Author Topic: Headstay Length  (Read 13243 times)

Justin Scott

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Headstay Length
« on: June 05, 2013, 11:02:13 AM »
Darren Gilbert asked me about my head stay length because I sail with an older pre-Rondar hull. 

I'm not sure what my headstay length is now.  I know that it is a good bit longer than when I first published my measurements for tuning the carbon mast way back in 2008, and I know it is longer than the Rondar or North tuning guides.

This is primarily because I have moved the mast butt back.

I adjust the headstay only once at the beginning of the season to suit whichever set of sails I'm going to use and then I leave it the same in different wind strengths.

I think of headstay length and mast butt position as something to tune in tandem. The objective of headstay/mast butt tune is quite simple. It affects rake and upwind helm balance.

Lengthening headstay+ moving mast butt back reduces lee helm/increases weather helm.
Lengthening the headstay without moving mast butt back, reduces lee helm/increases weather helm and increases rake.

The first priority is to balance the helm. So I take my new (or used) set of sails and go sailing upwind with the rig tuned in all other aspects (consult your friendly sailmakers tuning guide) in medium conditions. I make sure that I have the mainsheet sheeted really hard and the boat flat to 10 degrees of weather heel. I want a neutral helm. Beyond 10 degrees I want a "bite" of weather helm. If I don't have enough weather helm, or if when flat I have sever lee helm. Then I crawl forward and lengthen the headstay.  If I have weather helm when dead flat or too much weather helm when heeled, I crawl forward and shorten the headstay. When it feels right. We sail in, haul the boat and look at rake.

Ideally, it would be much nicer to have someone motoring alongside in a RIB and taking pics (hint hint Barry) of rake but I don't have access to that early in the season. So I do it by eye on dry land.

So far rake has not been a super sensitive tune for me. I have experimented by balancing the helm (Thru adjusting headstay length) with my mast butt in two different positions one hole apart. I didn't notice much difference except that it "played with my head" for a couple of weeks because every marking had to change, mainsheet mark, gnav mark, jib tack length etc.

In 2011 I moved my mast back from the previous two seasons and felt it was better (thus making the mast more vertical). In 2012 I moved it forward (more rake) and felt that was better. As long as I keep feeling better, I guess I should just keep moving it back and forth. No seriously, I seem to have reached a compromise that works.

I feel that as one moves the mast butt back, the mast is closer to standing over the chain plates which means more prebend around the spreaders. But also less protection for the rig downwind.  As one moves the butt fwd, the increased rake seems more like a 5-0-5 set up for big breeze.  BUT really I cant discern much between the two settings I have tried. One is Pepsi and one is Coke. Brad, Ched or Keith might have a more discerning input.

So on land. If the rake looks more than I am used to then I will move the mast butt back. If the rake looks less than I am used to, I move the mast butt fwd. Then I have to go sailing again and retune the headstay as above.       So usually, my crew and I look up at the rake, rub our chins and say "Look good to you?"   "Looks good to me"... and go into the pub for some room temperature beer.

In conclusion. My recommendation for headstay length is to start with the tuning guide length. Then go out and lengthen it/shorten it to get your helm to feel right for you. Every boat, crew and sails combination is slightly different and headstay is the great equalizer for helm balance.  Its the easiest adjustment to tune on the boat.

BUT REMEMBER. Don't do this on race day. This is something that you do on the practice day before the regatta.
1) It will mess your head if you do it on race day
2) Its against the rules to adjust the headstay on race day.

Hope this was helpful. I will discuss insurance in my next post.

 
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Justin Scott

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Re: Headstay Length
« Reply #1 on: June 05, 2013, 11:09:40 AM »
Headstay needs to be slightly longer in the Pre-Rondar boats than Rondar boats.
Remember when tuning headstay, you need to adjust the shrouds and chocks after altering headstay length.
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Jeff Jones

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Re: Headstay Length
« Reply #2 on: June 05, 2013, 01:10:58 PM »
I don't understand this Justin.  I would think the opposite. 

The headstay attachment point is about 3/4" farther BACK on a Bennett which means given the same mast butt position you will need a shorter forestay on a Bennett to get the same rake.

I've found this to be an advantage over the Rondars.  I always like my forestay to be as short as possible - to help reduce sag.  This becomes more important as the breeze builds, so it's good that you are able to reduce rake (shorten the forestay) as the breeze comes up - since weather helm increases.

There is also a class rule that limits headstay length (not rake)...  so on a Bennett you can actually get more rake than you could a rondar.   

I would recommend starting out with max rake - going sailing, and tightening up the headstay length in various conditions until you start loosing that weather feel.  Make notes and that is where you want your headstay length.  (rules also state you can only do it once / day before you leave dock I think, so consider that when choosing for the conditions)

Other things that will affect weather helm and thus how long you want your forestay are

a) rudder angle - old Bennett rudders are more forward swept and it's more difficult to get weather helm.   But Justin likes it because it gives him more control down-wind (he is crash prone)

b) mainsail depth

I've never messed with the base of my mast - but probably should.   I think I measured Brads boat and did the same.  When in doubt, that's probably a good thing to do.


Headstay needs to be slightly longer in the Pre-Rondar boats than Rondar boats.
Remember when tuning headstay, you need to adjust the shrouds and chocks after altering headstay length.
« Last Edit: June 05, 2013, 01:13:08 PM by Jeff Jones »

Darren Gilbert

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Re: Headstay Length
« Reply #3 on: June 05, 2013, 01:32:26 PM »
Jeff, I'm interested to hear what point of reference you measured from when comparing your bast step position vs. Brads?

Do you remember what these measurements were?

Since you've owned a few different Vipers, did you notice much of a difference in this measurement between the boats?
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Jeff Jones

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Re: Headstay Length
« Reply #4 on: June 05, 2013, 02:40:20 PM »
I think I measured from the front of the keel (as it would sit in the down position) to the back of the mast and copied it.  In terms of weather helm, those are the two most important variables - moving either makes a dramatic difference in helm.  So I wanted to make sure I had the difference between the two - the same.

I was also relatively confident that all the keels are in the same place in these boats (from various generations).   It's the only thing I have confidence in being the same.  So that was my starting point.   Sorry, I don't remember what the measurement was Darren, I just make sure it was the same.  My mast base was set and forget.

I really didn't pay any attention to it when I owned 102 or 129.  Sailed as it was set from the factory.   

I was always less concerned about mast base position - far more about that forestay length.  now, had I ever got to the max length point and not had weather helm, I would have then started messing with the base. 

If you have an old rudder i'd recommend looking at getting a new one from Whitecap.  The new rudders not only allow you to shorten your forestay while maintaining the same feel - but they are quite a bit lighter than the old ones.     

Get'em black sheep
 


Jeff, I'm interested to hear what point of reference you measured from when comparing your bast step position vs. Brads?

Do you remember what these measurements were?

Since you've owned a few different Vipers, did you notice much of a difference in this measurement between the boats?

Justin Scott

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Re: Headstay Length
« Reply #5 on: June 06, 2013, 11:22:30 AM »
I don't understand this Justin.

Nothing new there.
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Justin Scott

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Re: Headstay Length
« Reply #6 on: June 06, 2013, 11:26:29 AM »
 

The headstay attachment point is about 3/4" farther BACK on a Bennett

Well there's no accounting for where you attach your fittings when you rebuild your boats. But on everyone else's boats the headstay attachment on the Bennett is marginally forward of the point on the Rondar.

There are Rondars, Bennetts and Jonesys.
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Justin Scott

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Re: Headstay Length
« Reply #7 on: June 06, 2013, 11:41:33 AM »
I always like my forestay to be as short as possible - to help reduce sag.  This becomes more important as the breeze builds, so it's good that you are able to reduce rake (shorten the forestay) as the breeze comes up - since weather helm increases.


The difference of an inch or so will not have much impact on sag. An inch of wire wont add a lot of stretch.  Head stay sag is controlled with rig tension and chocks. Sure, if you shorten your headstay and don't adjust your shrouds, the rig tension will increase.  But you should be adjusting head stay length to tune the balance on your helm, not to control head stay sag.

I like to set up my helm so I feel the right amount of weather helm when I'm heeled about 15  degrees. If I am heeling more than that in big breeze, I prefer to flatten the boat rather than shorten the head stay to counteract weather helm .

In big breeze, conventional wisdom is to put more rake on. This is because (a) You are easing the main in puffs to keep the boat flat and this creates lee helm (as long as boat is kept flat) and (b) I think it is something to do with opening the slot and keeping CofE low.

Jeff has always been opposed to (a) Convention and (b) Wisdom......so naturally Jeff advocates shortening the head stay in breeze.

Now here is a funny thing. I feel the same way. In honking breeze I have this primeval desire for an adjustable headstay on the Viper, so that I can whale on it in monster puffs. But I think its because my gut wants to tighten the rig in puffs and depower the jib rather than because I have got some virus from Jeff.  But, I have been spending too much time with him in the past 3 years, so who knows?
« Last Edit: June 06, 2013, 11:50:50 AM by Justin Scott »
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Jeff Jones

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Re: Headstay Length
« Reply #8 on: June 06, 2013, 12:36:33 PM »
I never touched my forestay fitting. 

Can someone else take a measurement for me.  I'm 99.9% sure the Bennett points are exactly 3/4" farter back than any Rondar I've ever owned. 

I'll do some measure and report back.  If someone else could that would be cool. 


 

The headstay attachment point is about 3/4" farther BACK on a Bennett

Well there's no accounting for where you attach your fittings when you rebuild your boats. But on everyone else's boats the headstay attachment on the Bennett is marginally forward of the point on the Rondar.

There are Rondars, Bennetts and Jonesys.

Darren Gilbert

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Re: Headstay Length
« Reply #9 on: June 06, 2013, 12:45:12 PM »
Jeff - I will be at Chicago Noods this weekend and can measure 29,41,43,55,57 (Rondar Boats), 106 (Rondar UK) and 195 (Rondar USA...I believe).  What is the reference point when doing this measurement?
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Jeff Jones

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Re: Headstay Length
« Reply #10 on: June 06, 2013, 12:47:05 PM »
First, you don't typically ease the main out on a viper during big puffs.  Maybe a few  inches, but not a lot.  When you ease the main your forestay sags - and actually powers up the jib.  When you're sailing in a breeze you keep your main on somewhat hard, and play the jib.   Thus, there is no reason to increase rake in a breeze.     Ease jib - pinch. 

Actually, Brad Boston is the guy who recommended shortening my headstay as the breeze comes on.  But hey, what does that guy know.

My philosophy has always been to a) follow the smartest guy on the course (not necessarily the fastest)   b) take rig tune advice from people who are faster than me c) avoid overturned boats on windy down-hill runs - always listen for Ched's voice telling Justin to get out on the keel).
 



I always like my forestay to be as short as possible - to help reduce sag.  This becomes more important as the breeze builds, so it's good that you are able to reduce rake (shorten the forestay) as the breeze comes up - since weather helm increases.


The difference of an inch or so will not have much impact on sag. An inch of wire wont add a lot of stretch.  Head stay sag is controlled with rig tension and chocks. Sure, if you shorten your headstay and don't adjust your shrouds, the rig tension will increase.  But you should be adjusting head stay length to tune the balance on your helm, not to control head stay sag.

I like to set up my helm so I feel the right amount of weather helm when I'm heeled about 15  degrees. If I am heeling more than that in big breeze, I prefer to flatten the boat rather than shorten the head stay to counteract weather helm .

In big breeze, conventional wisdom is to put more rake on. This is because (a) You are easing the main in puffs to keep the boat flat and this creates lee helm (as long as boat is kept flat) and (b) I think it is something to do with opening the slot and keeping CofE low.

Jeff has always been opposed to (a) Convention and (b) Wisdom......so naturally Jeff advocates shortening the head stay in breeze.

Now here is a funny thing. I feel the same way. In honking breeze I have this primeval desire for an adjustable headstay on the Viper, so that I can whale on it in monster puffs. But I think its because my gut wants to tighten the rig in puffs and depower the jib rather than because I have got some virus from Jeff.  But, I have been spending too much time with him in the past 3 years, so who knows?

Jeff Jones

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Re: Headstay Length
« Reply #11 on: June 06, 2013, 12:50:04 PM »
I don't know Darren, maybe where the bow terminates?  Like that outer lip?   That's a solid point in the tooling and I don't think it's changed since they started building boats.

You might also consider looking at your spreader sweep.   All the heavier teams down here have gone min sweep while the light teams are at max.   The more sweep you have, the stiffer you can make the rig with shroud tension w/o inducing pre-bend.  In other words - if you put the same rig tension on two boats, one is max rake, the other is min rake - the mast with max rake will have substancially more prebend.     

Jeff - I will be at Chicago Noods this weekend and can measure 29,41,43,55,57 (Rondar Boats), 106 (Rondar UK) and 195 (Rondar USA...I believe).  What is the reference point when doing this measurement?
« Last Edit: June 06, 2013, 12:52:45 PM by Jeff Jones »

Darren Gilbert

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Re: Headstay Length
« Reply #12 on: June 06, 2013, 01:02:17 PM »
Thanks Jeff.

I will measure from where the bow terminates to the centre of the hole where the forestay would attach.

I'll try to get as many boats as I can.

Cheers!
Darren
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Jeff Jones

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Re: Headstay Length
« Reply #13 on: June 06, 2013, 01:04:36 PM »
And good luck to ya!  really nice work with the fleet up there, hear ol' 58 might be heading up to play sometime. 

I still have your bunk, by the way

Thanks Jeff.

I will measure from where the bow terminates to the centre of the hole where the forestay would attach.

I'll try to get as many boats as I can.

Cheers!
Darren

Darren Gilbert

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Re: Headstay Length
« Reply #14 on: June 06, 2013, 01:07:38 PM »
Thanks Jeff.  The Great Lakes fleet continues to grow each year.

Can you ship that forward trailer bunk up with #58?  I believe it will be up here for the Sarnia One design regatta.
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