mainmast:

usually, the principal and the heaviest mast of two or more. In yawls and ketches, the forward mast is the mainmast; in schooners and vessels with more than two masts, it is the second mast from forward.

mainsail (main):

the sail which is attached to the mast and boom, usually the biggest working sail; often called simply the main.

marconi:

the name of a three-cornered sail whose luff sets on a mast-as opposed to the four-sided gaff-rigged sail; also called a Bermuda or jib-headed sail.

mean high water:

the average level of high tide for any area.

mean low water:

the average level of low tide for any area.

make fast:

to secure a line to an object; to doubly secure a cleated or otherwise tied-line by means of an added hitch.

marline:

a two-stranded nautical twine.

marlinespike:

a pointed metal tool used in splicing.

marry:

to unlay the ends of two lines and interlace the strands alternately, prior to splicing them.

MegaHertz (mHz):

a unit, equal to one million cycles per second, used to describe radio frequency.

mizzen:

the sail set on the aftermast of a yawl or ketch.

monel:

a strong, rust-resistant metal alloy composed of approximately 67 per cent nickel, 28 per cent copper and 5 per cent iron and manganese; commonly used for fastenings, propellers and parts of metal instruments.

mooring:

an anchor or weight, permanently attached to the sea floor, with a buoy going to the surface, used to hold the boat in a certain area

nautical mile:

6,080 feet

measure of length at sea (2025 yards). 1 mile = 1,760 yards.

neap tide:

a tide of less than average range, occurring at the first and third quarters of the moon.

null:

the compass point at which a radio direction finder's directional antenna receives the weakest signal from a given RDF station, thereby indicating the station's bearing.

offing:

seaward, a safe distance from shore.

omni:

a navigation system that provides bearings by means of a VHF radio signal: also known as visual omni range (VOR). The system was originally designed for aviators, but it's also used by mariners.

outhaul:

line used to pull out the foot of a sail

usually a line or tackle, an outhaul is used to pull the clew of the mainsail towards the end of the boom, thus tightening the foot of the sail.

overcast stitch:

a stitch that binds a fabric edge. It is made by drawing the needle through the fabric from the wrong side to the right side about 1/8 inch below the edge, then returning the needle to the wrong side-bringing it over the edge, not through the fabric-and then drawing it through from wrong to right side again.

painter:

a line tied to the bow of a small boat for the purpose of securing it to a dock or to the shore.

pay out:

to slacken on a line.

pedestal:

a vertical post in the cockpit used to elevate the steering wheel into a convenient position.

pennant:

a triangular flag.

phosphorescence:

luminescence.

piano hinge:

a narrow rectangular hinge with a small-diameter pin and numerous holes for screws; used for joining two edges that require support all along their lengths.

pinch:

to sail as close as possible towards the wind.

pintle:

metal pin on which the rudder is hung.

pitch:

plunging of a vessel fore and aft.

point:

to turn closer towards the wind (point up).

port:

left side

the left side of the boat, looking forward; also, a contraction for porthole.

port tack:

sailing with the wind coming from the port side, with the boom on the starboard side.

preventer:

line and tackle which limits the movement of the boom, usually for the purpose of preventing accidents by preventing being swept overboard in severe conditions.

privileged vessel:

the ship with the right of way.

pulpit:

a metal framework on deck at the bow or stern. Provides a safety railing and serves as an attachment for the lifelines.

quarter:

the side of a boat aft of beam and forward of the stern

either side of a boat's stern; to sail with the wind on the quarter.

quay:

wharf used to discharge cargo.