A piece of sea wit, sported in hot weather. I am becalmed, the sail sticks to the mast; that is, my shirt sticks to my back. His prad is becalmed; his horse knocked up.
·Impf & ·p.p. of <<Becalm>>. ...
Webster's Dictionary of the English Language
Implies that from the weather being calm, and not a breath of wind blowing, the sails hang loose aga...
The Sailor's Word-Book