J/30 Class Association Forums J/30 Forum Racing Tools and Techniques Mast Set Up/Rig Tension

Different guides say different tensions.

From the Shore Sails Tuning Guide
Light Heavy
Uppers 1700 2000
Lowers 1300 1800

From UK Tuning Guide:
6. Tension the uppers and lowers gradually and evenly (counting turns as you go), until there are approximately 1800 lbs. On each, as measured with a Loos tension gauge. Start with the uppers, adding just enough tension on the lowers to keep the mast in column as the uppers get tight. Put final tension on the uppers with backstay fully on. Release backstay, and put final tension on the lowers. As you tension the lowers the pre-bend will be reduced (they pull back on the center of the mast). Tighten until pre-bend is no more than 2-3".

7. Upper and lower tension should now be close to even. This should leave you with about 2" of pre-bend (it probably looks like more, but you can measure it by putting the mainsail halyard against the back side of the mast, and subtracting 2" from what you see). Tighten the lowers to reduce pre-bend (make mainsail fuller), let off to increase, (flatten mainsail). Conditions and mainsail shape will dictate the correct amount of pre-bend.

Simply stated, the tighter the overall rig tension, the greater the headstay tension; as long as the tension is nearly equal on uppers and lowers. In lighter air, when more sag is desirable, ease both shrouds slightly, and ease the lower shrouds more than the uppers to allow for more pre-bend. In heavier air, use more tension (2000 lbs) on both; the lowers should be as tight or tighter than the uppers to reduce pre-bend.

From Banks Sails Tuning Guide
Uppers: 44 - 45 on the Loos Tension Gauge.
Lowers: 45 - 46
***Note: These are Loos Model B numbers. Using the chart at this link with conversion from Model B to PT-2 gauge (Numbers Extrapolated linearly at end of chart for PT-2 values on scale greater than 40): http://www.loosnaples.com/how-to-use-pt-series-tension-gauges
Uppers: 44 - 45 Model B
Uppers: 41 - 42 PT-2 (Off-Scale)
Lowers: 45 - 46 Model B
Lowers: 42 - 43 PT-2 (Off-Scale)

Echoing Bob Rutsch's comments - the Banks Sail tensions listed are too tight in my opinion, and if done this way tension the rig greater than 2000 psi. Bob's suggestion for 8-10 kts wind has readings of 40-42 on the Loos Model B that equate to 36-39 on Loos PT-2 which is 1100-1600 psi

[This message has been edited by whk (edited 05-09-2007).]