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Old 31-03-2009, 16:21   #1
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Running Backstays?

...at least I think that's what they're called.

My boat has the usual type of backstay, going from the absolute top of the mast then splitting into two about six feet from the deck, and attaching to two points at the stern.

Then there's these other two stays, that attach about 3/4 of the way up the mast, just shy of the second set of spreaders, that attach to the deck at about 4:00 and 8:00:


(please pardon my dirty, dirty boat - this photo was taken before I took possession and she hadn't been scrubbed in a year or more!)

These stays are clearly adjustable, and the previous owner says that it's so they can be moved around. I'm at a loss though - what benefit is there to moving the stays around?

Quite frankly I find the rigging setup (ie blocks, a 6' line run 8" off the deck, and a cleat) to be inelegant at best, and a hazard to passengers. There's a half-finished project in one of the storage lockers, where a custom stainless lock/release lever system has been built but not installed, and I think eventually I will attempt this - but for now, I don't really understand the value of the backstays not being fixed?

Can someone explain to me why this is useful, bearing in mind that while I'm fond of going fast, I have pretty much zero interest in racing (aside from the post-regatta drinks!). On a liveaboard/cruising/pleasure boat, is it worth keeping these as adjustable at all, or should I just fix them permanently and reclaim the deck space?
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Old 31-03-2009, 16:26   #2
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The owner's manual for my Dragonfly 1000 says to ease the cap shrouds when at the dock, and tighten them incrementally for light, mid and heavy air.

The point is to avoid unnecessarily straining the rig, while also avoiding slack leeward shrouds in heavy air.


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Old 31-03-2009, 17:19   #3
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I installed similar running backstays to back up my cap shrouds when sailing downwind offshore. They were an exercise in redundancy in an offshore saliing catamaran. I don't know if they saved my mast, but I will say that in our circumnavigation, the only original rigging that survived the trip was the cap shrouds that were backed up by the running backstays. All other standing rigging was replaced in various ports around the world.
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Old 31-03-2009, 18:23   #4
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As Dave says, they take strain off going downwind. Particularly if you get stopped by a wave, and the apparent wind suddenly goes above what you are reefed for.

Most running backstays connect where the forestay comes into the mast to keep the forestay tight, reducing sag and improving upwind performance of the jib. On monohulls with very light masts, you sometimes see an additional backstay coming from an unstayed section of the mast. I presume these limit pumping and fatigue.
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Old 31-03-2009, 18:32   #5
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Forgot to say - for monohulls with a bendy mast - pressure on the backstay, boom vang and Cunningham is also used to flatten the mainsail when going upwind. Can help pointing & depower a little, particularly when slightly over-powered.

Not sure how this works on multihulls where the stay comes in at a wider angle ...
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Old 01-04-2009, 08:50   #6
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Traditional running backstays lerad from the masthead to the stern on both sides of the boat. Lower shrouds, meant mostly to keep the mast in column, are fixed. Your rig seems reversed. The idea of an adjustable backstay is to carry the loads of masthead sails AND to bow the mast slightly forward to flatten the main when hard on the wind. I see no advantage of your set up except to ease the load or keep a bendy mast straight. That is, unless they are there to control mast pumping, a sort of hip shimmy that can very quickly fatigue a mast.
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Old 01-04-2009, 09:27   #7
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Pretty tough to answer without more info.

Does the rig have sweep to the spreaders? How much sweep? I would guess these runners are there to support the rig when running deep since it does not have sufficient sweep. These must be full adjustable to allow the main out when deep. Heavy air jibes should be fun.

Does the mast head have a crane? If it does not have a crane there is no bend induced by the runners, the crane is an eccentric that bows the rig. No crane, no bow.

Is there an intermediate on the runners going to a center location on the mast? If there is no intermediate (check stay) then the mast can pump and this runner will not help in that regard.

What is the D1 configuration? D1 afts? D1 centerline? D1 forwards? Is there a babystay or innerforestays? Is it a rotating spar? Does it have diamonds to support the panel? Does it have jumpers?

In my opinion I would not change the rig around until I fully knew how any move would impact rig stability.

Maybe more pics? Like I said, pretty tough to answer inteligently without more info.

Quote:
Originally Posted by drew23 View Post
...at least I think that's what they're called.

My boat has the usual type of backstay, going from the absolute top of the mast then splitting into two about six feet from the deck, and attaching to two points at the stern.

Then there's these other two stays, that attach about 3/4 of the way up the mast, just shy of the second set of spreaders, that attach to the deck at about 4:00 and 8:00:


(please pardon my dirty, dirty boat - this photo was taken before I took possession and she hadn't been scrubbed in a year or more!)

These stays are clearly adjustable, and the previous owner says that it's so they can be moved around. I'm at a loss though - what benefit is there to moving the stays around?

Quite frankly I find the rigging setup (ie blocks, a 6' line run 8" off the deck, and a cleat) to be inelegant at best, and a hazard to passengers. There's a half-finished project in one of the storage lockers, where a custom stainless lock/release lever system has been built but not installed, and I think eventually I will attempt this - but for now, I don't really understand the value of the backstays not being fixed?

Can someone explain to me why this is useful, bearing in mind that while I'm fond of going fast, I have pretty much zero interest in racing (aside from the post-regatta drinks!). On a liveaboard/cruising/pleasure boat, is it worth keeping these as adjustable at all, or should I just fix them permanently and reclaim the deck space?
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Old 01-04-2009, 09:31   #8
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Doesn't everyone? Our caps in racing trim are 40,000 pounds, in cruising mode we set them to 30,000 pounds. Otherwise the furniture moves.

Quote:
Originally Posted by senormechanico View Post
The owner's manual for my Dragonfly 1000 says to ease the cap shrouds when at the dock, and tighten them incrementally for light, mid and heavy air.

The point is to avoid unnecessarily straining the rig, while also avoiding slack leeward shrouds in heavy air.


Steve B.
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Old 01-04-2009, 09:35   #9
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as to the question of moving them...

Quote:
Originally Posted by drew23 View Post
These stays are clearly adjustable, and the previous owner says that it's so they can be moved around. I'm at a loss though - what benefit is there to moving the stays around?
...people will often move their runners forward, near the mast, in order to "store" them in light air when they're not needed to keep the mast from pumping.

BTW, your intuition that they might be hazardous to crew and passengers is spot on. Google on the term "Koch block" and you'll discover how a runner block knocked skipper Bill Koch silly during an America's Cup regatta. We used to call them head knockers, but ever since then they've been called Koch Blocks.

Bottom line: runners are evil. Racers like them because it's one more thing to tweak, which means they'll benefit the better crew. The rest of us realize that there are far better ways to prevent a mast from pumping, beginning with swept spreaders.
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Old 01-04-2009, 12:44   #10
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No crane is needed to bow the mast on a fractional rig.
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Old 01-04-2009, 14:44   #11
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True enough, I assumed mast head rig. Guess we'll have to wait and see what more there is to the story.

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Originally Posted by sandy daugherty View Post
No crane is needed to bow the mast on a fractional rig.
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Old 01-04-2009, 15:11   #12
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ok, sorry - I'm still a n00b sailor, most of my sailing has been dinghys. I have no idea what you mean by D1, rotating spars or jumpers...

Here's some more pics of the rig - I really don't know that much about it, so whatever you can tell me is helpful, I'm learning!



here's a bigger photo of her stern, with the stays visible - I'll link instead of embed, 'cause it's pretty large: http://mux.ca/boat/tiefighter-stern.jpg
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Old 01-04-2009, 15:25   #13
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Drew,
Searunner tris were pretty simple and straightforward designs, and all this talk of bendy rigs and so on is out of place IMO. A look at your pix shows that you have an inner forestay on which you can set a staysail. The main purpose of your runners is to help keep the mast straight when using said stays'l, especially when going to windward. If you don't use the runner, the mast bows forward from the loading of the inner stay, and this lets the luff of the stays'l sag off, and this in turn impairs performance.
So, for most sailing you can unhook the runners and lead them forward, out of the way of the mains'l. Incidentally, in case this hadn't occured to you, when sailing using the runner, only the windward one is set up tight. The leeward one is released and moved forward so that it does not interfere with the mains'l.

On our boat (a fractional rig with runners) we can leave both of them set up when we have 2 or more reefs in the main because then the main clears the stays. This gives extra support to the mast in heavy going, and I bet that your boat is the same.

Hope that this has helped,

Cheers,

Jim
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Old 01-04-2009, 15:32   #14
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Ok, so it's a mast head rig with in line double spreaders and an inner forestay for canvas.

The stays (runners) you identify support the inner forestay, Those are there so you don't pull the panel out of column when flying canvas from the inner forestay.
The boat has a permanent backstay without a crane at the masthead so you can't bow the rig with the back stay hard.
The d1s on center are the lower diagonal stays.
You have a permanatly fixed mast, not rotating.
There are no diamonds for panel stiffness or jumpers like you see with a frac.

Should be a good solid rig but you must keep the running backs.

Does that answer the question?



Quote:
Originally Posted by drew23 View Post
ok, sorry - I'm still a n00b sailor, most of my sailing has been dinghys. I have no idea what you mean by D1, rotating spars or jumpers...

Here's some more pics of the rig - I really don't know that much about it, so whatever you can tell me is helpful, I'm learning!



here's a bigger photo of her stern, with the stays visible - I'll link instead of embed, 'cause it's pretty large: http://mux.ca/boat/tiefighter-stern.jpg
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Old 01-04-2009, 16:12   #15
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Good thread and amazing that it was all the way to the 13th post from Jim Cate for the right answer!!

So, indeed, they are only needed when sailing with the staysail or if you feel the conditions are so bad that you want to support the mast more (but it shouldn't need that help...)

ciao!
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