Possible Clues:

• Wild animals grab one and use it to move the boat
• Animal is redrawn on large canvas sheet
• Post held in South Africa, once a principal means of propulsion
• Large canvas from market in East coast state, say
• Lowest canvas on the principle mast
• It's above a boom
• Canvas old woman at auction talked of
• Water supply trouble? You can get that on yacht
• Ship's primary canvas
• Canvas home -- it's in the post