Mainmast

The taller (main) mast on a vessel with more than one mast.

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Related M-terms

Magnetic

Referring to the magnetic north pole rather than true geographic north.

Mainsail

The principal sail set on the (main) mast of a sloop, cutter, ketch, or yawl.

Maststep

The fitting (on deck or on the keel) into which the foot of the mast is stepped.

MMSI

Maritime Mobile Service Identity — a unique nine-digit number issued to each DSC-VHF/HF ra…

MOB button

A dedicated button on a GPS, chartplotter, or autopilot that marks the current position th…

Marlinspike

A tapered metal spike used to loosen knots, open rope lays, and work splices.

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