Boom Brake attached to boom at 48” back from gooseneck using length of 1/8” AmSteel-Blue Dyneema AS-78 single braid. Attachment was made by square lashing the line around boom (main is loose footed) through top eye of boom brake and finished with a rolling hitch around lashing between Boom and Brake. Another option that is bullet proof in preventing any boom damage is to rig it to a line that extends between either end of the boom. Another option is to attach it to the center of a line that is attached to the boom in 2 places preferably spaced apart at least 1/3 as long as the boom. In other words the load is spread across 2 attach points to the boom and not a single point.
The most common setup is to run the friction line up through, around and back down through the Brake as in the image below.
Use our online app here to optimize the brake and anchor point installation positions.
The calculator optimizes the location on boom or anchor points based on minimizing friction line length delta or change that would be required to swing from center to biggest angle of boom swing you want.
See the graph at the bottom of the app that shows the line length required at each angle of boom swing.
This needs to be minimized preferably to under 2" which is provided by the swing in the brake and any slop in system. Much above that could jam the friction line as the line length cannot change so the boom could stop suddenly, potentially damaging boom or other gear. In an ideal 2 d world the brake would swing a perfect arc between the anchor points but these calculations must consider the 3d which is a bit more complicated.
Moving the brake aft compromises the maximum swing angle possible. The maximum point of swing is approximately at where the brake goes outbound of the anchor points relative to the center line of the vessel..
Always test with approx. 10mm or 3/8" friction line. You should be able to swing the boom with some effort by hand.
Hope this helps.
After several trials using different diameter line, the final Tension Line was determined to be New England Rope, 3/8”Sta-Set, Polyester Double Braid. Length will vary with the vessel. Attach a Ronstan, Standard 2 11/16” S-Bail Snap Shackle to the working end of the line using a Buntline Hitch, Fisherman’s Bend or Bowline. Attach point of shackle according to what is suggested in directions, our point is the Port lower after stay turnbuckle. (We do however recommend a dedicated U bolt or pad eye with a strong backing plate be installed in the deck and not to use the turn buckle - Ed)
In order to adjust the tension of the line a block and tackle was constructed that could be actuated from the cockpit. The running end of the Tension Line affixed to the swivel of a Ronstan, Series 40, All Purpose Fiddle Block. Construct the Double Tackle using New England Rope, 5/16” Sta-Set, Polyester Double Braid. (3850 Lb breaking strength) eye attached to a Ronstan, Series 40, Fiddle/Becket/Cam so control line leads back to vessel cockpit. Attach another Ronstan, 2 11/16” Standard S-Bail Snap Shackle to the Fiddle/Becket/Cam swivel. Attach this Snap Shackle according to what is suggested in directions, our point is the Starboard lower after stay turnbuckle.
Parts List:
Samson, 1/8” AmSteel-Blue Dyneema AS-78, single braid (2,500 Lb Breaking Strength)
New England Rope, 3/8” Sta-Set, Polyester Double Braid (5,100 Lb breaking strength)
New England Rope, 5/16” Sta-Set, Polyester Double Braid (3,850 Lb breaking strength)
1 Ronstan, Series 40, All Purpose Fiddle Block (882 Lb breaking strength), Part # RF41500
1 Ronstan, Series 40, Fiddle/Becket/Cam (882 Lb breaking Strength), Part # RF41530
2 Ronstan, Standard 2 11/16” S-Bail Snap Shackle (1,870 Lb working load), Part # RF6110
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