GybOmatic Boom Brake

Fleming Boom-Brakes have long been an essential companion for cruisers or circumnavigators on the open ocean. On land today, you wouldn’t think to start your car without buckling up your seatbelt or to purchase a car without an airbag, yet, we still think that getting whacked by the boom is just a part of yachting. Most of us have experienced the boom sweeping the deck in an untimely and brutal manner during gybing [whether deliberately or not] with consequences ranging from expensive – broken boom or mast – to catastrophic – a crew member injured or thrown overboard. This can happen anywhere, on your local bay, not just the open ocean. The all NEW FOR 2011 Fleming GybOmatic resets the standard for Boom Brakes.


The Fleming Boom Brake works on friction provided by wind pressure, causing it to act as a brake, hence its generic name. • It is installed in such a way that it minimizes erratic and dangerous upward or sideways swings of the main sail boom. • It consists of a so-called brake drum, either straight or grooved. • The drum is designed with 2 integral side plates, and the complete unit hangs under the boom.


• A line is run around the drum and fastened on one side. the other lead via a sheave back to the cockpit. • When this line is tightened and the boom moves with the drum, friction at the drum is generated, restricting the boom velocity. • More tension on the control line means more friction and more control on the main sail.

The new Fleming 2011 boom brake is manufactured from marine grade 316 only, no bolts, no aluminum. • It is also line friendly, adopting the tried and tested circular drum weighing in at just over 1kg.

Using flexible dyneema links to connect to the boom. 


Boom Brake, one size fits all up to 65ft @ $425 inc GST.


The Fleming Boom Brake is fitted under the boom, behind a preventer or down haul if they are fitted.

The Boom Brake is best located just behind these devices or no more than 1/3 to ¼ along the boom, away from the mast.

Any number of ways may be selected to fasten the Boom Brake to the boom, from boom vang fitting, under boom slot fitting or even a complete wrap around for loose-footed mains. The side line locations are several but probably best in most installs close to the aft chain plate or attaching to it. Keep as close to the side deck as possible by through bolting or consider Genoa tracks or aluminium toe rails.

Remember the Boom Brake develops tremendous loading, so always check with your rigger if in doubt as to the strength of the selected location.

On many narrow vessels the side attachment will be on the cabin top, which is okay, but substantial strength, must be added to this area. In practice the Boom Brake may rub the cabin top in operation. This can be dealt with in a number of ways after final installation.

In any event, start the install with the Boom Brake directly above the chosen side locations with the boom amidships and lowered to the normal sailing position.

The measurement from the mast to the brake will be the same or close as the measurement from the mast to the side locations. Naturally, this is not always possible, but it is your design install target.

When you have located your best install positions, fasten the Boom Brake to the boom in a temporary fashion. Run a line around the Boom Brake drum down to both side locations and tie off. Swing the Boom Brake through a full ark and note the line tension remains the same or close to same, if not re-adjust the Boom Brake along the boom to suit.

You will note the line always slackens off as the boom moves further out form centre. When you have this working right, fully install the system. In most cases, the portside line will be fully attached and the starboard line passing through a fixed sheaved back to the cockpit for adjustment and cleating off.

Adjustment is done via a cockpit winch. On larger vessels more boom control may be obtained by taking both port and starboard lines back to the cockpit.


1. Locate side deck lugs. Back stay chain plates are best.

2. Start with the brake located directly above the deck lugs, mark boom with texta colour.

3. Measure mast to texta mark and mast to deck lugs. The measurement must be the same or close. If not, move the brake to suit. Fasten the brake with duct tape.

4. Move the boom amidships and lower to centre sailing position.

5. Run a light line around the brake and fasten at deck level both sides.

6. Swing the boom full ark both sides. Ensure the line tension remains the same of close. If not, adjust brake along the boom.

7. Final install the boom brake to suite the vessel.

8. Run lines as per our instructions.


Sailing to windward, the main sail will be well controlled “tensioned down” by the main sheet so the line on the boom brake should be slack.

Coming off the wind when the main sheet is eased, the sail will tend to lift, so tension in the brake line will increase and will need adjustment. Sailing further off wind, more line tension is required to prevent the boom lifting further. Should the sail back wind and the boom gibes, the brake line tension will slow the movement until the boom gets to the point off spilling the wind. If the sail does not move completely over, ease the brake line or momentarily increase mainsheet tension.

Smooth Seas and Safe Sailing.

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