To provide a stabilizing and adjusting unit for hull direction which facilitates adjustment and maintenance of development angle of each boom and assembling and disassembling thereof.

A left and right pair of branching sails 71 branch like a crotch from a luff toward backward. Each of foot portion of the branching sail is installed on a left and right pair of booms 60 that can independently develop and move circularly in a lateral direction X. A pull rope 34 of which the middle part is hanged via a fixed portion of the hull is provided to the beam 60. The adjustment of its length permits free development and circular movement of each beam 60. The boom 60 is generally L shaped by a circular movement shaft part 61 and a turning shaft part 62 which is integrated with and extends from the circular movement shaft part 61 to the backward direction. A one end 35a of an adjustment rope 35 for development angle is tied to a rear end 62a of the turning shaft part. The other end 35b side of the adjustment rope 35 is tied to a front end 62b of the turning shaft part 62 of the other beam 60 by being wound therearound via the rear end 62a side of the turning shaft part 62 of the other beam 60. Adjustment of the adjustment rope 35 enables the development angle θ between each boom 60, 60 to be adjusted and maintained.