Dictionary
mast' clamp"
Naut.
1. a pierced slab of hardwood built into the deck structure of a small ship or boat to receive the force of the mast, which is fitted tightly through it.
2. Also called
mast hasp. a metal collar fitted to a thwart of a small boat to steady a mast.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.