49erFX Tuning Guide and guidance

[Rambler]

If your skiff rig is at 100% tune (in the18 or the 49r) in the puff, the mainsheet should not ease:

See forestay stability. com etc

There is some footage from the last Giltinan of the Kiwi winners, mainsheet immovable at top range big sail...

Hi Frogman (or can I call you froggy)

Google search of "forestay stability..." didn't produce anything for me.

I like to learn. If there are other good materials, could you attach links please.

I can't say our 15's are at anything like that level. But then we have a single rig across all wind ranges - mind you, so do the 49ers, so can't use that as an excuse.

 

[Frogman56]

Rambler,

Oops... 

1. Forestay stabilty .com was a little joke. Reality tho, is that somewhere around 40% of the headstay load comes from the mainsheet... depending on lots of factors, to be sure.

2. The mains in the pics you sent are on the deep side. I do have some ok 18 pics at least and will dig one out and post in the next few days.

3. Froggy is a nicer label than most people use

,

 

[Rambler]

Rambler,

Oops... 

1. Forestay stabilty .com was a little joke. Reality tho, is that somewhere around 40% of the headstay load comes from the mainsheet... depending on lots of factors, to be sure.

2. The mains in the pics you sent are on the deep side. I do have some ok 18 pics at least and will dig one out and post in the next few days.

3. Froggy is a nicer label than most people use

,

Oh dear. I'm a bit of a literalist. Make whatever conclusions you want from that.

It is interesting studying the photos. Its why I included them.

Easy enough to pick the 'this should have been tighter' problems from them afterwards. Harder to judge on the water but just studying the photos helps make you think about it next time.

And getting downhaul and cunno adjustments right are one thing. Getting the rig tension right for each day (not adjustable on the water) is a whole nother and I don't think we're anything close to really working that through..

 

[Rambler]

Interesting fact.

Each of the forward hands on the above boats is a female, between 25 and 40yo, who for all practical purposes, had never set foot on a sail boat before 2 years ago.

All are graduates of our training group. The boats were not designed for women; indeed, they're a bit light. Its just how the group has panned out.

The skipper of 09 is a woman who's just come back to sailing after a 20 year absence, although not previously in skiffs; again after a bit of a refresher and update in the training group

 

[G-Shack]

 


But in essence the 1st batten is the trigger batten, by altering its stiffness and it's bend profile you can get the leach to stand up, with camber, stand up with very little camber or invert and de-power.        The other big factor is the rocking of the top panels to exploit the bias and wrap & weft.        

The 2nd batten is the camber batten and it sets up the top ½ of the sail.   The other battens, their bend profile is important but otherwise come along for the ride.

In terms of stiffness, 1st is say X-kgs, 2nd is 70% and the rest are 20-30%.   

Firstly thanks for taking the time to talk about this. I'm a bit late to the forum. I've heard you mention the trigger point on the batten many times before but this is the best description you have given that I have seen. I have a couple of things which it would be great if you can confirm. 

1. I assume by stiffness you are talking kg/m (SI units) not batten manufacturers stiffness rating? So if batten 2 is 30% longer than batten 1 it is effectively 30% more flexible for a given batten section?  
   
2. To stand up with camber a stiffer batten with more tension is required?
   
3. To stand up with little camber a stiff batten with less tension is required? 
   
4. A softer batten will invert more easily? 
   
5. What are your thoughts on the interaction between cunningham and cap shroud tension and the trigger point of batten 1? 
   
   
   My thinking is depending on headboard length it  may be preferable to allow the batten to invert at a given point but then keep caps tight or run a stiffer batten and allow tip to drop to leeward 
   
6. I'd be really interested to know your thoughts on this from the perspective of a heavier or lighter than average crew and how you could tweak the variables. 
   

If you could sum this all up in a few lines that would be appreciated  :lol: (That bit's a joke) 

 

[MPH]

I forgot about my Tasar question last year! Julian, at your leisure would you mind back-peddling and revisiting the design of the Tasar and its rig?

 

[JulianB]

Firstly thanks for taking the time to talk about this. I'm a bit late to the forum. I've heard you mention the trigger point on the batten many times before but this is the best description you have given that I have seen. I have a couple of things which it would be great if you can confirm. 

1. I assume by stiffness you are talking kg/m (SI units) not batten manufacturers stiffness rating? So if batten 2 is 30% longer than batten 1 it is effectively 30% more flexible for a given batten section?  
   
2. To stand up with camber a stiffer batten with more tension is required?
   
3. To stand up with little camber a stiff batten with less tension is required? 
   
4. A softer batten will invert more easily? 
   
5. What are your thoughts on the interaction between cunningham and cap shroud tension and the trigger point of batten 1? 
   
   
   My thinking is depending on headboard length it  may be preferable to allow the batten to invert at a given point but then keep caps tight or run a stiffer batten and allow tip to drop to leeward 
   
6. I'd be really interested to know your thoughts on this from the perspective of a heavier or lighter than average crew and how you could tweak the variables. 
   

If you could sum this all up in a few lines that would be appreciated  :lol: (That bit's a joke) 

WRT 1. The way I measure battens is to have them vertical, with the tip on the floor, put a spring balance on the other end and pull slowly down while watch the gague rise.   At a point (the Euler Crippling Load) the number will cease rising as the batten bends further and further., so you then back off, lift the scale until it just starts to fall (the reading), back and forward a few times until you find the sweat spot.     In China when they do this, when they find the sweet spot, they are doing this up against a wall with paper on it and they trace the curve of the batten.     When I do it, I have a camera set up and a remote, then I snap a photo.  

The number of the scale, the tension when its at the sweet sport, it could be 4.25kgs and the shape of the curve, we normall define that by % camber and % placment of max camber define the batten.     Then you need to make some statments WRT straight aft run, or heavy fwd curve.   My photo system, I then scan the photo into Rhino (3d program I use) and that defines all of that.

WRT 2. Ostensibly YES

WRT 3. Correct

WRT 4, Absoutly

5. holy shit, what a can of worms!    Give me a few hours.    It's more of a queastion of how to explain it, rather than what to explain.

                       jB

 

[G-Shack]

Thanks for the response. Good method for the stiffness. I guess I could also push down on a set of weighing scales and get the same measurement. 

I need to think about how the camber at the sweet spot relates to the sail camber but I will await your thoughts on question 5 as I suspect it's going to be pretty interesting. 

 

[JulianB]

Yes, putting the tip of the batten on a good set of scales works very well also.

When we started doing this, which was in the early 80's, digital kitchen scaless did not exist, and my father was a man of consistancy, so we probably used a very old set of fishing scales, very likely in Lbs untill well into the 2000's.

But now with these really good kitchen scales going up to 7 - 10 kgs, it works well.

         jB

 

[JulianB]

What are your thoughts on the interaction between cunningham and cap shroud tension and the trigger point of batten 1? 

1. My thinking is depending on headboard length it  may be preferable to allow the batten to invert at a given point but then keep caps tight or run a stiffer batten and allow tip to drop to leeward 
   
2. I'd be really interested to know your thoughts on this from the perspective of a heavier or lighter than average crew and how you could tweak the variables. 
   

Downhaul tension is a primary trigger/control WRT the #1 batten, Cap shroud tension or lack of it is a very secondary control.

Pretty interestingly, we are presently knee deep in sail re-evaluation WRT the 49er and the FX, Jimmy, one of the skippers trailing the sails here in Sydney, he is well aware of the loose Caps WRT the FX to get it to flick off, and given that all the sails are now "more firm" giving the upping of the structural components, he is looking at using "more stretchy" dynema, so SK78 rather than SK99 to possibly breath some life into the otherwise "more firm" sails.   (this is WRT the 49er, not the FX)

Not sure it will work because the actual amount of load in Caps is quite small on a boat like the 49er.   So you may need to go to VBcord to get the desired result.

Tops of sails inverting when over pressed is common and not slow, one of my favorited 18teen photos is a 1991 shot of AAMI with the top 1/3 of the front of the main inverted (pin head)  and at the time of the shot, we where "hauling arse" under a bigger more favoured competitor who we completely hosed in 300-400m.

Tops of windsurfers and 49er flicking off to leeward works.

As I have said before, we are still in very un-chartered territory with Square heads, but the really big (as in long) head-boards so FX style require much stiffer and therefore heavier top-masts and corresponding top batten than there more moderate counterparts.

Very much as a matter of 1st principals, because it’s longer, (the #1 batten) it has to be stiffer and therefor heavier.

We are making the headboard on the 49er a little bigger to get some more flick, but a little is 50mm, still way under the size of the FX, and the real joy (also the draw back) of the 49er and the FX is the level of detail that happens and the on-going evolution in just the way they sail them and the extent to which teams develop completely different solution to similar problems.    The loose cap shrouds is but one, possibly VBcord caps may be another, it’s a lot of fun watching it all happen.

WRT weight variations, the biggest level you have, when you playing like we are now, is mast stiffness, so the amount of bend/curve and the resulting possition of the curve.    Finally the fairness of the curve.

Back in the late 80's and into the early 90s with pin-heads, we got very thingy about rates of bend and matching that to the size and rates of curves in the leach/roach.

But watching the way that these crews play with rig-tensions to set the boat up for their scenerio, so weight/height and therefor leverage/RM is fasinating, bit less horsepower but also less drag, provided you alter your rig to accomodate that seems pretty clever, and it would also appear to allow a wide range of body heights/weights to have very equal performance.

There are strengths and weaknesses in every crew, its just about playing to your strengths and trying to avoid the weaknesses.

~~~~~~~~~~~~~~~~~~~

Tasars will have to wait a bit longer, sorry. 

 

[Board skiff]

Interesting sail choice for the 49er and FX. 
https://www.yachtsandyachting.com/news/236255/49er-and-49erFX-sail-to-North-Sails-3Di

 

[Daniel Holman]

Blimey its not even April! 3Di are approaching double the cost of panelled in most classes, and you generally don't even see the NS jockeys use them in most classes where you have choice. Moth and 18ft perhaps being exception. I wonder how they made the calculations re: longeivety?

Windows in 49er pics look big!

 

[JulianB]

If you buy a one off 3Di sail, it's expensive, as it should be, one off setup, design, etc etc etc.

Start buying 50-100 at a time, same set up & design cost, but only once, so they end up very cost effective.

The biggest thing the sailors wanted was consistency, and 3Di and it's moulds potentially offer that better than any other process.   

Equally weighted to Consistency was Vision.    49er sailors like to be able to see.

4th was Longevity, I think all the candidates offer Mains and Jibs that would last longer and yes we asked lots of questions, particularly of Moths (WRT 3Di) as they are similar loadings and those we asked said things like "tapes wear out before the laminate, and they are good tapes", or "you can use the one sail all year".

6th was Price, the attitude was pay ½ as much again for a sail that last 2 - 3times longer, your way ahead, not just in cost.   The reality we won’t even be paying 1 ¼ x's!     

Buy a one off 3Di sail, yep it's expensive, because one-off design, one-off mould set up, one off disposables.  

Buy 50-100 at a time, and factor in Consistency and Longevity, and your way ahead of the curve on so many fronts.

Add that to the new mast, that is cheaper and more consistent also, it’s all win-win.

Some really big names tested the sails, over saw the testing, or were part of the evaluation team, and bar JC and I abstaining (as we must) it was a unanimous decision.

The other really big winner is the environment, and that is a multiplier on so many fronts.    3rd less sails, less disposables, less wastage, less energy and less logistics.

But most importantly, less hassle!!

 

[Wright Way]

Start buying 50-100 at a time, same set up & design cost, but only once, so they end up very cost effective.

So explain why class sails in nearly every dinghy class I have come across are about 3 times the price a local sail maker can do them for. 

 

[JulianB]

BOI guy

I am getting rather sick and tired of this.

If you want to play the SMOD game, you play by the people who sail those classes rules!

I think there are 150-180 WS Int classes, there are about 20-30 of those that are SMOD which in all but the case of the RS boats are really MMOD's. [Multi Manufacture One Design]

I don't know the number, but I would guess that 4-5 of the MMOD's account for more than 50% of boats sold in terms of $$$ per year.   (excluding big yachts, obviously)

So a very large proportion of the worlds sailing population chose to play the MMOD game.  And if you took out IODA which is closer to a MMOD than it is to an Open One-design then that number becomes overwhelming.

If you do that maths, there are lets say, 120 - 150 Int class that allow you to go down to your local sailmaker and buy a sail from them.     So if you don’t want to play the MMOD game, you don’t have to.

But if you want to play the MMOD game, then you need to play by everyone else’s rules, you can’t cherry pick and expect anyone else to respect you in the morning.

Shortly after the AKL/Geelong AMG’s of the 49er class some really impressive sailors formed a group to help select a sail manufacture, and one of the first jobs was assigning a weighting to what was important WRT that process.

Equal #1 was Consistency and Vision as already been stated. And weighted 100%

#4 was Longevity weight 50%

#6 was Cost weight 10%

That is the weighting, derived by those sailors based on the wishes of the people at those AGM’s  (AKL and Geelong) as to what they deemed important.

The cost of doing Consistency was probably 8%.

The cost of doing Vision is probably 4% & the

Cost of doing Longevity, up around 12%  (this was common across all sailmakers)

I do remember a Paul Elvstrom quote as being something like “you have only won if the guy you beat thinks you won”.  

Probably sums up the attitude of the 49er/FX, likely 29er, ILCA and most MMOD sailors.

If you want to play that game, you play by their rules, not by you’re rules.

If you want to go get local sailmakers and play another game, there are another 150 Int classes and possibly 10 times that number of regional classes to enjoy.

If you want me to go into the pros & cons of Single Source sail-making vs open sail making, I can do that, we have done those tests every 4 years for the last 20 years but that is a completely different debate.

But the 49er/FX sailor have made it abundantly clear that want to play the Single source sail making game, you got to remember it’s 18 months ago now, but I think the quote was “more of the same, just more consistent, they should last longer and if they cost a bit more, so be it!”

The person who said that, and in doing so summed up the assembled multitude, virtually unanimously, dissenters would have been less than hand full, ended up on the selection group, and has been true to their word.

 

[Daniel Holman]

So basically this comes down to "purchasing power" and discounting, which is all good capitalism.

If the 49er class members want to pay 25% more (assuming it is only 25% more?) for something that they believe lasts twice as long (how that is concluisvely proven I don't know) then that absolutely makes sense - and probably is indicative of the fact that the vast amount of 49er sailing is done by olympians and olympic wannabes who will burn through a few sets of sails a year, rather that weekend warriors.

I must admit that, in all areas of business that I've been involved in, making stakeholders buy in to even subtly higher first costs even when proven to have lower through life cost (even when savings are in millions) is a very very hard sell - some of that is pure stinginess, some of that is short termism, some of that is attributable to the cost of capital. Cost of capital and opportunity cost at least is calculable.

Is there evidence of inconsistency of the panneled sails? They will all be laser cut out in big batches, and the likelihood of errors / variation in sticking of seams accruing over entire sails in a way to cause measurable inconsistency doesn't add up for me. Humans sticking seams is a stochastic process.  Which leaves material - the cloth and laminate is presumably QC tested leaving cloth manufacturer and possibly even by sailmaker - is there typically a large variation in mechanical property seen there batch to batch? I think I owned 20 or 30 laser sails over 10 years and I couldn't tell any difference between sails when new, apart from that they all got knackered quickly.

Is there some wider play here by NS to get more 3di adopted in smaller classes? Its pretty widespread in raceboats > 30 or 40ft. I kind of doubt it as I get the impression that outside of SMOD, most dinghy stuff is nuisance custom to a company big enough to have shareholders etc. 

So the thing that is interesting to me here is that a 3di North in most dinghy classes is approximately double the cost of panelled.

I just struggle to see how 3di or 3dl before it is a more consistent or scaleable tech than panelled - its not like they can suddenly make 20 sails in one hit like an injection moulding. The sail still needs pockets and corners and tabling by a human being. Equivalent economies of scale exist in panneled sails esp for SMODs.

So if the SMOD 3di is "only" 25% more expensive than an (already heavily value engineered) panneled sail, this implies that the near 100% markup in non SMOD is made up to a large extent by profiteering and differentiation. Which again is all perfectly legit capitalism.

I think that me and my i14 / 505 / moth / merlin rocket / melges 20 whatever comrades need to start wearing berets and form a cooperative to approach NS for bulk purchase for our OD sails if that will drive the cost down from double panelled to only +25%. Maybe we could integrate our cooperative with our 49er brothers and sister and then everyone wins. How hard could that be Four legs good, two legs bad!

 

[JulianB]

Firstly, 60% of all the sailors at any given 49er worlds are there for the kicks, not for the gold.

Rightly or wrongly, the 49er has become an aspirational boat, in the sense that they aspire to sail it, and some aspire to sail it well with no intention of Gold glory.

We could stochastic-aly verify that (you made me look up that word) but again the feedback from the sailors at the AGM, is more than enough for me.

Re  inconsistency.    These guys get bent out of shape over ¼% (as in 0.0025) and to them it’s very real.   

What I do believe is that 3Di and the claims made by North are about to be subjected to a level of scrutiny not experienced by many ever before.   

Re consistency, if you lay-up over a mold and by computer you should achieve greater consistency.   Even laying up a panel sail over a mould should increase consistency.

The big thing about what the 49er can do, that the 5o5 or I14 can’t do is have a 50-100 mainsail run with no variations allowed or even considered.

Set the machine up once, press the go button and extremely limited human intervention.

ILCA could do it,  and we know ILCA are watching closely.

                           jB

 

[karelchik]

49er/FX D1's go in at the the top of the ram vang, so they are a lot higher up, the angle is far more acute, so they need more tension to have the same result, the flip is that they hold the mast very positively higher up and there for are far more effective.

Hi guys. I am a bit late to this forum, but it has been a great read. Was wondering if Julian could comment a bit more on how to use the lower shrouds?

I have been sailing 49er FX for almost a year now, but still can't wrap my head around the sail trim. On medium wind days the boat just flies, on stronger days we are struggling a bit to depower (after reading this I think that we should try easing the uppers more). But the real struggle is lighter wind (not very light, but light-ish), when we feel that we are lacking power. Pulling the vang on closes the leach, but also flattens the sail a lot, so we don't know where to stop. One theory is that we should increase the tension in the lowers to stop the lower mast from bending and so keeping the lower part of the sail fuller.. is this logic correct?

Also, another part that I would really love to understand deeper is the setup of battens. May the battens be one of the reasons we are lacking power (maybe not enough tension in the upper battens?) or are the batten tensions not as important as bending the mast the right way? Would appreciate it a lot if you commented on that too.

 

[JulianB]

Instead of mucking around with this, let me see if I can get you a set of numbers.   I promissed to do this some time ago, may have to wait until after the games, because people won't want this in the public domain prior to Tokyo.

                       jB

 

[karelchik]

Real numbers would be really great, but to be honest I am more interested in the Why rather than the What.

I have worked trough your fathers (and your) books, and the rigs used in 18footers and 49er seem to be such masterpieces. There is a lot of information, but I feel that I don't get the whole picture yet (or there are some gaps at least), as I'm not able to apply the knowledge in my sailing. That's why I turned to the internet.