overmast means to furnish with a mast or masts overly tall or heavy.
Etymology
From over- + mast.
verb
- To furnish with a mast or masts overly tall or heavy.“The double desire of being able to overtake a weaker flying enemy, or to escape when pursued by a stronger, has induced the owners to overmast their cruisers, and to spread too much canvass; […]”