A dolphin striker (an older term for a martingale boom or simply as a martingale; sometimes called a striker) is a small vertical or near vertical ancillary spar spanning between the bowsprit and martingale thereby redirecting the direction of the tension in the forward end of the martingale slightly more vertically. This vertical component is necessary to more effectively oppose the forestays' mostly upward tension on the forward end of the bowsprit than would be the case in the absence of the dolphin striker.
Around 1813 some large sailing vessels experimented with double strikers: these had two downward-pointing spars forming an inverted V in the middle of the bowsprit. However, the practice was short-lived as it did not seem to provide any additional benefit. The dolphin striker's length was typically half the length of the spritsail yard or, when spreaders were used, the same length as one spreader.
- "Dictionary of Wisconsin History - Term: dolphin striker (maritime)". Wisconsin Historical Society. Retrieved 10 January 2010. "A short spar perpendicular the bowsprit, used with martingales for holding down the jib-boom. The position is such that a dolphin leaping at the bow of a vessel could possibly be struck by this spar."
- Lees, James (1984). The Masting and Rigging of English Ships of War, 1625-1860 (Second ed.). Naval Institute. p. 32. ISBN 9780870219481.
- "Rules and Restrictions Imposed on Cobra 5 Metre Catamarans as amended to January 1996". Australian Cobra Catamaran Association. January 1996. p. 3. Retrieved 10 January 2010.