| 摘要 |
PURPOSE:To achieve the required bending rigidity and the mechanical strength, by forming the groove longitudinally of a pipe along the inner wall of the pipe tapered in the direction of the mast top. CONSTITUTION:A plurality of grooves 2 are formed longitudinally of a mast along the circumference of the inner wall of the mast body 1 made of a tapered pipe having the diameter decreasing gradually from the mast heel toward the mast top then a reinfocing rib 3 is fixed to said groove 2. Consequently even a mast made of FRP can be improved of the bending rigidity and the mechanical strength. |
