Booms

Working out the correct proportions for these spars
The boom is a spar—usually wood or aluminum—along which the foot of a sail is stretched and fastened. Despite what many sailors think, it’s not true that a boom is named after the noise it makes when it hits your head during an accidental jibe. The fact is that boom is the Dutch word for tree or pole.Most booms are made of aluminum these days, of course, and here are the recommended minimum proportions:

• simple round aluminum booms: diameter, 1/45 of overall length; wall thickness, 1/26 of diameter

• elliptical-section booms: width (transverse section), 1/50 of length; height (vertical section), 1½ times width; wall thickness, 1/26 of width