mainmast's Usage Examples:

The legend (for it is nothing more) that Tromp hoisted a broom at his mainmast-head to announce his intention to sweep the English off the sea, refers to this period.

two shells struck her between the mainmast and after funnel, and a vast column of smoke and fire rose into the air.

Detail on the Bedford seal is hard to distinguish but both ships clearly had a square rigged mainmast and a lateen mizzen.

There were 2 to 4 triangular topsails above the yard onthe mainmast.

fore and aftree masts, square-rigged on the fore and mainmast and fore-and-aft rigged on the mizzen.