A dolphin striker is a spar mounted downward from the middle of the bowsprit. The bobstay is fastened to the stem of the ship and to the dolphin striker and the martingale stay is fastened to the dolphin striker and the forward end of the bowsprit. The purpose is to counteract the upward tension of the bowsprit from forestays. On some ships, the bobstay runs directly to the end of the bowsprit, lacking the dolphin striker and the martingale stay.
- Dolphin Striker at Wikipedia