Prepared For:

Sailing Club of the Chesapeake

Presented by: Chuck O’Malley, Doyle Chesapeake Sailmakers

Accidental Gybes…

The ever present threat ! 40% of all Sailing Injuries come from being hit by the

Boom or Mainsheet.

A quick internet search paints a very grim picture!

Well over 20 fatalities from Accidental Gybes in the past 20 years.

There is a very good chance each of us here has known someone who has passed tragically or suffered a severe injury from an Accidental Gybe.

We don’t stand a chance In 15 knots of breeze the Clew of the typical 35 foot

sailboat’s main has about 1,050 lbs of load.

The human skull can be fractured by a blow of between 75 and 250 PSI.

Even a glancing blow or being hit by the mainsheet can be deadly.

While at Sea, even with medical help on board, there is very little that can be done to save someone.

“ An Ounce of Prevention is Worth a Pound of Cure”

Preventers, Boom Brakes, Vangs Often thought of as the same – they are not.

Vangs are used to control mainsail twist.

Boom Brakes are an aid for controlled Gybing. In general use they restrict the speed with which the boom crosses the boat while gybing.

Preventers are designed to prevent the boom from crossing the boat in the event of an unplanned gybe.

Vangs Vangs are often used as Preventers. It is common to

use a block and tackle with a snap shackle attached to a toe rail or pad eye.

This can do the job in light air or on small boats.

The vang set up tends to pin the boom in place and if the boom gets buried in the water, there is a good chance something is going to break.

There are better options, regardless of the size of the boat.

A Better Approach

- Low Tech

- High Tech

Simple Friction Boom Brakes

Wichard’s Gyb’ Easy Maximum working load 2,650 lbs.

Recommended for mains up to 500 Sq. Ft.

Controls the booms motion by using friction.

Capable of locking the boom in place.

Costs $ 270.00.

Mechanical Boom Brakes

Dutchman’s Boom Brake

Three different model Sizes 250 Sq. FT. / 500 Sq. Ft. / 750 Sq. Ft.

Rated Safe Working Loads 1600 lbs. / 2700 lbs. / 4100 lbs.

Controls Boom Motion through friction on line and Sheaves.

Capable of Locking Boom in place.

Cost $ 500 to $ 1000

Standard Block and Tackle Arrangements

Traditional PreventersMid Boom End of Boom

Less Complicated

May Pin Boom down

Potential Damage to Boom

Good for Coastal and Inshore

Reasonable Price

More Complicated

Allows Boom to Raise Freely

Boom and Gooseneck Safe

Reliable Offshore Set up

Reasonable Price

End of Boom Preventer

Hall Spars – Mid Boom Preventer

A Little Knowledge Goes a Long Way

Know Your Loads

35 Foot Sailboat 50 Foot Sailboat

Main Area = 300 Sq. Ft.

Clew Load = 1,053 lbs in 15 Kts

Clew Load = 2,368 lbs in 30 Kts

Typical safety margin 60%

Looking for 3,950 lb rating

Main area = 600 Sq. Ft.

Clew Load = 2158 lbs in 15 Kts

Clew Load = 4,632 lbs in 30 Kts

Typical Safety Margin 60%

Looking for 7,700 lb rating

Things to think about ?

Strength of Attachments

Strength of fittings and Blocks

Look at using Nylon Line

Design should think about weak link to protect expensive parts

Ease of use

Ability to leave it set up

Type of cruising you do

Consequences of no Preventer

Can it be handled from Cockpit?

Can it be handled Singlehanded?

Can it be handled by my wife?

Will I use it Religiously?

End of Boom Preventer - Shockles