# backstay adjuster



## TSOJOURNER

Can anyone give me some advice on choosing a backstay adjuster for my Cal 28-2? I need it mainly for club racing, and have narrowed the choice down to a mechanical adjuster (wheel type? fold out handles type?), or a block and tackle system (anyone have an idea of the best configuaration? likely cost?). Any help would be appreciated.


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## Guest

A block and tackle or split backstay is probably the way to go as adjustments can be made more quickly and has easier visual indicators for quick reference. Depending on the set up they should be cheaper than a turnbuckle with an adjsutment wheel. 

Jeff


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## TSOJOURNER

Thanks for your reply. Yeah, block and tackle is the way to go. Do you have any recommendations for the type of configuration? Right now, I don''t have a split backstay, but I guess I can get a rigger to put one on. Is a split stay essential, or can you stick with a single stay? I''m open to all possibilities but would like to keep the cost down.

Thanks a lot.


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## geohan

It may be possible to adapt a lever type boom vang and get by with the single backstay and chain plate. Assuming a masthead rig I would avoid any block and tackle rig that wasn''t fail-safe. The simplest rig would be a stout lever with its end shackled to the chain plate and the backstay fitting attached to the lever a few inches toward the other end. The "other end" would carry a three or four part tackle to a cleat on the stern quarter. You would have to work out the mechanical advantage needed. And it is IMPORTANT to make sure the total geometry didn''t allow unfair strains on the chain plate or any of the backstay fittings through out the entire possible range of lever movement. This is offered as a concept only. The engineering needed is up to you.


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## paulk

We use a block and tackle with a split backstay on our J/36. The 4:1 tackle pulls a pair of sheaves down the two split backstays, pulling them together to tighten them and bend the mast back. The power in this type of setup depends upon how high up the split starts. When it''s not needed, the tackle can be unrigged to allow passage through the spit backstay - very convenient for the transom ladder. It also doesn''t leak hydraulic fluid, and even if the adjuster were to break (not likely), the stay(s) would still be there to keep the mast up.


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## Guest

I would suggest that you avoid the lever setup. You typically don''t have the range of adjustment that a backstay adjuster needs and the custom fabrication of a lever able to withstand backstay forces would be quite expensive. 

Probably the easiest set-up for a boat without a split backstay would be a cascading set up where you have a single wire block hung on the end of the backstay. (The backstay will need to be shortened.) A wirerope then runs from a trianglar plate at the chainplate at the deck thru the block on the backstay. Depending on the size of the boat there would typically be another wire block hung on the end of the first wire rope and another wire rope that runs through that block and has a thimble in the end. Again depending on the size of boat there would typcially be a 4:1 up to a 6:1 purchase. This combo results in a 16:1 to 24:1 overall purchase. (On really big boats there may actually be a third cascade resulting in 32:1 to 48:1 purchase, but for example, my prior boat, a Laser 28, had a 16:1 and my Farr 38 has 20:1 purchase on their backstay adjusters which seem adequate.)

Garhauerer seems to have the best prices on the kind of low friction blocks that you are looking for.

Good luck,
Jeff


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## TSOJOURNER

Are you sure you don''t want to try one of these? I''ve tried all the other versions you''re considering. Believe me, the extra cost for a good Sailtec or Navtec is worth it. Looks neater, works better.

http://www.pyacht.net/cgi-local/SoftCart.exe/cgi-bin/pagegen.pl?U+scstore+xmts1056ff3ba63b+pr+sailt10SI.html


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## TSOJOURNER

Our local rigger also recommended a hydralic system, but at $1000 bucks installed, it seemed too expensive. I''m sure you''re right about the money, but I was trying to do this with about $350 or less.

Thanks,

Chris Foley
Cal 28-2
Morning Star


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## Guest

The real problem with hydraulics on a small boat, besides maintenance, is that they are hard to put on and off quickly. With a block and tackle system it is very quick to make repetitive adjustements.

Jeff


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## geohan

I guess that I would have to admit that a lever type backstay adjuster ins''t for everyone. I wouldn''t want to pay shop rates to have one built. I do insist however that a handy do-it-yourselfer could fabricate such a device that is capable, convenient, aesthetic and economical. Capability is foremost and you can get that for $15. Convenience and aesthetics are extra, a lot extra.
Cheers, George


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## dougc

I second JeffH''s recommendation for a cascading backstay. It provides more power than the pinching system. The Merit 25s in the SF area came with the pinching system and we''ve all moved over to a 48:1 cascade. 

Also, consider how much you need to bend your mast. I read in Conner''s book that the typical cruiser will bend their mast 1% of the total length. A racer will push it to 1.5%.

If you''re NOT bending your mast that much, you''re throwing away a lot of potential draft range.

Also, when it comes time to order a new main, find a sailmaker that will measure you mast bend at off, half, and full on backstay tension. It takes about 2 hours to do this, but your mainsail will play like a Steinway piano.

Douglas Chew
s/v Challenger
Berkeley, CA


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## geohan

As an alternative to trying to bend a stiff mast for mainsail draft control, have any of you seen or used a system having nearly parallel lines of gromets just abaft the luff with a lacing line to gather in the excess draft much like a draft control zipper along the foot? I''ve read about it somewhere and have wondered how well it might work or if it is even racing legal. It seems like it could allow for a lot of draft control.


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## Jeff_H

I have used lace lines on small traditional boats. The problem, even on a small boat is that you really cannot precisely control shape as the stretch in the line, friction at the grommets and inability to evenly distribute the tension results in an irregular distribution of the flattening. There were some sails made with a zipper foot, or luff back in the 1970''s but this was not all that effective and was a bear to engage in the kinds of big gusts that flattening is best at dealing with. Mastbend with a backstay adjuster is such an easy and incrimental adjustment that controls both the mainsail and jib at the same time, and is reasonably inexpensive to build, that I have a hard time visualizing the advantage of going to a lace or zipper luff. 

Respectfully,
Jeff


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## geohan

Jeff: Please suffer one more tug on this thread. Was your experience with lace lines that of attatching the main to the mast or were the lines solely on the sail itself? Can a STIFF wooden mast be bent safely and sufficiently to really flatten and depower the main sail? What would you think of a second luff rope (wire) sewn to the sail on a curve matching the desired mast bend (like an adjustable leach line)? Maybe I''m just behind the times but I do like to keep compression members in-column if I can. Thanks for your patience, George


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## Jeff_H

I am not sure that I understand where you are going with this. I have sailed on traditional boats that had the sails laced on and have had brails rigged to be able to reef the sail to the mast rather than the boom. The problem with both is that your are dealing with pulling in a lot of line in order to alter the shape of the sail. Even the equivilent of a flattening reef could easily be yards of line that needs to be overhauled between the tension that you would want on a higher wind beat vs the shape you would want cracked off in the same conditions. With the high frictions involved, hauling that much line in and distributing the loads sufficiently evenly between the area of the differing loads on each cringle that result from the different tributary areas of the sail, becomes a very difficult if not imposible problem. 

Beyond this you would be gather a turbulence producing bundle of sail right at the leading edge where clean air flow is most critical. 

While there is a tendancy to think of a mast as a simple compression member, the reality is that masts have almost always been bending members as well. The ability and propensity of a wooden mast to bend has been an safety component of traditional boat design for centuries. Mast flexibility as a safety valve was well understood on an intuitive basis as early as the mid-19th century and is reflected in sharpie an skiff rigs by the early 1800''s. 

Herreshoff''s understanding of role of mast bend was so acute that S-Boat designed in the first decade of the 20th century had a mast that was actually precurved for that purpose.
The first academic study of the role of mast bend on sailing that I know of occurs in Manfred Curry''s treatice on the Aerodynamics of sailing in the 1930''s. 

In other words, mast bend has played a key role in sailing rig design for a very long time. It is only in the late 1950''s, that you find rig design changing to masts so stiff that fore and aft flexing is reduced to an absolute minimum. This is partially in response to the artificial shift to masthead rigs that resulted from boats trying to beat the CCA racing rule. Masthead rigs require much higher rig loads and so also develop much higher compression loads on the mast. Buckling in aluminum spars became a very real concern. 

With the change in the racing rules, there has been a shift back to the greater efficiency of a fractional rig and to ''bendy'' rigs that can allow rapid, subtly adjustable, on-the-fly shifts in sail power. There is now quite a long track record on these bendy rigs as they first began to become popular in the mid-1970''s. While the more extreme cases have not proven to be extremely long lived, the more conservative bendy rigs, such as the J36 which also incorporated raked back spreaders and lowers to minimize pumping,have stood up very well indeed. Using an example of a boat that I know particularly well, the Farr 11.6 (Farr 38) The Farr 11.6 was designed around 1981 and has a very early very bendy rig. It depends on swept back spreaders and lowers to prevent over bending and pumping. Farr 11.6''s began racing in the South Atlantic out of South Africa in the early 1980''s. To this day they still race as a semi-one design class in the Capetown/Rio (comes in somewhere else these days) and some of these boats have been doing this race almost every running. This is a race known for its heavy air conditions. In talking to a fellow who was active in this venue, some of these early boats are just now replacing thier spars after 20 years. Given the very hard useage, pretty primitive design and workmanship on some of these spars, and the move to penalty chutes that these spars were never intended to live with, that is not unreasonable. When we had my spar down last year, (Mine has had 20 years of hard use) we found no signs of fatigue and franlkly the spar looks very good. Which is a very long way of saying that I really don''t think that mast bend offers any real problem in terms of spar durability or safety as long as the spar design is not taken to an extreme.

In other words, you are not behind the time, but are operating on a theory that was only popular for a very short period in the history of sailing rigs. 

Respectfully,
Jeff


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## geohan

Jeff: Thank you very much for your comprehensive reply relative to mast bending for draft control. I see the bendy rig in a new light now and really appreciate your time and effort. Thanks again, George


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