The standard BRe main sail setup has the tack attached to the boom with a twisted shackle. This works but can be improved to fix the following issues:
- Luff tension can only be set with the main halyard and, realistically, the luff can’t be fully tensioned.
- Because luff tension is set with the main halyard, raising the sail becomes increasingly difficult as it reaches its peak, i.e.as the luff is becoming tensioned.
- The twisted shackle makes “congested” the area at the forward end of the boom and base of the mast track, which adds to the fiddliness of rigging and de-rigging.
The setup can be improved with a cunningham. This is a simple solution that replaces the twisted shackle with an adjustable line. Furthermore, with a 2:1 mechanical advantage the luff can be easily and fully tensioned.
Two vertical holes are drilled and countersunk on each side of the forward end of the boom. There is already a lengthwise hole in the boom for the gooseneck so care is required when drilling. A clamcleat is installed on the underside of the boom just aft of one of the holes. A 6mm line is the fed up through one hole, through the cringle at the sail’s tack and down through the other hole. A knot should be tied in each end of the line to prevent it unexpectedly disappearing through the holes again!
Before raising the main sail the cunningham should be loose. The difference when raising the sail is soon felt because it can now easily be fully raised and there is nothing more than the sail’s weight pulling on the halyard as the sail reaches its full extension. The luff can now be tensioned by pulling down on the end of the cunningham forward of the clamcleat and, when the required tension is achieved, the line is secured in the cleat.
This modification can be fitted by Swallow Boats for those nervous about drilling their boom.