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Old 12-03-2011, 18:18   #16
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Re: Backstay tension

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Originally Posted by s/v Jedi View Post
I'm sorry but don't agree with this at all. I have never met a rigger who states that slack leeward shrouds is okay. It isn't, and you will have to prove the world and her experts to be wrong before you can change accepted practice.
Wow...do you know a field of endeavour where all the experts agree? If so, must be an area where not a lot of expertise is required. I know enough riggers and have read enough of their tomes to be sure there is not one world view on the subject. And in any case, there is such a range of variables in any rig setup that no sensible rigger would make such a sweeping statement.

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Originally Posted by cabo_sailor View Post
?.. I've always gone by the standard that the lee shrouds should be just a tiny bit loose in about 15kt on a beam reach...I do notice some fellow sailors at my dock whose shrouds are actually floppy on both sides while tied to the dock. A conundrum, I disagree with that but what the hey it's their boat.
I agree that "loosish" leewards at 15 knots is about right, and from that looser when heavier naturally follows. And I agree with your concern at floppy at the dock - I've no understanding why anyone would think that's the go (but no doubt they too have a theory).

Here's a quote by Henderson (1985), who is at least expert enough to be in print: "...you should consider the effects of rig tension on the hull. Bar-taut shrouds can cause hogging, and a heavily tensioned backstay can bend up the boat's ends, possibly cause the forward or after end of the keel to separate from the hull, and even crush the mast step or push down the cabintop...Don't tension the rigging anymore than it needs to be to do its job, and slack off the backstay (in dock). Generally speaking, cruisers need only carry their rigging snugly enough to prevent EXCESSIVE movement of the mast in a seaway..."

In my experience, a rig thus tensioned will ALWAYS have slack in the leeward stays in moderate conditions and up. And that is the compromise I have judged right for my boats.
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Old 12-03-2011, 18:23   #17
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pirate Re: Backstay tension

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Originally Posted by At sea View Post
Wow...do you know a field of endeavour where all the experts agree? If so, must be an area where not a lot of expertise is required. I know enough riggers and have read enough of their tomes to be sure there is not one world view on the subject. And in any case, there is such a range of variables in any rig setup that no sensible rigger would make such a sweeping statement.



I agree that "loosish" leewards at 15 knots is about right, and from that looser when heavier naturally follows. And I agree with your concern at floppy at the dock - I've no understanding why anyone would think that's the go (but no doubt they too have a theory).

Here's a quote by Henderson (1985), who is at least expert enough to be in print: "...you should consider the effects of rig tension on the hull. Bar-taut shrouds can cause hogging, and a heavily tensioned backstay can bend up the boat's ends, possibly cause the forward or after end of the keel to separate from the hull, and even crush the mast step or push down the cabintop...Don't tension the rigging anymore than it needs to be to do its job, and slack off the backstay (in dock). Generallynspeaking, cruisers need only carry their rigging snugly enough to prevent EXCESSIVE movement of the mast in a seaway..."

In my experience, a rig thus tensioned will ALWAYS have slack in the leeward stays in moderate conditions and up. And that is the compromise I have judged right for my boats.
Thats why they're known as 'Banana Boats' mongst certain folks...
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Old 12-03-2011, 18:32   #18
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Re: Backstay tension

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Originally Posted by At sea View Post
I agree that "loosish" leewards at 15 knots is about right, and from that looser when heavier naturally follows. And I agree with your concern at floppy at the dock - I've no understanding why anyone would think that's the go (but no doubt they too have a theory).

Here's a quote by Henderson (1985), who is at least expert enough to be in print: "...you should consider the effects of rig tension on the hull. Bar-taut shrouds can cause hogging, and a heavily tensioned backstay can bend up the boat's ends, possibly cause the forward or after end of the keel to separate from the hull, and even crush the mast step or push down the cabintop...Don't tension the rigging anymore than it needs to be to do its job, and slack off the backstay (in dock). Generally speaking, cruisers need only carry their rigging snugly enough to prevent EXCESSIVE movement of the mast in a seaway..."

In my experience, a rig thus tensioned will ALWAYS have slack in the leeward stays in moderate conditions and up. And that is the compromise I have judged right for my boats.
I guess this would depend on the construction of the boat. If a boats hull were light weight then less tension would be more desirable but how about a steel hull or ferro cement. And 1985 who knows what he was talking about. It could have been wood.

Most rigging is relative to the design. Personally, I wouldn't want any shroud slack unless the boat were heeled at 30º+ on a close reach, then it would have an excuse.

Each boat is different and I'd be talking to the manufacturer rather then guessing.
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Old 12-03-2011, 18:34   #19
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Re: Backstay tension

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Originally Posted by boatman61 View Post
Thats why they're known as 'Banana Boats' mongst certain folks...
Can't find the actual clip but here's a commentary on the most expensive banana boat ever - the result of too much excitement in the rig tensioning department



Posted by a Kiwi of course... :-(
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Old 12-03-2011, 18:43   #20
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pirate Re: Backstay Tension

Its not guessing...
one of the biggest problems in the UK where small boats were designed without compression posts to create more useable comfort below was overtensioning....
80% broke the support beam through over tensioning...
usual evidence... compression post... careful look... repair job.
As has been stated... some have even had the top deck ripped open in weather..
"Think like Bamboo Grasshopper".....

Just saw the Video.... Brilliant
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Old 12-03-2011, 19:28   #21
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Re: Backstay Tension

Hmm I got distracted so didn't address the OP at all. About the backstay tension: It does 2 things: 1) tension forestay and 2) trim mast.

Before tuning this: understand that this has nothing to do with the rake of the mast. Changing the rake means changing the position of the foot of the mast on it's step and the kegs where it passes the deck, in addition to fore- and aft-stays. We're bending/straightening the mast when only adjusting fore- and aft-stays, not raking it.

We would need a complete description of your rig to describe how to tune it but basically you tension the backstay until the sag of the jib is how you want it. If the mast gets bend too much for that or if you can't tension it further (I would not tension it beyond 20% of breaking strength), your forestay is too long. If the jib sag is okay but the mast is upright and pumping, the forestay is too short. But an inner forestay and baby-stay (or forward lowers) complicate things.

There are good books incl. the free on-line one mentioned here before that you can use to look up your type of rig and find tuning instructions.

cheers,
Nick.
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Old 12-03-2011, 19:42   #22
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Re: Backstay tension

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Originally Posted by At sea View Post
Wow...do you know a field of endeavour where all the experts agree? If so, must be an area where not a lot of expertise is required. I know enough riggers and have read enough of their tomes to be sure there is not one world view on the subject. And in any case, there is such a range of variables in any rig setup that no sensible rigger would make such a sweeping statement.
Well, they do. You really want me to start quoting them? Why don't you quote one.. a single one, who states it's okay to have your leeward shrouds flopping around. Depending on type of rig, capshrouds should be tensioned to 10-20% of breaking strength. You should not just limit mast movement enough to not loose your mast... you should tune it so as to create the biggest safety margin possible.

I also noted that you wrote that you decided for yourself that it wasn't needed to tension your capshrouds... you did not point to a source or rigger telling you so. Your quote of Henderson is not about rig tuning but just some general remark that I agree with as it's all about the definition of "not bar taut". But if that is the rig tuning instruction then it's worthless.

cheers,
Nick.
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Old 13-03-2011, 19:04   #23
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Re: Backstay tension

Quote:
Originally Posted by At sea View Post
Can't find the actual clip but here's a commentary on the most expensive banana boat ever - the result of too much excitement in the rig tensioning department



Posted by a Kiwi of course... :-(
Gee, the things us Aussies do when we are being beaten. It is a bit like smashing ya tennis racket on the tennis court. If ya ain't gunna win, ya may as well do something to get in the history books.

And I like the discussion on shroud tightness as I had been wondering about my own boat, so thanks for the discussion.
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Old 13-03-2011, 22:55   #24
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It might be a side of the pond thing here but rake is the angle of the mast to the deck.

So yes just adjusting the forestay/ backstay will bend the mast and can change the rake of the mast. If you adjust all the stays/ shrouds you can easily change the rake off the mast without moving the bottom of the mast.

Moveing the bottom of the mast is another way to change the rake. That I believe is normally left to racer types on smaller boats.

Why do racers adjust the back stay when going up wind?

Yes to increase forestay tension but also as the wind increases primarily to bend the mast and depower the main.

As for shroud tension, as the video above points out, you have a choice in effect.

Over tighten rigging, damage boat due to stress on hull.
To loose a rig damage rigging due to causes so loudly mentioned above.

Some cruising boats are over rigged by a fair margin (previous owners did on mine). So loading up the rig to a percentage of the stays breaking strain would cause trouble.

Like anything on boats look at what your doing think about the cause and effect. If in doubt ask, read books and see how many conflicting opinions you can find
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Old 15-03-2011, 02:17   #25
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Re: Backstay Tension

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It might be a side of the pond thing here but rake is the angle of the mast to the deck.

So yes just adjusting the forestay/ backstay will bend the mast and can change the rake of the mast. If you adjust all the stays/ shrouds you can easily change the rake off the mast without moving the bottom of the mast.

Moveing the bottom of the mast is another way to change the rake. That I believe is normally left to racer types on smaller boats.

Why do racers adjust the back stay when going up wind?

Yes to increase forestay tension but also as the wind increases primarily to bend the mast and depower the main.

As for shroud tension, as the video above points out, you have a choice in effect.

Over tighten rigging, damage boat due to stress on hull.
To loose a rig damage rigging due to causes so loudly mentioned above.

Some cruising boats are over rigged by a fair margin (previous owners did on mine). So loading up the rig to a percentage of the stays breaking strain would cause trouble.

Like anything on boats look at what your doing think about the cause and effect. If in doubt ask, read books and see how many conflicting opinions you can find
Well said Onesea. That's what rake is down here too and the rest is wise counsel.

And for the OP, the last para is the most important. The real fun in boating is in figuring things out for yourself rather than relying the opinions of others. Cycles of reason and thought and testing will give you more confidence in your settings than adopting someone else's formula ever could. So tighten a bit, go for a test sail, look and think, maybe tighten some more and, as Onesea says above, always think about cause and effect, compromise and balance.

These boaing things will always intrigue, if you let them. Good luck.
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Old 15-03-2011, 03:42   #26
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Re: Backstay tension

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Originally Posted by At sea View Post
I knew that reply was coming sooner or later - that's why I said "others will contest this post"

It's true us boaties are an opinionated bunch but I'd suggest saying that your opinion is "different" rather than another poster's opinion is "completely wrong".

In this case, I have heard that theory, considered it and, on balance, decided to discount it. Others have gone through the same process and accepted it. It is one of those eternal club bar debating issues.

Unless you have some compulsive scientifically supported evidence with which to put the debate to rest, then I'd suggest that your position is just supposition - albeit not without fair (but contestable) reason. And even if that supposition is correct, then remember you must also consider the other implications of having the rig tight enough to prevent such leeward slack in conditions moderate and above.

It's best I reckon that we present our views and let the OP put it into the great melting pot of responses. That way at least the mystery of all things boating is not artifically simplified by the inference that there is a right and wrong answer to everything.
Methinks it is better to present our actual experiences to the OP as opposed to just views, and then let him decide.

I cannot quote someone elses scientifically based theory - preferring to present my experiences.

Factual I've only been sailing (both racing and cruising) for 30 years. I've only ever built one boat from scratch. I've only ever replaced rigging on three others. And I've only sailed some 50,000 miles. But I was always keen enough to tune my rig each year, and always open to expert views which invariably I would try out before adopting it as standard practice.

As a result I would not sail a boat with loose leeward standing rigging.

Twenty years back we did have a fast race boat, not new, but trimmed to sail with loose leeward stays. It was a slender fractional rig - in line spreaders - adjustable backstays etc.

It was a race winning boat so I went with the old skippers set up for the first month, and actually sailed four races with his recommended loose stays - only to watch them unstrand at the swage points.

My son was involved with AC boats locally so I took the chance to take quality advice as we re-rigged.

We never sailed with slack rigging since.

And proved its worth many times over. I can recall relatively recently matching up on a long haul race with a same model boat and seen our properly set rigging get us home not just in front but all intact. Whilst the same but softer rigged boat came in behind carrying damage.

Sorry, but this is all fact and not just a theory. Hopefully the OP will find this useful as it is not just an opinionated view.

Cheers
JOHN
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Old 15-03-2011, 04:57   #27
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Re: Backstay tension

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Methinks it is better to present our actual experiences to the OP as opposed to just views, and then let him decide
if you read my posts, John, you'd see that we may well agree that the best information is that which has come via careful thought, reason, testing and observation. My problem is with those who merely quote one 'expert' or another as the 'authority' and discount views (gained through such experience) which cannot be thus footnoted.

That your experience has formed your views I do not contest, nor do I contest the veracity of your views. I merely suggested that it's unhelpful to declare another poster's view (whoever's) as "completely wrong". People who have spent much time thinking and reasoning boating usually concede that they know just enough to know how little they know (aka: the more you know, the less you know). It's usually the relative newcomer who displays black and white confidence about such issues - of them we say that they "know just enough to be dangerous".

A final word about the attempt to distinguish between 'views' and 'experiences' as in the snip above. Really cobber, that's just semantics. If you read my posts, I am all for personal discoveries in boating. I think that's where the fun is. I only take issue with those who imply that there are simple formulae, right and wrong, black and white, smart and stupid etc, because it's too limiting and because it devalues the mystery and the intrigue of it all.
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Old 15-03-2011, 05:46   #28
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pirate Re: Backstay Tension

Bar Taut = like a rod...
a tad off = when you can hook a finger round the wire and it'll move an inch or two towards you with the strength of your arm.. not your weight.. and equal as near as possible all round...
As has been said above its a trial and error thing... it works for me...
and in all the years I've only had one wire pop on me..
and that was suspect before the voyage started.. otherwise having that touch of slack on the lee shroud is no bad thing.
Flapping around... not good...
but that should be self evident... as common sense should dictate if its that loose its not keeping your mast consistantly vertical at all angles...
To the 'Book Brigade'... my apologies... can't give lbs/sq"... don't use a guage... just my senses...
To anyone else... just because it works great for me... don't mean I'm right...
its your boat do your own thing...
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Old 16-03-2011, 19:36   #29
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Re: Backstay Tension

Good, sensible advice boatman; no tension gauge required, just a crooked index finger and common sense.

But no-one should be afraid to test the range of options because, in boating, the only thing entirely wrong is to see something as entirely wrong.
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