Thoughts on Key West Regatta by Harry Pattison

tweaker

Member
Harry P. I have been racing a bit on a Henderson 30 and I like to trim main. The conditions here in SD are mostly light to Moderate and we don't change the tune of the rig at ALL. I know this is one of our weaknesses. When the wind goes up I know we don't have the rig set up right. I want to take my knowledge and skill level up a notch or two and learn more about the mechanics of rig tune. The first place to start would be to pry a copy of the tuning guide from the owner and start using it. However that just tells you what to do a "starting place" on what to set the rig at for different conditions. What it doesn't do is show me the how and why of the different settings.

I Quote You "By far the most common problem in the fleet was over flattening the mainsail. Boats tended to have too much cap shroud tension and a combination of not enough lower shroud tension and incorrect mast butt location. The result was too much pre-bend and not enough headstay tension. The mains were so flat that any time a puff hit and they eased their sheet the whole sail would luff. The leech would be totally washed out from head to clew and they couldn’t point. The good boats were set up so that they could board out the top half of the sail, but still kept some depth in the bottom half. When they eased in the puffs the top would twist more and the upper leech would go out, but the lower leech always stood up. It is also the combination of cap and lower shroud tension that control headstay tension. Not having the mast stiff enough let the headstay sag too much which resulted in the leading edge of the jib sagging to leeward and rotating the sail around the leech. The result was either a leech that hooked back into the main or sailing with the jib sheet eased. Either way the vertical profile of the jib was nowhere near straight enough. In a boat with swept aft shrouds and one size jib, rig tune is king. The top boats were adjusting between every race and had pages of recorded settings for different conditions. The best way to I’ve seen to accurately set up the rig is to use an inexpensive plastic dial caliper to measure the distance between the studs in your turnbuckles. This seems to be much more accurate than using a Loos gauge."

In the quote above I understand why the "bad" set up is bad and why the "good' set up is good.

My question is where can I find more info on the "Mechanics" of rig tune, on different rigs and the relationship between the different parts and the effects of the differing settings on sail shape?

Or can You be more specific on what changing the mast butt, cap shroud, etc settings do to rig and sail shape? I already know most of the basics for a MH rig and less for Fractional rigs.

In the example quoted above I am guessing that tightening the lower shrouds would straighten the bottom section of mast making the lower portion of the main fuller and not as flat. Do they also help to tighen the Headstay? Some how the position of the mast butt effects the mast geometry also. Where does this come into play?

Jump in if you know the answers, these question are not just for HP.

 

Blackadder

Member
477
13
San Diego
Tweaks, You are asking a lot of questions at once, but what you need to do is to sit back and think about what you need the sails to do in various conditions.

Fast Twitch should be a smokin boat, she's got a ton of sail and is pretty light. She looks like she's always suffered when the breeze gets over 8. What HP and Mark Washeim were talking about was balancing the rig tune with the desired effect on sails. Its a fact that with very tweaky boats there is no one size fits all, you probably got to vary the settings.

Assuming you have a big arse roach main most of your problems are associated witrh depowering so that you don't lose point. If your rig is too loose you will have too much sag in the headstay and won't depower effectively. If you set the rig tensions up evenly its a lot easier to depower and not overdo the mast bend.

But hey its SD there's not a lot of wind anyway! There are a lot of ways to do this and get it right for the boat.

D

 
Rig tune is way too big an issue to answer in one or two posts. And it is quite different depending on what type of rig you have. I'll try and put together something that will at least cover J105 type rigs (fractional, swept aft shrouds, small jibs) in the next week or two and maybe Scott will post it.

 

cheapshacht

Super Anarchist
1,834
0
Alexandria, VA
Looking forward to it. Do one on masthead inline spreaders and shrouds if ya have time.
Excellent idea! Harry, I second that motion. Tackling this case will probably help more people on the forum than the J105. ( :eek: flame away ...)

 

JimB

Member
How about a 15/16 rig with double in-line spreaders and checkstays. Maybe its actually 7/8. Anyway it is a lot closer to being a masthead than a frac. Thanks for your thoughts so far Harry.

 

mark washeim

Member
199
5
Oh, Harry,
Look what you got yourself into..
Don't laugh, I may be calling you to help out.
it's so funny that you say that because i was thinking of offering. i'll send you a BIG email & you may take what you like from it or ask me to screw it around a bit.

 

tweaker

Member
Rig tune is way too big an issue to answer in one or two posts. And it is quite different depending on what type of rig you have. I'll try and put together something that will at least cover J105 type rigs (fractional, swept aft shrouds, small jibs) in the next week or two and maybe Scott will post it.
HP what ever you can do will be great. I know I asked a lot of questions, but I was thinking there might be a book/s available that cover this topic also. I guess not. This type of thing (rig tune) is like the "dark arts" of sailing only sail makers and top level sailors seem to know this info. It seems like you have to aprentice with the Master to learn stuff like this.

A J105 type rig example would be perfect as I sail on those too.

The Hendo rig is simular except is has the runners and will carry over-laping head sails at times. We have been using the runners effectively at times to change headstay sag to power up and down the jib in puffy conditions.

If you Masters have the time to enlighten us aprentice tweaker thanks you.

 

tweaker

Member
"Fast Twitch should be a smokin boat, she's got a ton of sail and is pretty light. She looks like she's always suffered when the breeze gets over 8. What HP and Mark Washeim were talking about was balancing the rig tune with the desired effect on sails. Its a fact that with very tweaky boats there is no one size fits all, you probably got to vary the settings. "

Blackadder I agree with your last two statements in the quote above. We have got to vary our settings. I know that tightening the backstay bends the mast and flattens the mainsail, etc. my questions are looking for more mechanical relationships between all the differnt parts . How the mast butt comes into play? and the changes to that that affect the other pieces, etc.

Like most boats "Fast Twitch" has other issues than rig tune and sail trim that effect our performance. We are always sailing short handed and this directly effects our up-wind speed. 2-5 people aren't enough when the wind is over 8. Having more crew and getting the rig right will help.

FT is a kick ass boat and I am having a blast sailing on her. The bummer is that the owner is putting her up for sail.

 

Blackadder

Member
477
13
San Diego
Hey Tweaker, if FT is going away, come over to the dark side we can discuss rig settings all day long!! the J/27 is a notoriously tweaky rig boat and changes dramatically depending on how you set it up. We can be real sloooww, or quick.

The mast butt position changes the prebend in the stick assuming you keep the shroud tensions the same. Further aft = more bend, further forward = less bend. If you have swept back spreaders the backstay will bend the stick and will add some tension to the headstay, which both flattens the main and depowers the jib. This is more effective if the lowers and uppers are more even in tension. The runners though will have much more effect on the h/s than the backstay.

Didn't you guys win your class in Sugarloaf this weekend? Congrats!

We watched DC tangle (literally) with a commercial fishing set up, all kinds of excitement on that boat.

 

tweaker

Member
BA thanks for the congrats.

I was wondering why DC DNF'd. We had a near run in with some com/fishing boat backing down on the nets. We hard time figuring out what it was doing and where it was going.

They musta been catchin the Giant Squid.

 

Craic

Super Anarchist
1,223
0
San Diego, CA
Glad to see this thread and the willingness of Harry and Mark to lend some knowledge to us hackers.

Harry, how about one for a no backstay, no runner, stiff carbon stick, fractional rig like the ones you'll be making the sails for very soon. Ya know the worst marketing awardee. :D Definately gonna need some tuning guides on this one!

 
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