Permanently Installed Preventer - The Case For

by Edwin G. Fischer, MD on 18 Jan 2008 The incidence of injury from accidental or premature jibes is unknown but the problem is not insignificant. (I became aware of the immediacy and seriousness of such accidents during the 1989 Marion Bermuda Race when a pediatrician at the helm of a fellow neurosurgeon’s boat had a fatal head injury during an accidental jibe at night. He was struck by the mainsheet as it whipped across the cockpit. The binnacle was also badly damaged by the mainsheet.

Subsequently I assembled an incomplete list of 18 fatal head and/or neck injuries that occurred on 'offshore' yachts during accidental jibes. A surprising number occurred in various racing venues, as follows.

Racing Venues with Well Documented Fatal Jibe Head Injuries
1979 SORC boom injury
1981 Practice - USCG Academy Sailing Team boom injury
1989 Marion Bermuda Race mainsheet injury
1992 Cowe’s Week mainsheet injury
1996 Antigua Race Week mainsheet injury
1998 Ft. Lauderdale-Key West Race boom injury
2007 Atlantic Rally for Cruisers (ARC) boom or mainsheet injury

In addition, in 1990 a midshipman at the US Naval Academy was in coma after a head injury during an accidental jibe and his recovery was not good enough to return to school.

Accidental jibes can be avoided only if a preventer is always in place. Phil Garland, of Hall Rigging, designed a permanently installed preventer that we have used with ease on our Morris 46 in four Newport Bermuda Races and 2 roundtrip transatlantic passages.

A Permanently-Installed Preventer (designed by Phil Garland)

A. Equipment
a. A pad-eye or bail on the undersurface of the boom, aft of the vang (about 1/3rd the distance from the gooseneck to the boom end, but the exact location is not critical)
b. Two blocks on the deck, one on each side, located in the vicinity of the shrouds (will vary with the boat)
c. Two line stoppers, one each side, located by the cockpit in easy reach of the helmsman
d. Two lines long enough (about half the length of the boom plus the distance from the deck block to the line stopper, plus several extra feet)

B. Set-Up
a. Both preventer lines start at the pad eye or bail on the boom, one running forward to the block and then aft to the line stopper on the starboard side, the other running similarly on the port side.
b. On our Morris 46, a piece of PVC tubing on the aft lower shroud prevents line chafe.

C. Operation
a. The entire system can be run by the helmsman: releasing the old leeward line from the stopper before or during the jibe and tightening the line in the stopper on the other side after the jibe.
b. The helmsman can also trim the line as the mainsheet is let out or taken in.
c. Occasionally, one of the lines hangs up on a Dorade.
d. Upwind both lines are slack and do not need attention.
e. The initial force of the jibe is minor compared to the full force of the jibe after the accelerating boom has crossed the centerline.

Above and below: Preventer lines set-up on a Morris 46 (DIVA)

Dr Fischer is Fleet Surgeon for the Cruising Club of America