Mainsheet

The control line that trims the mainsail in and out, running through a block system on the boom and a track or traveller.

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Related M-terms

Mainsail

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

Magnetic

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

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…

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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