Are backstay adjusters a threat to B&R rigs?

[Arlyn Stewart]

B&R rig

Fred, your defense of the use of a backstay tensioner on a B&R rig is not without some merit. For example, if one is working offwind in a strong wind under headsail only, the tensioner is great for hardening the forestay and depowering the jib. If the main is double reefed, the same holds true, the tensioner will depower the jib without significant adverse effect. With all sail up, backstay tension will depower the jib but power up the main and loosen the rig possibly to the point where it could experience mast pumping or possibly shock loading if the tensioner is not released when the boat experiences rolling or a hard jibe. I use one on my masthead B&R rig also... but within the limitations imposed by the B&R rig.It would be safer to tune a B&R rig for low power and not mess with a backstay tensioner. Many sailors understandably don't want to give up some on the fly rig adjustment, I join you in that but do so only because I think I understand what I'm doing and when I can do it. An inadvertant or unforseen miscalculation could prove me wrong however.

 

[henkmeuzelaar]

The fine line between reasoning and knowing

Sorry for the quandary, Fred. You are absolutely right that I KNOW relatively little about B&R rigs. Having sailed one particular B&R rig nearly 40,000 NM does not make anyone a real expert. After all, there is no way of knowing whether any of the things one did and the results one observed were representative for the broader universe of B&R rigs or simply due to chance and unlikely to be observed ever again! Alas, such is the nature of EMPIRICAL KNOWLEDGE. The more variables at work in a given situation, the more observations one is going to need in order to make any generalizations at all.Consequently, my QUESTION (see title of thread)was aimed at the handful of people within the USA who actually might have collected enough empirical data on the behavior of B&R rigs under various situations (including external forces introduced by backstay adjusters) to be able to make such a generalization. Since I did not get much response initially, I just made my question a bit more provocative. Then, lo and behold, Alan tells us what he heard Lars Bergstrom say! Yeah, I know it was only secondhand. However, the likelihood that these remarks might indeed have come straight from the horse's mouth was quite exciting to me. Although I do plead guilty to not having a broad empirical knowledge of B&R rigs I am not willing, however, to let that stop me (or anyone else) from trying to reason about fairly straightforward mechanistic phenomena, such as the mechanical forces created on the forestay or shrouds by increasing the pull of an adjustable backstay on the masthead. It was the outcome of that type of reasoning that made me aware of the inevitable slack produced in the upper shrouds. Combined with the general knowledge about the effect of loose uppers on mast stability, this was enough for me to ask the question which started this thread. Several of the responses, including Lars Bergstroms reported remark would appear to vindicate that concern, at least in my mind.Flying DutchmanPSThanks for asking about Rivendel. She does not appear to have suffered significant damage from cyclone "Ivy" and is currently getting her new ocean hatches (an upgrade already promised to her many years ago). In addition, two more dorade boxes will be glassed in permanently. Together with her new (already finished) hard dodger I am hoping that our planned 2004 trips within the Vanuatu archipelago will enable her to prove that she is ready to start the long upwind voyage back to Hawaii and the US mainland in the Fall of 2005. HM

 

[Steve O.]

great thread!

People weighing in with forethought. Nobody flaming anybody. This is what it's all about!I just want to reiterate that that not all Hunters have B

 

[David Foster]

Glad to hear about Rivendel, Henk

It must be a huge relief for you!DavidLady Lillie

 

[newly anonymous]

fraction concerns

My brain is still reeling from Alan's report that Lars B said that the rig was designed to have a forestay adjuster. If there's any point of concern I've always had with my fraction BnR rig it's the amount of sag in my forestay. The owner's manual (page 53 for H410) stipulates that the sails are designed for 14" of sag. Unfortunately, in high winds this becomes more like 24" of sag, and I lose the ability to point. So I tune out most of the sag to match for summer conditions, where 25 kts true is a typical day around here, and then in the winter end up with lee helm in light air when close hauled. The obvious answere would be to retune the rig every season, but with roller furling it's too much of a pain to have to adjust headstay sag every time the weather forecast changes. I end up controlling sag to some extent with jib halyard tension, but any sailmaker will tell you that this is a big no-no, especially with a dacron sail, because you'll stretch the luff. One obvious solution would be an adjustable backstay, but it seems to me that a better fix would be to have a jib built for less sag, and then tune the forestay to something around 6". Any thoughts?

 

[Fred Ficarra]

Henk, I would never question your empirical

knowledge. IMHO what we are trying to compare as equivalent, are in fact two different worlds. A backstay adjuster on a fractional rigged B&R, I'm sure, would create more problems than it solved based upon your observations. Perhaps running backstays would be of more use.John, that's a lot of sag! The first warning in my Harken manual was to control sag 'in a seaman like manner'. My manual effectively ordered me to use a backstay tensioner. If you are sagging two feet, furling your headsail can lead to such disasters as work hardening of swaggings and then headstay failure.

 

[Alan]

John, re: sag 14"

I hope you are just kidding about the 14" inches of sag, or do you mean 14" of draft, which is a whole different issue. If you really have that much sag in your headstay, you defiantly haven't tuned your rig correctly. I would suggest that you put a Loos gauge on the cap shrouds and bring the numbers up to .25 SWL of that cable.