Keelboat news and development: Sigma rig setups?

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Sigma rig setups?

Printed From: Yachts and Yachting Online
Category: Keelboat classes
Forum Name: Keelboat news and development
Forum Discription: All the latest developments for yachts
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=3076
Printed Date: 13 May 25 at 10:07pm
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com

Topic: Sigma rig setups?

Posted By: 3793
Subject: Sigma rig setups?
Date Posted: 12 Jun 07 at 12:28pm

Im trying to get some ideas on setting up a Sigma 36 rig. Its bascially the same as the 38s and I wanted to get some tuning guides for them but you have to be a paid up member of there class assosiation to get them and as I don't own one I don't want to be! I was wondering if anybody has sailed them/ ownes one on here and if so and tips for getting more out of the boat.

Cheers.

Replies:

Posted By: Stefan Lloyd
Date Posted: 12 Jun 07 at 12:49pm

I've sailed S/38s but I'm not going to write an essay on tuning them! Do you have a more specific question?

Posted By: TimC
Date Posted: 12 Jun 07 at 1:26pm

Isn't the sigma 36 rig very different to a 38? In that one is very fractional with runners and the much less so?

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J92s GBR 9224R "Upstart"
twitter.com/upstart_racing

Posted By: Stefan Lloyd
Date Posted: 12 Jun 07 at 2:15pm

Sigma/38 is fractional swept-back rig with runners used to tune forestay tension. It's a lot of years since I sailed a Sigma/36 but from what I remember they are the same.

Posted By: TimC
Date Posted: 12 Jun 07 at 2:21pm

To be honest I've only sailed the 38 so I'm pretty used to its rig but the only 36 we have at our marina is masthead rigged.

A quick google search shows loads of pics of fractional 36s so I guess the one I've seen must have a custom rig on it.

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J92s GBR 9224R "Upstart"
twitter.com/upstart_racing

Posted By: 3793
Date Posted: 12 Jun 07 at 5:18pm

Okay. Sigma 362 is the masthead version the orignal 36 is the fractional version. I've been told to get the caps pretty tight but I have no idea how much rake I want on the rig. Im also intrested in how you use the runners, I know they are for tuning the main and don't support the rig, a friend has a suggested to mark these up, which is great but Im not sure what Im looking for here. I think the main problems are Im used to getting settings off sheets and just going with those and playing aroudn with it. With the Sigma I have no refrences or anything so Im struggling to get started. In previous years the rig has been set up by local riggers but Im unhappy with it now and Im not getting the performance I've seen previously. I think it would be worth my while to sit down and sort it out myself to get better results than they can.

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Posted By: Stefan Lloyd
Date Posted: 12 Jun 07 at 8:07pm

So are you asking about the fractional version? In that case, no the runners aren't for tuning the main. They are for tuning forestay tension (basically more tension = less power but better pointing).

On a masthead boat, runners tune mast bend. Runners on = straight mast, more power, runners off = bent mast. On a fractional rig checkstays do the same thing if you have them, which a Sigma/36 doesn't.

You want the amount of rake that gives the desired amount of weather helm at the target powered-up angle of heel. Which is all very well if you know either of those targets but you probably don't. Around 50cms of rake is likely to be roughly correct (measured by hanging a weight from the main halyard and measuring the horizontal offset at gooseneck level).

When you say "Im not getting the performance I've seen previously" try to be more specific. Slower? In what conditions? Or not pointing? Other reason for going slower are bottom in bad condition, or it's time to write the sailmaker a large cheque.

Posted By: 3793
Date Posted: 13 Jun 07 at 10:29am

Yeah I realised my mistake about the runners! Read a useful book last night! The problem is before we've only really raced her offshore. So we had the chance to sit there and mess about and in a straight line the Sigma is fast and we got some good results. Started really racing her around the can's this year and just can't get the speeds we've seen out of her. On an upwind leg in say 20kts she used to get about 7.4kts and downwind/ broadreaching anyway over 8. She feels really tender on helm screwing up into the wind alot which she never used to do, in gusts she used to be really steady.

As for sails, she has a brand new UK TD Carbon main on her and new set of spinnakers the Genoa all Sobstad gensis. Apart from the No1 which is the hardest used they are all in pretty good condition.

I just can't think of anything diffrent apart from the rig and its my weakest point, I've never really got into learning about setting it up. From sailing One Design dinghys I've always had referance points and people to talk to.

As I was saying the book I've been reading has given me some ideas to try out, I think its just a case of spending as much time as possible trying new things out.

Cheers for any help!

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Posted By: Stefan Lloyd
Date Posted: 13 Jun 07 at 12:07pm

I don't know how well your instruments are calibrated but 7.4 knots upwind, if accurate, is "too fast". For optimum VMG on a boat that size something like 6.5-6.8 would be typical once the boat is powered up. Downwind you aren't likely to get the same speeds inshore because the waves are smaller.

Posted By: 3793
Date Posted: 13 Jun 07 at 12:21pm

At falmouth week last year. We were hitting 7.4 upwind and were holding 8 kts off the wind and getting over 9 at times. The instruments had been califbrated or at least checked over at the begging of 2006.

So what you are saying is 7.4 means we are pointing too low. We need to go for more hight? I.e, increased forestay tension using the runners. The boat dosn't have a VMG meter on it, just wind angle and a couple of displays wind, speed, ect.

Cheers.

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Posted By: Stefan Lloyd
Date Posted: 13 Jun 07 at 1:36pm

I've spent a lot of time helming 38 foot cruiser-racers and target boatspeed in powered up conditions was 6.7-6.8 knots. These are slightly quicker boats than a Sigma/36. So yes, I'd try more forestay tension and more pointing.

Posted By: 3793
Date Posted: 15 Jun 07 at 9:37am

Just incase to follow up. Dried the boat out yesterday scrubbed her off. Put more tension on the caps, worked on using the runners she how high she'd go before the speed really fell off. Got some odd backstay settings from a book using a fair ammount of backastay in the light stuff. Anyway got a 3rd last night, the best results we've had round the cans at are club.

Cheers for the help.

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