A truck is a wooden ball, disk, or bun-shaped cap at the top of a

mast Mast, MAST or MASt may refer to: Engineering * Mast (sailing), a vertical spar on a sailing ship * Flagmast, a pole for flying a flag * Guyed mast, a structure supported by guy-wires * Mooring mast, a structure for docking an airship * Radio mas ...

, with holes in it through which flag

halyard In sailing, a halyard or halliard is a line (rope) that is used to hoist a ladder, sail, flag or yard. The term ''halyard'' comes from the phrase "to haul yards". Halyards, like most other parts of the running rigging, were classically made of ...

s are passed. Trucks are also used on wooden

flagpole A flagpole, flagmast, flagstaff, or staff is a pole designed to support a flag. If it is taller than can be easily reached to raise the flag, a cord is used, looping around a pulley at the top of the pole with the ends tied at the bottom. The fla ...

s, to prevent them from splitting. Without a masthead truck, water could easily seep into the circular growth rings of a wooden mast. However, the grain in the truck is perpendicular to that of the mast, allowing the water to run off it.

References

{{Sail Types Sailing rigs and rigging Sailing ship components