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NoBozo · 10-07-2010, 10:13 AM

The wire under the "A" frame is called a "Bobstay" and intended to prevent sag in the "A" Frame when it is near the horizontal position...when the dock is about to be raised. Technically, the bobstay wire keeps the plane of the "A" Frame "In Column". If the plane of the "A" Frame goes out of column, there is risk of buckling as mentioned above. If the "A" Frame were weightless, a bobstay would not be needed.

Iceboats have a "bobstay" ...with the little Strut just as in the dock "A" Frame, running fore to aft under the fusalage to keep it in column, as it resists down force from the mast and sail under load. BTW, if the "bobstay" is TOO tight, a compression fracture in the fusalage (the column) may result.

NB

PS: The picture was a big help in visualizing the situation.

10-07-2010, 10:13 AM	#8
NoBozo Senior Member Join Date: Jun 2008 Location: Portsmouth. RI Posts: 2,231 Thanks: 400 Thanked 460 Times in 308 Posts	The wire under the "A" frame is called a "Bobstay" and intended to prevent sag in the "A" Frame when it is near the horizontal position...when the dock is about to be raised. Technically, the bobstay wire keeps the plane of the "A" Frame "In Column". If the plane of the "A" Frame goes out of column, there is risk of buckling as mentioned above. If the "A" Frame were weightless, a bobstay would not be needed. Iceboats have a "bobstay" ...with the little Strut just as in the dock "A" Frame, running fore to aft under the fusalage to keep it in column, as it resists down force from the mast and sail under load. BTW, if the "bobstay" is TOO tight, a compression fracture in the fusalage (the column) may result. NB PS: The picture was a big help in visualizing the situation.