How much is too much

I am beginning to play with the backstay adjuster on my E35-III. It has a gauge that reads in thousands of lbs. It is set at 1000 now. How much tension is too much and may damage something?

This is all in preparation for some club racing. I was very sucessful on my '76 Pearson 28 but there is a guy with an E34 with the same rating wanting to see how I do on this boat. Of course, I am just learning the boat and he has had his for 20 years.

I don't have an answer that's specific to your model, but on other boats (similar size range) I've been told that 2500 psi is a good upper limit.

How much?

Our boat came with a Navtec and I replaced it with a Sailtec integral backstay adjuster.
I relax mine at the dock -- couple hundred pounds to keep it snug. Heading out for a sail we bring it to around a thou and for going upwind pump it up to 15 or 1800. Going over 2K will put some bend in our mast, but not much, and I feel like it is overkill. Our main is not cut to take any particular advantage of mast bend, in any case.
I also relax the furling genny halyard at the dock, and sock it up tight when heading out.
My .02 worth,
YMMV,

Loren

Yupyup

Loren nails it again...

Some rules of thumb:

At the dock, keep the genny halyard slightly eased, and keep enough tension on the backstay so the rig does not bounce around in motorboat wakes, etc. This should not require more than about 500 lbs-but whatever it is, you want the rig steady while at rest. Having it flopping around causes wear on all of the components.

When sailing upwind in lighter air, you should have little or no BS (this depends on your HS length). The idea is you want as much sag as you can get without having the HS bouncing around in the waves. A small amount of movement is OK, but if you can see it moving around more than 2-3" while you are sailing, add just enough BS to steady it down. The idea here is that in light airs you want the sag to generate power and provide a "FAT" leading edge-which has a wider groove.

As the breeze builds, you need less power, and the higher boatspeed reduces the need for a high lift at low speed condition (this is the saggy HS condition). The finer leading edge is now preferable in that is has less drag, and power-and while it does take more speed to produce the same lift, you now have that speed, so the idea is to reduce drag. . In addition, the sag will become excessive under the higher loads of more wind, so you will want more and more BS as the breeze comes up. The added benefit, especially in the new 32-34-35-38 series of boats which have somewhat bendy rigs is that the BS tension will also induce some bend, which will flatten the main, and this is needed to minimize being overpowered. So, the BS adjuster helps optimize both the headsail shape and mainsail shape-in both directions; it allows you to have a full main and saggy, full headsail in the conditions where that is fast, and a flatter main, flatter headsail, finer leading edge when that is called for.

While this may sound counter-intuitive, It is a myth that you always point higher with a tighter headstay-you will find MUCH better pointing with a saggy headstay in lighter air, and a wider groove to steer by. Genoas are designed to work with some sag-usually more than 3-4" at all times. In bigger breeze, it will begin to suffer if sag is more than 6-7". The idea is to have CORRECT amount of sag for the conditions.

ROUGHLY 2500 is a good max, PROVIDED the HS is not too long (if it is, this may not be enough to remove excessive sag), and the luff curve on the main is not excessive (meaning it won't be fully flat with this amount of load).

I might go as far as 2700-3000, but that is all. If you are sailing upwind in about 15 True, you should be able to have the mainsail BOARD flat, and the headstay should not have more than about 6" of sag. If you have much more than 6" and/or the main is still full with that loading, you may need to a). shorten the HS, and/or b). have the sailmaker remove some luff curve from the main.

On the older 32-2 and 35-2, I would try and stay under 2500 at all times,with a target max of about 2000-2200 since structurally things are different on those boats.
TReilly-does this help?
Cheers,
S

Thanks Seth and Loren

That is a great explanation. I do understand what the adjuster can do for you and I agree about the fact it is more a question of wind strength rather than upwind vs. downwind. I have a lot of experience with shaping sails to power or depower them from years of windsurfing and Hobie cat sailing. Lots of sailors think the more curve the better but do not understand the friction component of that curve.

I guess I was just looking for the working limits of the adjuster. More info is always better though.

Seth said:

On the older 32-2 and 35-2, I would try and stay under 2500 at all times,with a target max of about 2000-2200 since structurally things are different on those boats.
TReilly-does this help?
Cheers,
S

Click to expand...

Seth,
Does this also apply to an 1982 E-38?
Thanks,
John

nope

The reason it is suggested to limit the loads on the older 32 and 35 is because the masts are deck stepped. The 38 has a keel stepped mast, so instead of compressing the deck, you are putting the loads on the "right" spot. The 38 (and other newer models) have the TAFG (grid structure) to distribute rig and keel loads, making them much more rigid structures than the older boats, and hence able to be loaded to a higher degree.

You can easily exceed 3000 lbs on the 38-Ted and Ben can tell you the numners they have used. I doubt you would need more than about 3500-although I would not hesitate to use that much in the proper conditions (upwind at the high end of the #1 or #2 genoa where you need a tight headstay and a very flat mainsail).

Anything else?
S

Ahh, that makes sense. I've been somewhat concerned about overstressing something by pumping too much on the backstay adjuster. I've only used it a couple of times and at that time wasn't even reading the pressure gauge (was looking at how much I took in by referencing a mark on the adjuster). Yesterday I set it at 500 as we left the dock (seemed to give it good amount of firmness for steadying the mast). Now after reading some of the posts, I've realized that I also need to be careful not to leave it too slack.

It sure is different than my Lightning! There, if we're all hiking hard, traveler is off and we can't keep the boat flat, pull on the backstay adjuster until we can (or pull the backstay as a gust hits). We leave the backstay all the way slack when it is sitting on the trailer (dry sailed).

I also don't have a good feel for halyard and outhaul adjustment for the main, but guess it doesn't matter that much since I'm only day sailing and cruising (although my first mate will tell you that I'm always in "race" mode, especially if another boat is around).

Thanks for your input!
John

No worries

John,

Not as different as you might think-On a fractional rigged boat-like the 30+, or the Beneteau 36.7 I sail, we use the backstay adjuster EXACTLY as you described for the Lightning. Being fractional (like the Lightning), the bs adjuster has more impact on mast bend (and hence mainsail depth/power) than it does on headstay sag-although it DOES have some effect. On fractional rigs with swept spreaders (Beneteau),the upper shrouds also impact the headstay tension to a large degree. On the 30+ with inline spreaders, you would need running backs attached at the hounds to have direct control over hs tension, and since few of those boats are so equipped, these boats depend on the BS adjuster/turnbuckle for HS sag control-although it is not ideal.

On a masthead rig like yours, the bs adjuster controls the HS sag AND mast bend (for mainsail depth/power) simultaneously-although the more rigid the mast section the less bend you can get-meaning the biggest mpact will be on the HS..

The 38 has a fairly bendy rig, so you can have good effect on both, while the older 35-2 will only get about 4" or so of bend (but this will affect mainsail shape)-leaving most of the effect on the HS sag.

The botom line that to get the best performance, you would use the BS adjuster the same way as with the little boat; in a puff, add some BS to flatten the main and reduce excessive sag, and in the lulls you would ease it for the reverse effect..

Same thing, really- a boat is a boat is a boat.
Cheers,
S

John Butler,
I have an '83 E38 and here is how I setup the hydraulic BS adjuster. On the mooring I leave 400-500lbs on it to keep the rig from bouncing around in boat wakes. In light air 800 to 1000lbs seems to do the trick. Around 10kts of wind I pump up to 1400lbs or so. Once the wind reaches 20+kts 2000-2200lbs seems to keep the headstay sag in check and flatten the main nicely. I have not needed more than 2200lbs so far.

Regarding the outhaul. I go for snug in light air and pull with all I have to set it for 20+kts to give you an idea on range of effort. The main halyard I tighten until the luff of the main is razor straight and tight in heavy air. Light air I allow just the slightest slack so it bags just a bit.

The headsail halyard is a different story. I find it takes much more effort to overcome the drag of the sail in the roller-furler groove than I would have imagined. I have to use the winch for the last 1/3rd on mine. I release the halyard tension when on the mooring and tension just enough before going out. I know if I have enough tension or not by looking at the headsail tack. If it looks slightly loose I will winch up a bit more. I try to also consider how much BS tension I will be using. I would seem that cranking on the headsail halyard and then cranking in maximum BS would stretch the headsail even more as the headstay stretches. So playing the correct headsail halyard tension takes a bit of experience, IMHO. I also try to release a bit of tension on both the BS and the headsail halyard before using the roller furler. This was suggested by Nigel Calder in one of his books and seems to make sense.

RT

halyard tension

Rob,

I was a bit confused by your last paragraph...it is natural to need a winch to get enough halyard tension (unless there is under about 2 knots of breeze).
What did you mean by "overcome the drag of the of the sail in the roller-furler groove than I would have imagined"..?

In any case, halyard tension is used basically to locate the maximum chord depth (draft) in a sail in a fore and aft plane. Put simply, more halyard pulls the draft forward, and less lets it move aft under load. This is why as the wind builds, and the draft moves aft of the ideal location, the halyard must be added to bring it back to right area. Generally, in lighter air, you want the deepest part of the chord at about 38-42% back from the luff (percentage of chord length/luff to leech dimension). In heavier air, it should be more like 34-38% of the way back from the luff. If you have a draft stripe, this is easy to see. If not, use one of the horizontal shaping seams as a surrogate draft stripe. This can be considered the "chord". It should ALWAYS be visibly forward of the midpoint from luff to leech.

The problem with using the sag near the tack as an indicator is that by eliminating it in light air, you might pull the draft forward of the optimal location-you do not need much halyard in light air-or you will pull the draft too far forward.

Halyard tension for cosmetic reasons can sometimes be contrary to maximizing performance. If you look at race boats ion light air, you will see lots of wrinkles in the genoa and mainsail luffs..

Let me know if this makes sense, as always

S

Hello Seth,

I was a bit confused by your last paragraph...it is natural to need a winch to get enough halyard tension (unless there is under about 2 knots of breeze).
What did you mean by "overcome the drag of the of the sail in the roller-furler groove than I would have imagined"..?


What I mean is I can raise the main fairly easily by hand, needing the winch only for the last foot or so to put final tension into the mainsail. The headsail is a different story. There is plenty of drag from the roller-furler groove and the headsail boltrope (correct terms?) Enough to require use of the winch to raise the headsail the last 1/3 of the way up. Because of this I have difficulty knowing how much tension to put on the headsail halyard.

I assume that when you speak of draft in a sail that it is possible to control draft in a mainsail AND headsail with halyard tension? One of the problems I face is the 150% genoa leaves me over-powered much of the time. It is difficult to trim this sail in anything over 10kts and get a decent shape. Maybe its blown out, maybe not cut quite right, maybe I don't have it figured out yet.... I do know that its at its upper limit at this point and likely is stretched too far to be correctly shaped anyway. I end up reefing it and the shape goes to pot anyway. New 130% is about to be ordered.

RT

Got it-thanks

I got you now-what may be just as much an issue as friction is the actual weight of the sail itself. A 150 is almost twice as large as the mainsail, and simply the sheer weight of the fabric would require most users to need a winch to get it all the way up. The friction aspect can be dealt with by making sure the grooves are clean and you can even use something like McLube in the groove to lubricate it. Even with that, the sail will be heavy. As an example, a kevlar or carbon sail of the same size will weigh about 50% of the the weight of a dacron RF genoa.

For that matter, you should need a winch to get enough tension on the mainsail also-unles the breeze is extremely light. I can't imagine getting enough halyard tension so that a dacron mainsail of this size is correctly shaped without using a winch for the last 6-8" or so..

Now that the sail is within an inch or so of full hoist, you can begin to think about adequate halyard (yes-this is true for both sails). When you have what you think isabout right, trim the sail in so that it is not luffing at all (completely full), and look for the deepest part of the curve. If it is not clearly forward of the midpoint, you need more tension. If it is very far forward, or you have a couple of inches of very tight cloth along the luff, you need to ease some tension. The sail should come away from the mast or the furler smoothly and form a curve extending towards the leech, with the deepest part of the curve between about 34-35% to maybe 45% of the way back-depending on conditions.

Depending on the age of this sail, it may be blown out, or you may not have had the right combination of halyard tension and genoa car location. Having not enough halyard and the car too far forward will produce the symptoms you described-even if the sail is perfect. If the sail s not too old, a recut may also be in order. Still, that new 130 will be nice to have!

There are some photos posted of 38 mainsails and genoas on other threads-where we discuss draft location-check those out..

Hope this helps!

S

I guess we're getting off track of the original question in this thread on backstay tension (thanks for providing the numbers you use, Rob), moving on to halyard tension. I'm accustomed to controlling draft in main and headsail by use of a cunningham and see where halyard tension can accomplish the same thing. In my lightning, I go by the amount of wrinkle in the luff (usually just pull the wrinkles out on the jib, but often sail with wrinkles in the main since that is how the sail makers designed the sail -- the amount of wrinkles are a guide to halyard tension).

In my E-38 main, I always pull the wrinkles out and if it's a windy day, add more tension to the halyard. I'll try to pay more attention to the draft of the sail (something I don't think I'm very good at assessing). On the lightning, we also put on more main cunningham (i.e., tighten main halyard in the E-38) when we pull on the backstay, but I think this has to do with the mast bend which may not be as significant on the E-38.

Headsail halyard tension on my E-38 is not so easy to adjust. All lines are led aft except for the headsail halyard. However, there are no winches on the mast (lead the halyard aft to a winch temporarily to hoist which requires unthreading one of the other lines). The PO helped me put the headsail (I think it's a 130%) on at the beginning of the season and I haven't touched the headsail halyard since. Is the slackening of the headsail halyard at the dock/mooring done to lesson fatigue on the equipment? The mast must have had winches at some point. Maybe I should install one for the headsail halyard.

For outhaul adjustment, I go by inches off the boom on my lightning (it's not loose footed, but there is a seam that is essentially like a loose foot of the sail). I'm not sure what to go by on the E-38 except the "pull with all I have" that Rob uses for heavy air.

John

Lightnings and 38's

Same thing, really. A 38(or any boat) which is sailed for performance will certainly have a cunningham. Both halyard and cunn are used to control the fore and aft location of the maximum draft. The halyard will impact the top 30-50% of the sail, and the cunningham will impact the lower 30-50%.

Backstay adjusters (or turnbuckles), via the ability to bend or unbend the mast, will have the function of controlling the AMOUNT (as opposed to the location) of draft in the mainsail, and especially for masthead rigged boats, also affect the amount of HS sag.

Bending the mast, on a Lightning or any boat does not really tighten the luff, since it also shortens the distance from the top of the mast to the tack-the 2things offset each other.

Depending on the material used for a given sail, if you use the "wrinkle theory" to guide luff tension, you run the risk of having too much tension (draft too far forward for the conditions). This is not to say that with a soft dacron sail it will lead you astray, but the fact is that for mainsails and headsails, quite often you WILL have some luff wrinkles when the draft is properly located for the conditions-again the age, condition and materials used in the sail will have an effect. But a fresh sail made from any performance oriented material will likely NOT be fast if you eliminate all the wrinkles form either sail in light air. The proper indicator is simply draft location, and not much else (assuming the sail is the correct length and fits the boat, of course). Wrinkles may or may not be present, and are not really the issue.

Same thing with outhaul tension. The amount of tension needed is simply a function of how much power (actual depth as opposed to draft location) you need for the conditions. If it is windy and you are somewhat overpowered (heeling more than about 15 degrees, weather helm, etc.), you must flatten the sail by tensioning the outhaul. If is lighter and especially if it is lumpy, and the boat is underpowered, you should ease the outhaul to increase the depth in the lower portion of the mainsail. Be careful about easing too much when reaching and running (where you can often use the power since you are heeling less on this point of sail), since after a point, you are REDUCING projected sail area and increasing drag at the same time (since you shorten the distance from tack to clew). Having the sail totally "bagged out", as many old schoolers like to do when sailing off the wind, is actually slow. On most sails, my range from board flat to max ease is only about 4-5" at most, often less.

Sailing uphill or close reaching in light air, easing the outhaul WILL increase power (depth), BUT also by making the sail deeper you increase drag-what does this mean? You will accelerate a bit quicker, but top speed will be limited by the drag. In light air racing mode, we ease the othaul a bit during the tacks (since we slow down during the turn), and slowly bring it back to the previous tension once we have accelerated back to speed, so we can get back to top speed again..maybe a bit esoteric-but this is to illustrate what is happening.

You have mostly been doing the right things, and this is meant to help explain why one would do them.

Too bad the PO set the boat up without easy access to a headsail halyard winch-you would be well served to change things around so this is an adjustable function-if, that is, performance is of any importance to you.

Finally, yes, easing the halyards when at rest helps make the sails and halyards last longer-no big harm done if you forget, but it is certainly good practice-especially when you get new sails.