Beneteau First 210 Tech Notes
Title: RIG TUNING GUIDELINES
Author: US Spars
Large books have been written on this subject, but we shall attempt to give you a
concise set of basic guidelines. So here goes.....
The aims of RIG TUNING are as follows:
a. Ensure a straight mast athwartships
b. Control sail shape.
c. Achieve proper helm balance in a variety of conditions
d. Spread loads appropriately on spars, rigging and boat.
RIG TUNING - SINGLE SPREADER FRACTIONAL RIG
(with aft-swept spreaders, permanent backstay(s), no running backstays.
1. Fore and Aft Tune
1.1 Mast Rake
- Mast rake is determined by forestay length. Rake affects helm balance -raking
the mast increases weather helm.
- As a starting point, use the designed rake on the sailplan (ask the boat
designer, not the mastmaker). If no information is available, start at 1:30. (eg 50
cm rake on a 15m mast). To measure rake, tension the backstay approximately
60%, then check rake with a weight attached to the main halyard. (Boat must be
floating level when you do this!). Adjust forestay as necessary to obtain the
1.2 Mast Bend
- Check that the mast is upright athwartships in the boat. Use the main
halyard to measure from the masthead to the chainplate each side. Adjust upper
(cap) shrouds to get identical readings each side (but use minimal tension in the
- A certain amount of pre-set mast bend is desirable, to stabilise the middle
part of the mast and thus minimise rig pump in a seaway.
- Ensure the lower shrouds are slack. Induce the required amount of pre-bend
in the mast by tensioning the backstay. (Make a note of the amount of pre-bend
by using the main halyard tensioned down to the foot of the mast, and
measuring the amount of bend at the spreaders). Tension the cap shrouds
equally, a few turns at a time, until the fore and aft bend starts to increase. Check
that the mast is still straight athwartships.
- Now tighten the lowers in the same manner as the caps, until the fore and
aft bend starts to decrease. At this stage the caps should be tighter than the
- Release the tension in the backstay, check that you are happy with fore
and aft and sideways deflections.
- (Once the rig is set up as described here, tensioning the backstay whilst
sailing will affect the curve in the upper part of the mast only, as the area around
the spreaders is fixed by the opposing forces of the shrouds).
2. Transverse Tune
- Go sailing! Set full sail to windward in smooth water in light winds (10-15
degrees heel to windward).
- Tension the backstay just sufficiently to straighten the forestay.
- If the leeward shrouds are slack, tighten them, but NO MORE THAN TWO
TURNS AT A TIME. Go on the opposite tack and do likewise, then tack again
and check if the lee shrouds are still slack. If so, repeat the operation. DO NOT
OVERTIGHTEN the lee shrouds, as you may bend the boat or break the mast
when you tack!
- Back at the dock, check that the mast is still straight athwartships.
US Spars, Inc provides tuning advice for guidance only and on the understanding
that it is the owner's responsibility to set up his rig in a secure and seamanlike
fashion. WE REGRET THAT WE ARE UNABLE TO RESPOND TO QUESTIONS ABOUT
updated May 12, 2004