Andy - As I have always understood matters to brail a sail was to stow a loosefooted sail (ie no boom) up against the gaff or sprit ( see the Thames Barges, or Medway Bawleys. As This stow is conducted by hoisting up rather than furrling down on to the boom. It tended to be used by those commercial boats that relied upon minimum crews.

Traditionaly the Thames barge - upto about 150 ton burden was crewed by two men and a dog.

Gareth