I have a 1984 Hunter 34 with the swept back double laced spreaders. Has anyone had any success installing a backstay adjuster on this boat. And if so what amount of mast bending is really possible.
back stay adjuster
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On most cruising boats the backstay adjuster is intended to maintain headstay tension, not to bend the mast. Most boats with furlers suffer from deplorably loose headstays. It seems that many people forget about the headstay because it's inside that nifty convenient furler thing. But the weight of the furler extrusions and the sail that is always on there and even the Sunbrella sun cuff are all responsible for increased sag. In some cases the added toggles on each end of the wire necessitate a cutting of the stay itself and the result is a too-short headstay and, therefore, a lack of mast rake or even negative (forward-leaning) mast rake. I have seen this too many times to discount it.
The backstay adjuster will enable you to take up on the rig, drawing the sag out of the forestay. But, a word of caution-- electric and hydraulic systems (that race boats do use to bend the mast, if they are fractional rigs) can impose tremendous tension on the rig-- easily enough to puncture the deck at the mast step and do other unimaginable damage. Stick with a nice block-and-tackle system, even on a boat up to 37-40 feet, and otherwise maintain the standing rigging as it should be.
I am not a fan of much mast bending only because I know well the damage that constant cycling of stresses on aged aluminum can create. That said, I prefer to ease up the tension when the boat is put up for the night. I just don't like leaving it under load-- though it would make sense to tension it once and leave it, the use of a backstay adjuster means it's getting cycled plenty often already; so I doubt it matters much in the grand scheme of things.
My boat has a 4:1 purchase on the 4-wheel CS Johnson car riding on a split backstay. This year I am putting a block on the bottom of the car and running a leg over to the other corner of the transom to result in about 8:1 (4:1 pulling on one leg looped over another block), kind of a two-legged cascade system. It will be more powerful-- but really it is more to ease the load on my old arm and shoulder and back than it is to apply more tension. And I don't have a furler anyway and I typically nitpick the tuning of the rig the way I do that of a guitar.
The backstay adjuster will enable you to take up on the rig, drawing the sag out of the forestay. But, a word of caution-- electric and hydraulic systems (that race boats do use to bend the mast, if they are fractional rigs) can impose tremendous tension on the rig-- easily enough to puncture the deck at the mast step and do other unimaginable damage. Stick with a nice block-and-tackle system, even on a boat up to 37-40 feet, and otherwise maintain the standing rigging as it should be.
I am not a fan of much mast bending only because I know well the damage that constant cycling of stresses on aged aluminum can create. That said, I prefer to ease up the tension when the boat is put up for the night. I just don't like leaving it under load-- though it would make sense to tension it once and leave it, the use of a backstay adjuster means it's getting cycled plenty often already; so I doubt it matters much in the grand scheme of things.
My boat has a 4:1 purchase on the 4-wheel CS Johnson car riding on a split backstay. This year I am putting a block on the bottom of the car and running a leg over to the other corner of the transom to result in about 8:1 (4:1 pulling on one leg looped over another block), kind of a two-legged cascade system. It will be more powerful-- but really it is more to ease the load on my old arm and shoulder and back than it is to apply more tension. And I don't have a furler anyway and I typically nitpick the tuning of the rig the way I do that of a guitar.
Along the same line of caution Diana mentions is the fractional rig considerations. The backstay has to come off the masthead. On a fractional rig the forestay comes off the mast somewhat below the mast head. If you start tightening the backstay you impose a bending moment on the mast between the masthead and where the forestay is attached. Masts have to be designed to accept this kind of loading. Since you have swept back shrouds you also have to consider that bending back the mast will loosen the shrouds also. This could have some interesting (read not desirable) effects on the rig.
The 34 is masthead rigged, but also has swept back spreaders. On my boat we're talking 30°. So you do not want to bend the mast anymore than it already is by the B & R rig. I do have a block & tackle on the split back-stay, but as Diana and Bill mention I only use it to pick up the sag under heavy winds. I suppose I could tighten up the head stay even more, but it is tuned correctly for 90% of the conditions I sail in so it will stay as is ! Your 34 is likely to have the same configuration as mine so don't count on the tensioner to have any impact on the main as it would on a fractional rig.
Backstay adjustment on H34's...
Many of the H34's had a Hyde Streamstay furler installed for the headsail. You don't indicate which furler you have.
With the Hyde unit, the "foil" is actually the headstay itself. It is a stainless rod of substancial heft, not a thin metal extrusion over a wire forestay. Applying any more tension to it will probably not increase any more bending of the mast than has already been set in the pre-tensioning.
You could also risk pulling the system apart with too much tension, risking taking down the mast if that happens.
Many of the H34's had a Hyde Streamstay furler installed for the headsail. You don't indicate which furler you have.
With the Hyde unit, the "foil" is actually the headstay itself. It is a stainless rod of substancial heft, not a thin metal extrusion over a wire forestay. Applying any more tension to it will probably not increase any more bending of the mast than has already been set in the pre-tensioning.
You could also risk pulling the system apart with too much tension, risking taking down the mast if that happens.
Re: Backstay adjustment on H34's...
Thanks for bringing this up Dan. For clublunasea to be able to compare apples with apples and oranges with oranges, I should have also mentioned that my boat had a CDI furler and the back-stay adjuster when I bought it but I did not like the CDI and replaced it with a Profurl. At that time I also replaced the headstay. Both the headstay and upper part of the back-stay are 9/32 SS wire (7 X 19).
Thanks for bringing this up Dan. For clublunasea to be able to compare apples with apples and oranges with oranges, I should have also mentioned that my boat had a CDI furler and the back-stay adjuster when I bought it but I did not like the CDI and replaced it with a Profurl. At that time I also replaced the headstay. Both the headstay and upper part of the back-stay are 9/32 SS wire (7 X 19).
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