mainsheet tension

How much is too much? I've had two friends, both A Class sailors, tell me I need to sheet my main harder. So, are the two boats similar in this regard? I would say I'm already sheeting hard though certainly not "block to block". It's possible I'm using too much luff tension.

Secondly, Stefan at 75 kb. thinks we could have been double trapped yesterday (I only have the single trap fitted becuase I usually sail uni.) in 12-15knots. Our combined weight is 180 kgs. I'm afraid that if we double trap and "sheet the hell out of it" I'll break something, namely the mast.

I have to say sailing with Stefan is a hoot! The guy has so much energy and is so positive!

Pete, you might break something but it won't be the mast. It will flex and bend but that's what it's supposed to do. Remember though, as you are sheeting extra hard and with 2 on the wire, you are putting a lot of stress on the fore stay, and the jib halyard, so be sure you look those over when you are rigging it up.

You can break your jib halyard if you don't adjust it for correct luff tension with the main sheeted on hard. The easiest way to break it is to tighten it up real tight while the main is real loose, like at the end of the run, or on your way out to the starting line, spin up, mast is being pulled foreward, you tighten up the jib halyard getting ready for the upwind work...but...after you snuff the spin and sheet in the main, and put two on the wire, you will have moved the mast backwards, and you can really be over-done on the jib halyard, so be careful.

Don't ask me how I know.

Pete

As timbo says, be carefull tensioning the Jib halyard.

As for wind speed and 2 trapping, 15 kts you should be de-powering !!!!

Something very wrong here.

How much pre-bend do you have on?

what purchase do you have on your main sheet?

How hard are you sheeting in?

the tension from the mainsheet translates to the forestay. Max mainsheet tension, 2 dudes on the wire at the back of the boat and you hear a crunch. It will be the bows pulling together due to the angle of the forestay bridle. Been there...

you should maximally sheet the mainsheet although it can be over done. I find that lots of mainsheet tension and trav down a tad is faster than trav midline and slightly off on the mainsheet.

For two up sailing, you should have 3mm or better 4mm shrouds and the part of the forestay, which is above the jib luff should be 4mm minimum, the lower part might be 3mm. The shakels 6mm at least. That`s what you find of most double handers. With hulls and mast designed for two, it shouldn´t be a problem.

The main is hard enough, if the leech stands up straight, even with the downhaul on. That`s universal for all sailboats.

Cheers,

Klaus

I can't really discuss 2 up but when 1 up I sheet as hard as I can when I can. This usually means until I physically can't pull any more. The sail is as tight as it can go, if I am then constantly bearing up in the gusts or having to ease the main then I pull some more downhaul on still trying to keep maximum pressure on the mainsheet. This technique is only used in medium wind conditions and I all ways try to remember to ease to the downhaul just prior to rounding the windward mark just to save the sail from over stretching the luff. However, I do forget occasionally ;-(

Prebend is still to factory setting, whatever that is. 6:1 on the main. I think the next outing there will be very little downhaul.

With 180kgs trapped out, I'd think we'd need full power. But what about rotation? 20-30 degrees? Also, it's probably time for a split-tail main sheet.

Personally, I feel that double trapping with 180 kg on the wire in not something the F16's are designed to do. Any well designed F16 should be able to handle any loads that sailing can put it under ; it is just that I don't think that much righting moment balances well with the flexing of the mast.

At some point, high mainsheet tension will only reduce the draft of the sail while also when straighten the leech. These two effects oppose one another in the feel of power. I believe you feel just as powered up but the craft is overall slower just the same.

I feel sailing that F16's (and yes I'm not a world champ) is more about getting the draft profile and twist profile right then about keeping 2 men on the wire. You trim the sail for maximal drive / speed and you go in or out of the trapeze to maintain that sail trim.

Now I don't feel that unless you sail is cut for 180 kg that you can keep 180 kg on the wire and still have the optimal sail trim for performance.

Basically at 180 kg you have 120% the righting moment then a 145 kg crew trapping. If your sail is cut of say 145 kg then going single trap with reduce the overall righting moment to 105% of the 145 kg crew. It is my believe that this matches the shape cut into the sail much better and you'll probably be sailing with a little more draft and a better twist profile.

This has also been my experience on my own boat. Agreed my mainsail has an error up top, but it just performed better with me hiking and my 70 kg crew trapping then when we both went to the trapeze. Back in the time of these experience I was about 90 kg.

Wouter

Pete,

You need to find a tune-sheet for your mast. with a 6:1 I'd suggest you need to pull real hard. but not over sheet. Time to scatter some tell-tails over your sail. I'd start witha like of about 4 about middle of the sail for the top coupe of panels and then about 60-90cm from the luff and also a settof leach teltails. I would also stick some teltails on your mast!

I would also think you do not need much pre-bend, but still plenty of tension in the diamonds to get some power in the rig!

Pete,

if you lack upwind speed/VMG, listen to your friends. If not..
They are in a better position to study your leech than you are. If you dont sheet hard enough, you dont have the pedal floored, and if you are racing, you want .
If you are in doubt wether you have enough sheet on, look at the telltales. Are they streaming? What happens if you sheet the main a bit harder, still streaming? Sheet in until they stall, then let out until they stream again. Have your crew on the main and let him work the sheet to the above rule all the time while you focus on the water and helming the boat fast. You probably need more sheet tension than you think, but your telltales will help you, if you look at them that is. I dont like to have too many telltales on the sail/rig. That is just confusing in my experience, and you end up using just a couple of them anyway. Your main probably came with all the telltales you need.

If you have too much or not enough donwhaul on, the boat will be slower than it could be. The only way to tell is to look at the boats around you and spend time in the boat so you get the feel for it. If there are other boats with similar sails/masts and crew weights around, ask about their settings after the race. In 15 knots you probably want the downhaul on quite firmly for best speed.


I would listen to mye friends when telling me that I was not sheeting hard enough for the conditions.

I have whip marks across the tops of my thighs! That's from Stefan popping me while sheeting in and out! Part of the confusion is that I'm driving the boat hard and not doing much else. That's Stefan's job!

It's all good! We'll give it another go this weekend in Daytona. If we can get through the surf!

Pete,

DO NOT buy a new sail, for one thing, baggy/full sails do NOT work!! They are dog slow. Just ask people who have done sail development programmes!

You will suffer in the ligher wind speeds, but I would still expect you to be fully/over powered in 15kts (top F4).

As Rolf says, get people to sail behind you and look at the leach profile and how the sails are setting. you should be well powered up in 15 kts!!!

Next time youy are at the boat, take some pictures with the sail up to show us...

Two other items I would like to comment on:

1: Twist.. In chop twist is faster in my experience. In weak winds, twist might be faster, in strong winds, you will not be able to sheet hard enough to remove the twist anyway (mast bends, sailcloth is flexible etc.)

2: Sail design and custom sails for crew weight, dominant conditions, skill level etc.. Dont bother, go with what you have or the class "standard". The margins are so small and the risk of actually buying a slower sail than the class standard is pretty large.

Keep it simple. Simple is fast


Good luck in Daytona. Hope you and Stefan get a few hours on the water to practice your boathandling and teamwork before the regatta.

(PS: During strong wind regattas my crew, Frode, sometimes bent his legs and sheeted in by straightening the legs with a stiff body and a super-firm grip. That was with a 1:9 purchase on a Tornado rig. Then he began using his arms and back for small adjustments. Just to give you an indication on how much sheet tension we used at times. Not saying that you want to do this even if we did. We are/was not world class sailors)

We had a blast at Daytona!

BTW, the advice is unanimous; from A Class to N20, everyone sheets much harder than I. Of course, I'm not Stefan! He sheets the hell out of the boat! (and it works!)

So what are the tecnical requirements, especially sailing Uni? Who uses 8:1 blocks? 10:1? Is a tapered main essential? I'm certain a split tail is necessary, as is, the whole traveler car jumps around making sheeting that much more difficult.

I recently converted from 6:1 to 7:1. It was really easy to do, I just added a spring supported block where the sheet used to finish on the bottom block, and attached the sheet to the unused bracket on the top block. I had to get a longer sheet however, but I reused an old spi sheet I had.

7:1 is better than 6:1, I can get it tighter with one hand that I use to be, and that's an improvement upwind. I think 8:1 would be too much rope to pull. I'm now going to reduce the amount of sheet needed by making a tail to lower the top block and then probably make a taper.

I made myself a poor man split tail (a dyneema loop on one side, the traveler line goes through the loop and attach to the other side). To have the car not move at all when you sheet in was a good improvement.

Cool! Sounds like you have had a revelation
What kind of windstrength did you have at Daytona?

About split tails. They are useful for centering the car, but the car will still move a little bit even with a split tail.

Any friction removed gives you exactly that much more power to sheet in the main with. Tapered sheets reduces friction. Cascade in-boom sheeting might remove even more friction.
If you are not strong enough to sheet hard, more purchase and some strength training is your friend. Adding ridicilous amounts of purchase have its drawbacks!

If you are serious about wanting to sheet harder and your present setuo dont work for you:
1: I would look at the sheeting technique and setups used in the A-class since you have them close to you. Ask the guys how they do it and learn their technique before changing your boat.
2: Begin working out to gain strength (working out is free, so the price is right).

Did I piss you off now?

No you didn't piss me off! The wind at Daytona was mostly 8-10, sometimes a little lighter. We were getting some crazy puffs that were not so much stronger, but Changed direction severely. Trying to keep speed and come up with the lift, I almost went over once.

Pepin: I'll try your poor man's split tail as my splicing skills are non existant! And now that you mention it, I think I already have the 7:1. It was standard on the boat and I changed it out for light air work and never went back to it!

Pete,

there are many ways of making a split tail without splicing. Be creative and get a large needle+sailmakers glove. If nothing else, stitching the tail to the traveller line will do the trick, even if it is a but crude. Pulling the cover of the control line back, then stitching the tail on in different ways is also feasible. Think a bit ahead then Get To It


Did you see the gusts coming? Instead of coming up in short blasts, how about sheeting a bit out and sailing through them with greater speed? Depends on conditions of course.

Yes, we could see the gusts coming. I have a clear memory of, not sheeting out, but falling off a bit and going through with greater speed; and watching Matt/Gina as well as both Tigers climb W-A-A-A-Y above us! In this case the gust was usually a huge lift.

Wait! That can't be right!?? (so much for clear memory)!

Maybe Matt will give us his version. He and G. seemed to really take advantage of them.

Hi Pete,

the best way for me to know how hard to sheet, is the usage of tell-tales on the leech of the sail. If only the top one are absorbt, you sheet to hard. If the low one are absorbt you don't sheet enough. I had to learn that I have to use the proper rotation for a wing mast as well. A wing mast needs to point much more in the direction of the boom than a conventional mast and this will close the top of sail as well. I use the "poor man's split tail" as well and it is absolutly sufficient, but not as nice looking as a true splice.

Cheers,

Klaus

Absorpt? Do you mean stalling?

Yes. If the sail is stalled, the air flows from the leech to the middle of the sail, hence sucks or absorbs the telltale to the leeward side of the sail. Normally the sail stalls from the leech to the mast, so the leech telltale is the most sensitive for avoiding a stalled sail.

Cheers,

Klaus

I was confused by your choice of words. "Der leech telltale sindt absorpt" will go into our sailing dictionary now (my excuses for "radbrechen" your language)
I am glad an aerodynamist have the same view on leech telltales. We had a hard discussion with Rick White amongst others some time ago who advocated dropping leech telltales and going by the telltales at max draft or thereabout. Simple is fast, but that was a bit too simple I think.
Would you care to guesstimate how large the difference could be between sailing with a streaming telltale at max draft and the section aft of that stalling, vs. sailing with telltales at max draft(or in front of max draft) and the leech streaming?

Not too bad. In strict German it would be "Die Achterlieksverklicker sind absorbiert." I am sure that normal german people wouldn't understand it.

It depends a bit on the boat and point of sail.
First some numbers:
alpha, cL, L/D, % sep
10, 1.23, 65, 100
12, 1.33, 50, 90
15, 1.38, 28, 60
18, 1.33, 14, 40
The first number is the angle between wind and sail (angle of attack). The second number is the lift (cL) of the sail, the third number the lift to drag ratio and the last one is about the point where the flow stalls (0% is the mast, 100% the leech).
While beating with fast boats cL and L/D are important, but with stronger wind cL is less important. The higher L/D the better the vmg. For only a bit more cL you pay with a lot of drag and you will be slow. On all other courses, cL is relevant and you can forget about L/D.
Going upwind, leech tell tales are very useful. Going downwind without spi, tell tales at 60% at the leeward side of the sail are useful. With spi, the main is tight anyway and you control the heel with the traveller (or main).
Tell tales at 30% on the windward side are useful to find the right angle of attack.
The numbers above are from a aircraft airfoil, they will be different to a sail, mainly in terms of drag, and they include only what we call profile drag. But overall effect will be the same.

Cheers,

Klaus

"Achterlieksverklicker".. So what do you call a telltale on the jib? "Vorsegelverklicker"?

Thanks for the numbers. Stalling the flow over any foil (like a sail) is pretty bad! So there you have the numbers Pete. Undersheet and you loose a bit, oversheet (stall the flow over the sail, or or not helming straight) and you are parked compared to those trimming it right.

Of course, undersheeting a lot is not fast either..

Danke.

Gina, I've seen your hands after you've crewed for Matt. I can assure everyone here she is NOT just "along for the ride"!

And she's got guns guys, and not afraid to use them!

Okay, what do you did you do when the big headers or lifts came along?

I think I just yelled stuff like: "Go faster!" and "Do you see the mark?" Just stuff like that. I'll find out what Matt does and get to you. And Tim, you are so very good for my ego. Thank you.

"Go faster!"- universal crewspeak!

I spend a lot of time yelling at my skipper too; "Go Faster" or "What the Fark are you DOING??!!" or "Tack NOW you Jackass!"

But that's only when I'm sailing Uni. ;^) Seriously, I talk to my self alot out there. Keeps me focused.

Pete, according to Matt, sometimes you can see the lifts and headers and anticipate. But usually, there is a trend. Gusts in one part of the course and almost always a lift or almost always a header. You just have to get into it and see what happens. Ex. There is a big lift just before "A" mark or whatever the case might be. Oh, and he always asks his crew what is going on on the course and she always replies with "everyone else is going faster and higher". It always seems to work for me. He plays great "catch up".

Klaus,

Thanks for the information. On the downwind I also trim the main that the leech tell tales are flowing and I have the feeling it adds a lot of lift (so alows me to sail deeper).
To adjust the main I always leave the traveller centered and ease the main. Anyone that does the opposite and is this better/worse for drag?

I dont know what it is worth on the F16, but in the T we always eased the traveller about 10-15 cm before trimming the main. Then, if you were daring with the alu mast, you trimmed the mainsheet in gusts/lulls. Playing the traveller was the safe method if you could not afford a new mast.


Digression: When the carbon masts was put on the T, the traveller was eased less but the mainsheet could safely be eased more than with the alu stick.

Not quite I believe Drag is still relevant in my experience, which is purely practical and founded on just my own meager experience. The classic example was back in 2002 when the Gran Segel spis from Sweden made their debut at the worlds in Marthas vineyard. These sails had less draft than the current best spis from other sailmakers (but were also made with more panels=more stable design). The boats with the spis from Sweden were much faster than the others. I think this was becouse of less drag (and the ability to build more virtual wind). Together with Marcus we did a Tornado spi with more draft back in 2006 (right Marcus?). The spi had loads of power, but it was very slow. Drag was too high I think as it did not accelerate much in gusts (but was outright scary to sail with).
I also read about the L/D dont matter theory in one of Marchajs books, and now you say the same. Klaus, could you explain just why this is for us simpletons?

Hi Gilo,

I does the opposite, because I don't know, what my mast can support. But for boats where the gennaker doesn't end at the top of the mast, I guess that trimming the main with a fixed traveller is more logic (the top of the sail needs to be more open, hence more twist, because it isn't in the 'downwash' of the gennaker. 'Downwash' is the flow affected and behind of the lifting surface. On aircraft it goes down, hence the origin of the name. On a sail it is a sidewash).
It is certainly better for drag, but we want maximise speed and not minimise drag... and keep my boat alive.

Cheers,

Klaus

Hi Rolf,

I am not less 'simpleton' than others. I sail since 2000 on week-ends in the summertime.

On my Dart 18, the gennaker was too full as well. To understand we have to have a consebe clear about lift, cL and draft (or camber) of the sail. More draft doesn't automatically means more cL or lift.
Lift is a force, cL is a lift coefficient and the relation between the two is lift ~ cL x v², where v is the apparent wind speed.
The luff of a sail without battens collapses in case of small entry angles. A full sail needs greater entry angle than a flat sail. Hence the smallest possible angle of apparent wind depends on the draft of the gennaker. It is rather geometry than L/D.
You can create lift with cL or speed, and due the power of the square, speed has the longer lever.
Take a flat sail and point higher so the apparent wind is stronger, and you have more lift with less cL than the full sail.
Now the lift accelerates the boat. The lift increases even more, but instaed of sheeting out, you bear away and keep the apparent wind speed more or less constant, but sail more deep and fast than the full sail.
So it is the entry angle and not drag, which requires to have a flat gennaker.

Cheers,

Klaus

and right now 1:0 for Germany:England (U21 championship, soccer)

Ok, you are saying that the advantage of the spis with less draft was the sharper entry angle and thus being able to build more virtual wind. Not much to do with L/D at all but "simple" geometry. Mmmm, I'll have to re-evaluate Marchaj Thanks!

Enjoy the game!

On the H16 we used only the leach tells to set the sheet tension. With the big head sails, we started putting on tells there as well, but quickly found they told us nothing. The top ones especially as the way the sail is designed to operate, they always flowed due to the natural twist induced with downhaul and rotation. It may be different without the wing mast, but I just use the stock tells now just off the luff as that shows me in much better detail if I have the correct rotation and sheet tension.

Off the wind with crew I can fine tune the sheet tension with changing wind pressure, but to keep heeling in control or to reach we play the traveler.

We have found we like the flatter spins as the point of sail is safer to keep the apparent wind forward. I do not think (wthin a reasonable range of cuts) they are faster around the course though. You have to sail to the cut you have. What is slow is they guy trying to run deep (or high) to match his buddy who has a differnt cut or different condition sail.

Sorry for resurrecting an oldish thread.



So are you qualified for the next worlds yet? Norway is probably not going to qualify for this event


To the point, here is a nice article about Ben Halls wing: http://www.sailingscuttlebutt.com/news/09/0810/

What I found relevant to our discussion was this:


So flatter was faster even with a solid wing. I am so fond of the "less drag" thinking based on my experiences that I want to say that this is why they increased the speed with the new setting, but of course geometry is still geometry.

Be interesting if this was simply spedd thru the water, or VMG was better too as sailing further; but faster; or even sailing faster so apparent built so could bear off more anbd thus better VMG....

You will have to step me through that one Simon.. Are you saying that it is logical that flatter gives better VMG?

The next time I forget to let off the downhaul DURING the downwind leg I'm sure I'm going to remember that less draft/camber = more speed.
I've only just got into the habit of letting off the downhaul prior to the windward mark so as not to overstretch the luff whilst easing the main and traveller.
Oh well I might as well use one of John Pierce's famous quotes;
"The mainsail doesn't know you're going downwind!"

First off with the downhaul, _THEN_ grab the spi halyard

On the Tornado in the days before we got the spi we used to pull on some downhaul when conditions were extreme but we still wanted max speed downwind. It calmed down the boat a lot in my opinion.

I noticed Glenn Ashby saying that the downhaul should be let off before rounding the top mark on the A-cat some time ago. He should know even though I do think it is the luff rope and tape that carry the load from the downhaul, not the panels. I am not going to say against Glenn on the topic.

Hiya Mark, I was talking about the Solid sail. With Solid sails, you can create massive camber if you want to, but it is high drag.

I'm GUESSING Gashby sailed it more like an A class rig (so still fairly tight mainsheet, with about 12-18 inches of traveller eased) and then fly a hull downwind.

We have sails that we can only take from small amounts of camber to flat. A 3 part wing you can tune to give it much more camber and I assume this is what Gashy was doing different. Geep airflow over the sail going faster.

Mark, I totally agree, we have to let our downhaul off to sail down wind as we do not have very tunable sails compared with a Solid sail!

Hi all,

well all depends how full your sail can be. If the sail is to full, it will not create more lift, but less, because it is partly stalling. And less lift on a downwind leg is slower, as I said, you can forget about drag on downwind legs. So yes keep your sail flat, but not as flat as on a upwind leg. As mentioned before, tell tales on the leach will help to find the right point.

Finally I would not compare the settings of a solid wing with a soft sail. For most airfoil sections without slots more than 5%..7% camber will not improve lift capability, on a soft sail this might be the up-wind setting (including the mast in the camber calculation).

A bit off-topic: The performance of a wing sail against a modern squarehead sail has still to be proven. Last true competition was the rig selection for Stars and Stripes as far as I know, and soft sails has improved a lot since then.

Cheers,

Klaus

This is also a good idea because, in the event you pitch-pole going downwind, your fragile carbon A-cat mast won't be in full compression when it hits the water - reducing the chance of a failure.