J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Main sheet

Hey everyone. Velocity Girl is shaping up great so far. I am trying to clean up the cockpit a bit and I am trying to limit the rats nest of lines in the pit when I am racing. Does anyone have a ballpark length on the main sheet. I also have adjustable jib cars and the line seems too thick. Any suggestions on sizes or lengths? Thanks for any info.

HHSA
Velocity Girl 278

I replaced the main sheet with 75 feet and it works fine.

The best way is to go with a fine tune system. This cuts the main sheet down by about half the length since the main is 4:1 vs 6:1 and the block to block distance is reduced by about 4 inches.

However the biggest advantage is perfect control of main sail shape in all wind ranges, my wife can easily trim in 20+ and tacks are faster.

David
#397

Having David trounce me at the Marblehead NOOD was a good demonstration of this setup. David - can you post the part numbers for the blocks you used on this setup?

Tnx - Bill

Hi Bill,

Here is are some photos of my setup:





The top Double is a Harken 2602
The middle Double is a Harken 2638
The bottom ratchet is the Harken 170 Hexa-Cat (standard J/30 mainsheet)
The triple is Harken 196 Low Profile Triple with Cam & Becket

I measured the fine tune so that when we are hard on the wind the small double is just belown the top double when the top telltail is just streaming 100% of the time (powered up mode). This gives me plenty of adjustment to get the leach right where I want it. Once I measured it, I cut it and put a ball on the end so we can just blow it on tacks and it stops in powered up mode and then all we do is just re-trim after a tack with the fine tune.

Hope this helps.

David
#397

David - great photos. Thanks for the info.

Bill

After much experimentation we settled on a setup nearly identical to David's except we kept the original triple on the boom. This allows two alternatives: 4:1 gross/4:1 fine or 6:1/2:1. We tend to use the first in light air and the second in heavy, though I'll admit to laziness in changing from one to the other unless the conditions are extreme in either direction.

This might seem counterintuitive since the first has more power (16:1 vs12: 1) but there are other considerations. The real advantage of a 4:1 primary is in light air downwind when the line eases freely and can be trimmed rapidly. Despite being more powerful for heavy air, the 4:1/4:1 setup creates an unbalanced load on the triple block. In the second photo above, the left sheave carries the primary sheet, taking more load (4x??) than the two sheaves carrying the fine tune. In 25-30 knots where mainsheet loads are 600-900lb, this can exert enough torque to bind or deform the triple block.

There's also the issue of dumping the mainsheet. When a puff hits or you have to execute a duck it can be difficult to uncleat a fully loaded 4:1 coarse tune line and slow to have to ease the fine tune first.

Bear in mind two part mainsheets also have a propensity to tangle, requiring better cockpit housekeeping. We find it best if both cam cleats face in the same direction, as shown. It helps to drop the bitter end of primary mainsheet into the cockpit locker so it can't get knotted. Use a minimum length fine tune and be sure to use a different color line.

Bob,

We have sailed only in about 25kts so far with the setup and have not had any issues other than the top block does not like to rotate on tacks and as you said you have to be diligent about keeping the blocks in column and pointing aft of the traveller.

However to get around the speed issue of dumping the fine tune I cut the sheet down to the correct length and added the ball at the end. Now all you have to do is quickly uncleat the finetune and let go of it and it zips to the bitter end and once it has been uncleated and eased a bit the load comes off and then you can uncleat the main. It also gets the line out of the cockpit. In light air we do not use the fine tune so it does not add to the rats nest since it is cut down.

I built this setup from the info you gave me and it has made an amazing differnce in our abilility to trim the main.

Thanks,
DB

Thanks guys... the advice has been great. We just completed out first Distance race here on lake Ontario and we took second to a Geiger 35 but managed to beat a J29 a J35 a Goman Express 30, and a C&C 35 Mark III. So it was a good race. The help I have been getting on the forum has been great!

I love the pics and I am looking on Ebay for some bits and pieces to complete the upgrade.

HHSA
Velocity Girl

David - I'm finally getting around to the fine tune setup on my winter work list. Question on what you have for line on the fine tune. It looks like 3/8" - what size and type did you use there? Tnx - Bill

ps - call me when you get a chance on some planning for next summer.