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

Can anyone tell me how to properly rig the mast for racing (rig tension, rake, etc.)? We bought the boat used with a mix of sails and we don't have a sailmaker that is familiar with the J-30.

I would follow the Banks Tuning guid.
http://www.j30.org/html/technical/tuning_guide.html

Be prepared for a ton of pressure on the shrouds. They are like a piano but it works. If you sail in light air maybe back them off a bit.

I also have the UK tuning guid off the jboat site before it became unavailable.

I can email that to you.

David,
#397

Pay attention to all components of the tuning guide. I sailed with my mast butt 3/4" too far aft for a couple of years, and I could never get the rig to set up right (way too much prebend).

Mast butt max forward, headstay class max, THEN start setting tension according to the guides.

I have North sails, and generally err on the light side of tuning ranges. We go pretty floppy in light stuff-seems to be fast.

Steve, you'll be amused to know that too little pre-bend is just as fatal to decent tune.

- David

In my opinion unless it blows where you are 44-46 is too tight. We only go that high in 20+. Base tune on our boat is 40-42 for 8-10 knots. I always tighten lowers first uppers next and loosen upper first lowers next to minimize excess pre-bend. John White sailed his J/30 with much looser shrouds and a headstay tighter than max. Tune varies by mainsail shape which depends on make and age.

I'm confused about "headstay class max". When I installed roller furling with a new headstay, I carefully measured and pre-set the headstay to the max. spec. This resulted in a lot of mast bend, a very loose backstay, and a lot of headstay sag in a breeze. I've now shortened the headstay an inch or so and still have lots of mast bend. How much tension is assumed when doing the class measurement for headstay length?

A follow-up question about Loos gauges. CAN-106 came to me with two: Model "PT-2" and "Model B". When the tuning guides refer to "the new style Loos gauge"....which is it?

-Corey

You can convert Loos Gauge measurements from the various types using the chart on the Loos web site. See this link, then scroll down near the bottom: http://www.loosnaples.com/howto/ptgauges.htm

PT-2 is the best. It just hangs on the shroud while you adjust.

You can follow the pounds of pressure vs the number. That is how to convert.

David
#397

According to the Banks guide, the uppers are 44-45 and the lowers are 45-46. I'm prepared for a "ton" of pressure but did you really mean 2000lbs?

On the Loos model "PT-2", the gauge maxes-out at 40 (2000lbs) and the model "B" maxes-out at 43 (1800lbs) for 1/4" shrouds.

The Loos guide suggests that the breaking strength of 1/4" stainless is 8200 lbs and that a starting tension for the forestay on a fractional rig is 15% of breaking strength or 1230lbs. The starting tension of the shrouds on a fractional rig with swept-back spreaders is 20% or 1640lbs.

Can someone comment on shroud tension in lbs instead of loose Loos #'s?