle.