Hydraulic Backstay

Finally finshed. Works great. Time to go sailing and see how it performs. I will follow up with bend shots.

These are with just under 1000lbs and then right at 2000 lbs. The shots arent so great but the bend appears to be pretty even. I may back off the aft lowers just a touch more.

Very nice! It is interesting that your later model boat needed to have the rear rail modified to make it fit. My Navtec unit puts the backstay on the outside and it clears the rail by 2 inches or so. Of course, now my Navtec unit is leaking and needs rebuilding..... Watch for that. RT

Nice

Ted- looks fine. At the lower tension, I can see where you might want to back off the aft lowers a tad, but not much, since the 2000 pound shot looks close to perfect-if you do back off, limit it to a single turn on the aft lowers.
With this (nice) bend, I expect your main is very flat at or slighly above 2K-which is what you need once you have 10+ TWS upwind.

For light air sailing-remember you want LOTS of sag to optimize pointing (jn light air), so this could mean none- to maybe 500 pounds. Reaching you will want slightly less sag, BUT you still want the main full, so you might sail with a few hundred pounds on a light-ish jib reach.

The goal in lighter air is to have a good amount of sag, but not have the HS bouncing around so much that the airflow is disrupted on the headsail-season to taste.

Good job!!

S

Ted
Nice curves!!! :clap:
Have fun & sail fast
Bud E34 "Escapade"

First real test of the adjuster, rigid vang, shortened headstay, 6:1 traveler, 7:1 mainsheet, 8:1 outhaul... basically all of the rigging mods I have been working on for the past 6 months. Breeze was 14-16 kts from the north and a full moon. How did the boat perform: in a word WOW. The changes have made this a new boat. We were able to carry the full 150 and main upwind with about 1800lbs on the bs. and about 3-4" of headstay sag. The helm was at 1:30-2:00 and everything was perfect. The main looked great, my 1998 dacron 150 was flatter than I have ever seen it. Prior to these changes the boat would have been on its ear with that sail combo in 15 true. Helm used to be 3:00 -4:00 with the rail practically in the water. My knot meter was fouled but GPS was showing 5.8-6.1 at 30* apparent. If I dropped it down to 32-35 apparent speed jumped to 6.6-6.8. All the new controls make it like sailing a 38 foot dinghy. I can get shape when I want it, most of the times with one hand, and most importantly I can depower the boat without sail changes. I am pulling the trigger on the new 150 from Quantum today and plan to race the fall Leukemia Cup to Baltimore race. We stayed out till 1am last night because the tide was so low I needed to kedge my way back in over the lump at the entrance to my harbor. Still need some work with the downwind setup but thats for another thread.

I also have a bs adjuster on my E34 but I can never get a bend as seen in those photos. I think the mast was replaced by the former owner, a supposedly a Sparcraft “Blue Label” racing/cruising double spreader. It is not oval but is more rectangular. It is tapered a little up high. So what am I doing wrong?

I should add that I have no problem reducing headstay sag in strong winds. My aft lowers have probably around 600 lbs pressure.

I'm sure others will chime in here, but I would suspect one of 2 things could be preventing you from getting bend.

1. New mast may be too stiff to bend. This is very unlikely unless your boat is older say 1970's vintage.

2. Standing rigging tune is preventing bend. This is most likely the cause. I would check your aft lowers for being too tight. I would also try easing your forstay a little. Too much easing on the forstay could give you too much rake, but if you really dont get any bend than maybe you dont have enough rake to begin with? You should be able to put 4-6 inches or more of bend in to this rig. How much tension are you putting on with your adjuster?

The boat is a 1987 E34. Supposedly the mast is a racing type according to my local sailmaker. It is tapered at the top and looks very much like the photo in this thread.

I now have 600 lbs on the aft lowers. With the BS with no tension, the forestay, with furled headsail on, will wobble considerably from side to side, so it seems to me is not too tight. With this and 2000 lbs BS tension, I get about 2-2.5 inches bend and it is very gradual all the way up the mast. With 2500 lbs I get maybe 3-4 inches. If I apply 1500 lbs there is very little bend.

By the way, to get that tension requires something like 3-5 inches taken up on the BS adjuster... but that is from my memory.

The boat is a 1987 E34. Supposedly the mast is a racing type according to my local sailmaker. It is tapered at the top and looks very much like the photo in this thread.

I now have 600 lbs on the aft lowers. With the BS with no tension, the forestay, with furled headsail on, will wobble considerably from side to side, so it seems to me is not too tight. With this and 2000 lbs BS tension, I get about 2-2.5 inches bend and it is very gradual all the way up the mast. With 2500 lbs I get maybe 3-4 inches. If I apply 1500 lbs there is very little bend.

Ahhhhhh, so!

I did not realize we were talking about THIS vintage 34-I thought you have one of the late 80's or newer-which is a similar boat in terms of engineering and construction to the 35, 38 series, etc. It has the TAFG, and was a cruiser racer more than anything else. It was NOT strictly designed to an rule (especially IOR), although it has some IOR lineage.

Your boat the 34-3/4 tonner etc. came in a flush deck version and also a cabin top version. The Tall Rig variants were awesome boats upwind in all conditions, and pretty good around the buoys in light air no matter what the angle. The were weaker reaching and running when the air was up-not much waterline length for the sail area, or ballast, and a hull shape (largely determined by the handicap rule it was built for) that was a better uowind/light air shape than anythihng else. All in all cool.

My friend Steve, who owns Rogue (and is a denizen of this website) will likely chime in now that he sees what boat you have. His boat was originally a 34 Flush Deck with the std. (short) rig. This boat liked a lot more breeze than the TR's but was and is a great upwind boat. Steve was kind enough to get me involved with a Turbo/re-hab of this boat-with a much taller rig, longer boom, full size A-sails for downwind work, and more. It is PHRF killer!!!

In any case, this particular mast was actually very stiff in fore and aft column, and as you have observed, somewhat bend resistant. The rig did not usually come with fore and aft lowers-just a set lowers on the same line as the uppers and intermediates, so they were of no help in inducing bend. If you actually DO have aft lowers (this was mostly on the trunk cabin version of the 34T), leave them somewhat looser than the uppers/intermediates.

The boat DID come with a babystay, which is a very adjustable inner forestay, and was used "back in the day" to induce bend down low and also to help steady the rig in big seas. It usally was attached to a deck padeye with a beefy purchase system, or to a car on a fore and aft track, which was adjustable also via a purchase system or often hydraulics. Some of the more noodle-ish rigs of the day really needed the baby stay to keep the rig in the boat-but not yours. Most have done away with it since in clutters the deck and makes tacking harder as the genny has to clear it each time.

The result of getting rid of it is the loss of some ability to bend the mast-BUT....who says you need more than 3-4 inches"

The reason we bend the mast is to flatten the sail-BUT when a sailmaker designs a sail, he first finds out how much bend can the mast obtain under typical sailing conditions. If the number is 4", he will usually use 80% of that, or 3.2" for the amount of luff curve he will add to the sail. The 2 ways of adding depth to a sail are seam shaping and luff curve. The idea is that by the time you have put in most of the available bend, the luff cuve has been pulled out of the sail (matching the mast as it bends), and hence obtaining a very flat shape. If the rig bends 12", then a designer (for a race sail) will usually use something like 9.6" of curve-again 80% of the available bend. This way, the owner can go from completely full to board flat by using about 80% of the available adjustment on the backstay. Having a lot of available bend is only good if it matches the luff curve in the mainsail. A desinger for your boat will use very little luff curve, and prefer to add most of the depth of the sail in the shaping seams (which will also beome flatter as BS tension is added-but not at quite a high a rate). Mainsail sfor boats that are more cruisy in nature will typically use much less overall luff curve-the reason being that many owners do not use BS adjusters, and having a sail that is too full is no fun except for the lightest of air-way better off erring on the flat side..

When you have a mast that is not very bendy, then the load will go more directly to the headstay-giving you faster, more precise HS sag control than a boat with a very bendy mast might have-you will both get where you are going, but at different rates-both are equally good and desireable.

The idea is for a sailmaker to match the bend characteristics of a given rig so the owner gets maximum adjustability-and the section/tube in your boat was a race section for the say-very different from todays E-rigs, and unless you go to a long throw cylinder and replace or use the babystay agressively, you will live (quite happlity BTW) with 3-4" of bend!!

Hope this helps!!

S

The bends

Doug
I have the hydralic backstay on Escapade (1988 E34 #265) and I get the same results as Ted shows in his photo's. My headstay is "loose" when full off and I add the approiprate amount of tension as needed. Have the rig tuned for slight weaher helm @ 10-12 kn true wind w/155 & full main. I really pay little attention to preasure gauges but watch the amount of cylinder travel to determine where to preset the backstay. I have little trust in the accuracy of these gauges other than to give you an idea of if you are duplicating a previous setting. I other words the preasure value on your gauge to achive a certain amount of bend might be totally different than my indicated preasure for the same amount of bend. I use an old batten taped to the side of the cylinder and mark the relative settings on this "gauge". Much more useful than trying to read a tiny gauge face while rounding a mark in traffic!
I believe your's is the same hull as Escapade (late model 34) rather than the one Seth is refering to. Mast is tapered @ the top, double spreaders, etc. I do leave my aft lowers quite loose to make sure the mast doesn't invert (bend the WRONG way, a very bad thing, BTW) with good results.
I might get up to the boat this afternoon and if so will try to remember to take a couple photos if you would like.
Have fun & sail fast
Bud "Escapade" E34 #265

D'ooohhhh!!

Obviously in my early fog I did not see the "87" in the earlier post-so, yes-Bud is correct. :nerd:

I guess it was the description of the mast-it does fit the description of older 34 rig, and I am confused about this section you describe. If in fact it is some off brand replacement-I still think it should be similar in bend characteristics.

Back to the point (oh, and all of Bud's comments are perfectly correct), it is still true that there is no need for more mast bend than you have luff curve in the mainsail-this is what counts most. Most of these newer boats a have more than enough bend available when tuned for it.

For you, I would start with the cylinder-how much throw do you have from buried to extended? Should be close to 12". Also, your headstay may be a bit too long. It could be the first half of the cylinder throw is just taking up slack in the HS-I would bet that without BS on, you have a lot of sag in any decent breeze.

Finally, if the mast step is all the way fwd. and it is middle or aft in the deck partners, this will impede bend-ability. Then, we get back to fwd/aft lowers thing.

If your main is quite full and does not get flat enough with the cylinder buried, and/or you can't get rid of enough sag, I would 1). Shorten the HS-hopefully you have enough adjustment in the turnbuckle furler/drum. 2). With the rig loose, set the step in the aft postion downstairs, and block it fwd against the front end of the partners. 3). Set up the fwd lowers quite a bit tighter than the aft lowers, and get the rig set up so that when close hauled in about 10-12 true, the lee shrouds (all of them) are still snug. If they are loose and moving freely in 15 knots TWS and above that is OK-but they should have some tension (on the lee side) in 10 and under.

All of this should double what you are seeing now for bend, but again, if you are not having trouble getting the main flat enough, and the HS does not sag too much in over about 12TWS, then the PO likely set it up properly for the sail.

Thanks for the wake up, Bud!!!

Seth, a superb answer as usual but as you agreed, alas the wrong boat!

And by the way, I race the boat rather successfully but often have to simply let the main luff lightly in heavy upwind conditions. Yet the boat points well as compared the Sabres and C&Cs adjacent.


Probably the most frustrating point here will be the mast itself. To make a very long story short, the former owner did replace the original mast, and it looks very much like the one in the photo here. I am emailing the USA distributor in Charlotte to ask bout the "Blue Label" name for the mast to see how bendy it is supposed to be. This is probably a starting point.

Also fyi, in my dock tests, the boom was sheeted hard down and the topping lift tight.

Also... the unit unfortunately takes a varying uptake in the throw for a give lbs due to the a difference in whether all the throw was released previously or only partially. Probably due to aging. So I can use the measurment idea with reservations..

I did think I could actually move the mast step. And the mast has almost no room for movement forward or aft at the deck partners.

Your suggestion to shorten the HS is puzzling me right now. I had thought the only thing left to do was to lenghten it. (?) Actually I am able to get a very tight headstay(in 15-20 apparent) at about 2000 lbs (the meter seems reasonably consistent). In sailing conditions of those winds and more, the sail in flattened but never board flat. I also use a flatting reef since the sail has a foot shelf. also have battens.

At 2000 lbst as measured at the dock, the bend is no more than 2-3 inches and some of that may be only observed due to the mast leaning aft. Clearly it does not bend as shown in the photo. At 2500 I get more. An experiment at the dock: I took it up through 3000 with a little more tension and then for the H of it I took it to 4000 and the BS tripped at the preset upper limit of 4000 - I did not observe the bend at that point. THe BS is a Navico, one of those square bodies, with something like 9" throw or so (cant quite recall here). When released the BS unit flops around. When even at 3000 I have probably 2" plus remaining in the throw.

From all this it would sound like a stiff mast. I may not be able to get back on this until late next week.

Spar section changed in June 1989

I have been in contact with Sparcraft who supplied those masts. I will have more to report but I need to confirm by photo with Sparcraft to make certain which mast I have. It appears I have the mast section which became standard on the Ericson 34 (at least) in June 1989 (rectangular as opposed to oval) and the bendability is "20% less" (and described as "relatively stiff") but the weight aloft is less. The pre-6/89 mast was 3.64 lbs/ft and the later mast was 3.49 lbs per foot but maintained the strength desired.

I will have to get back late this week or early next week to confirm what I have, but the info should be informative to all.

Interesting stuff

Until we get more scoop on the section, I will make a short comment on your post:

You are generally doing the right things at the right times-and seem to be getting good results..

As you may have surmised, using indicated pounds of pressure is not very accurate, and even less repeatable. As handy as it should be, it is not. As has been suggested by Ted and Loren and the gang, the best thing is to use a batten with lines at roughly .5" intervals, and a piece of tape or marker on the BS itself-and line the tape on the BS with the batten marks. This is quick, accurate and repeatable. The pressure indicator is not worth much.

I am curious about the main sheeted hard/topping lift tight method to check bend or tune..can you share this rationale with the class?

I generally lower the boom to the deck when dock tuning/checking BS settings so there is zero impact on fore and aft or side to side loads from the boom.

The comment about shortening the headstay was so that the BS tension would be restricted by the length of the HS (after some stretch of course) and it would then begin to bend (compress) the mast sooner. A longer HS will take longer to get tight and hence one would need to use the first 1/2 (or whatever) of available throw taking up HS slack-this is why I suggested it..but if you are getting a tight headstay already-this may not be the problem.
Once we have sorted all of this out (and you are satisfied there is enough throw-9" seems shorter than average) and still feel something is not right, you can still improve things with the step, partners, and fore/aft lower adjustment...

Seeya

Oh-and....

Don't forget the most important thing I feel I have said on this topic:

Who cares if you don't have more than 3-4" of bend? If you have good control over the sails and HS sag-you don't need anymore!!

Let's not get hung up on bend for bend's sake, OK?

Cheers,
S

ditto

Yea, what Seth said. I guess I really don't pay as much attention to the numbers as I do watching sail shape and the "feel" of the helm when determining the amount of backstay tension. This also goes for setting the lead car positions, mainsheet & traveler, vang, etc. Every time out is a little different and every boat, even though they came from the same mold is slightly different due to the cut of the sails, placement of weight, and so on. All these "rope thingeys" that we have are nothing more than tools to maximize what you have available on your boat. To buy a performance sail from a sailmaker who doesn't come to your boat to see & measure EVERYTHING is a setup for disappointment. Doug, if your mast is stiffer than mine or Ted's is not as important as haveing your sail cut to match it as Seth said. Everything needs to be "in tune". A good sailmaker will be happy to come out & sail with you and see if everything is working together or if you will need to have something adjusted to suit your gear. They want to see you happy with their product as this is their best advertising.
Have fun & sail fast
Bud "Escapade" E34 #265

Hey Bud

Thanks Bud for amplifying my thoughts on the way to use/interpret backstay settings!!

The batten indicator is really best used to duplicate what you may have had on the last beat, or to get you in the approximate settings for the condtions.

For example-you sail the first beat in 15 kts TWS, and after trying a few settings to get the best combo of mainsail depth and headstay sag, you see the BS lines up with mark # 6(as an example). When you round the top mark and head downhill, you will ease the backstay all the way off to get the masthead (and CE) forward to improve depth (as oppsed to pointing ability) and raise the leech of the main just a bit more. As you approach the leeward mark, you have to put the backstay back on, and you can go right back to the #6 setting so you are the ballpark as you start the beat. If you noticed it has gotten lighter, expect to ease the BS off slightly after rounding (or if the change is dramatic, just set it up a notch or 2 less). If the breeze has built, start where you left off (#6) and expect to add more as you get the boat to speed and upwind trim.

And, as Bud says, each day is slightly different in terms of waves, wind, air temperature (the colder it is, the denser the air, so that 10 knots TWS in 40 degrees F is a lot more wind than 10 knots in 80 degrees F-and you would need the sails flatter for this amount of wind on a cold day as opposed to warm day)-the point being is that you should "season to taste" for the conditions. Still by making some notes on the settings of rig tension, backstay tension, genoa car placement, outhaul, cunningham, etc. for different conditions you can get the boat tune in the ballpark right away, and then you can fine tune as needed by conditions.
Bud also mentioned sail shape and feel being more important that the cylinder indicators, and this is what we saying.. but what does that mean?

It means that you should be experimenting with some of these tuning variables after setting the coarse tune values from your notes, and see how the boat "feels"-meaning is the helm pressure, heel angle, and overall balance for the conditions acceptable...sail shape is obviously part of this, BUT USE the speedometer, NOT just sail shape. Often a sail may appear to look good, but may not be producing enough power (or too much), so until you have developed a very good feel for this (and even after), use the speed more than how the sail looks. We have all heard about "speed wrinkles", right? Sail looks ugly/boat goes fast. Go with the trim setting that nets the best speed.

It is best NOT to use GPS for speed tuning, as there is a delay in the rate of update on a GPS, and of course the GPS only gives you groundspeed. A knotmeter will tel you quickly if the changes are good or bad.

The stuff about the sailmaker's responsibility is 100% right. Good post, Bud!!


s

Bs Lines

For those of us who can't tell the bs from the bs lines what are they
Thanks
Jeff