Bobstay

A bobstay is a part of the rigging of a sailing boat or ship.

Its purpose is to counteract the upward tension on the bowsprit from the jibs and forestay.

A bobstay may run directly from the stem to the bowsprit,[1] or it may run to a dolphin striker, a spar projecting downward, which is then held to the bowsprit or jibboom by a martingale stay.

The dictionary definition of bobstay at Wiktionary

Schematic view of the bow of a ship, showing: A the martingale stay , B the dolphin striker and C the bobstay .
Bows of HMS Victory : three parallel bobstays, separate dolphin-striker with martingale stays.