Green’s Dictionary of Slang

boltsprit n.

the nose.

1690		T. Shadwell Amorous Bigot in Complete Works V (1927) 71: As thou lovest thy ears, or nose, that bolt-sprit of thy face, prophane not my inviolate Whiskers.
c.1698		B.E. Dict. Canting Crew n.p.: Boltsprit a Nose.
1709		N. Ward A Compleat and Humorous Account of all the Remarkable Clubs (1756) 24: A Merry Gentleman, who had often hazarded his own Bolt-sprit, be steering a vitious Course among the Rocks of Venus, having observed [...] that abundance of both Sexes had sacrificed their Noses to the God Priapus.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.

In phrases

break one’s boltsprit (v.)

to lose one’s nose as a result of syphilis.

c.1698

B.E. Dict. Canting Crew n.p.: He has broke his Boltsprit, has lost his Nose with the Pox.