- any of various lines set up to reinforce or relieve ordinary running or standing rigging.
- a line for preventing a sail from jibbing.
Examples from the Web for preventer
A ship hove-to with preventer tackles on the rudder-head is unmanageable.The Mutiny of the Elsinore|Jack London
The only safeguard lies in rigging a preventer stay that will set up with a tackle, the fall leading inboard.
Breck tells us that his dope was planned to be a counter-irritant after being bitten as well as a preventer of bites.On the Trail|Lina Beard and Adelia Belle Beard
Through the preventer stern-post, reeve guys, and at the fore part of them fix tackles, and then put the machine overboard.The Seaman's Friend|Richard Henry Dana
It was formerly a custom to fit two bobstays, a regular one and a smaller one, called a preventer.