Patent ID: 7931511
Filing Date: 2011-04-26
Classification: B63H

Abstract:
1. A boat propulsion system comprising: an engine; a propeller arranged to be driven by the engine; an acceleration detection section arranged to detect an acceleration command from a user; a gear shift mechanism arranged to transmit a driving force generated by the engine to the propeller at one of at least a low speed reduction ratio and a high speed reduction ratio; and a control section arranged to perform control so as to shift the speed reduction ratio of the gear shift mechanism based on a gear shift control map in which the acceleration detection section detects an acceleration command from the user; wherein the gear shift control map shifts the speed reduction ratio of the gear shift mechanism based on a plurality of parameters; wherein the gear shift control map includes at least two gear shift control maps, the control section is arranged to select one of the at least two gear shift control maps to shift the speed reduction ratio according to the acceleration command from the user; the at least two gear shift control maps include a first gear shift control map and a second gear shift control map; the first gear shift control map corresponds to a high fuel efficiency mode in which the speed reduction ratio of the gear shift mechanism is shifted to a different speed reduction ratio at a predetermined engine speed in which the acceleration detection section detects that the acceleration command from the user is less than a predetermined level; the second gear shift control map corresponds to a high acceleration mode in which the speed reduction ratio of the gear shift mechanism is shifted to a different speed reduction ratio at an engine speed that is higher than the predetermined engine speed in which the acceleration command from the user is more than the predetermined level; and the control section is arranged to select one of the first gear shift control map and the second gear shift control map based on a lever opening degree of a control lever portion and the acceleration command from the user detected by the acceleration detection section.