Masthead

The top end of the mast, often carrying a wind instrument, anchor light, VHF antenna, and sheave for the main halyard.

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Related M-terms

Marlinspike

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

MOB button

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

Magnetic

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

Mooring

A permanent ground tackle — anchor, chain, and buoy — to which a vessel can secure instead…

MFD

Multi-Function Display — a large chartplotter screen able to show radar, AIS, sonar, engin…

Mizzenmast

The shorter mast stepped aft of the mainmast on a ketch or yawl.

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