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Discussion Starter #1 (Edited)
Have a quick question on running duel backstays. Our boat is a masthead rig so a single backstay is adequate but I was considering running a single and then splitting off into two separate lengths of cable to the quarters of the stern to make is easier to access our stern entry and swim platform. Not a big deal either way, just curious as to whether this is ill advised for some reason. It will add cost to the rigging which is to be avoided but I don't think it should affect tension of the backstay or load distribution. I believe I've read that this can improve lateral mast support, acting as minor shroud supports, makes sense. Any ideas?
 

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Plenty of boats are set up this way... biggest concern would be your 'engineering' of the new chainplates for the split backstay. I don't think there's any structural support gain as you suggest, but it does allow you to add a easy, inexpensive backstay tension system by squeezing the two halves together.


OTOH, with a stern ladder and NO open transom, a fixed center backstay gives you something the grab on the way up.
 

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Re: Duel Backstays

Our boat is a masthead rig so a single backstay is adequate but I was considering running a single and then splitting off into two separate lengths of cable
That's typically called a split backstay. Pretty common, and as long as you have outstanding structural reinforcement where the new connection will be, you should be fine.

Not a big deal either way, just curious as to whether this is ill advised for some reason.
Make sure there are structural supports where the new backstay will connect to the boat. Lets say you have a 34' boat. A typical working load could easily be 1500+ lbs, and shock loads could be close to 3-4,000 lbs.

It will add cost to the rigging which is to be avoided but I don't think it should affect tension of the backstay or load distribution.
Nope it won't.

beleive I've read that this can improve lateral mast support, acting as minor shroud supports
I have never heard of this and don't quite understand the theory behind it? Do you have a cite I could check out?
 

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I did just that on my first boat (O'Day 23) . It worked out quite well . Main reason I did it was, I wanted a adjustable backstay. On the boat I have now It was a option so that you didn't have to have a boomkin .
 

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azguy: The way that your system works actually adjusts both of them. The split backstay is made out of a single piece of wire that is looped from the transom up to a wire block on the backstay, and back down to the multi-block purchase.

It is a nicer way of doing a backstay tensioner than the split system, but more expensive to implement.

This is a clearer diagram of what is going on:
http://www.harken.com/htmlassets/html/images/3896.png
 

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Discussion Starter #7 (Edited)
My only interest in the system was for ease of access from the stern, but after consideration I don't think that will really be an issue, and I don't think it will be a problem. To explain the lateral support theory (which I cannot cite) the idea is that anything run off ships center line from the masthead will have inherent lateral support, even if its only 30 degrees off center. As long as its symmetrically supported. With a standard forstay/backstay on center line there is no lateral support, mast can tip to port or starboard. With a duel backstay with two seperate stays running from masthead to stern quarters you gain a small amount of lateral support, obviously primarily carried by the shrouds. Its negligible but its there. Triangulation in any form offers support
 

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azguy: The way that your system works actually adjusts both of them. The split backstay is made out of a single piece of wire that is looped from the transom up to a wire block on the backstay, and back down to the multi-block purchase.

It is a nicer way of doing a backstay tensioner than the split system, but more expensive to implement.

This is a clearer diagram of what is going on:
http://www.harken.com/htmlassets/html/images/3896.png
Thanks, shows you what I know after 30 days of boat ownership. I'll have to say my PO spared no expense.....She's a real cherry...
 

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My only interest in the system was for ease of access from the stern, but after consideration I don't think that will really be an issue, and I don't think it will be a problem. To explain the lateral support theory (which I cannot cite) the idea is that anything run off ships center line from the masthead will have inherent lateral support, even if its only 30 degrees off center. As long as its symmetrically supported. With a standard forstay/backstay on center line there is no lateral support, mast can tip to port or starboard. With a duel backstay with two seperate stays running from masthead to stern quarters you gain a small amount of lateral support, obviously primarily carried by the shrouds. Its negligible but its there. Triangulation in any form offers support
Riggers generally don't recommend 2 separate backstays from stern to masthead as the tension cannot be equal, putting a load on the masthead that it wasn't designed to carry. I know Brion Toss is against this, and others as well. A backstay that is double at the transom and joins to be a single before continuing to the masthead has no such issues.
 

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Riggers generally don't recommend 2 separate backstays from stern to masthead as the tension cannot be equal, putting a load on the masthead that it wasn't designed to carry. I know Brion Toss is against this, and others as well. A backstay that is double at the transom and joins to be a single before continuing to the masthead has no such issues.
Thank you, that's good to know. A previous owner converted mine to dual backstays, I'll have to check to see how they're fastened to the masthead.
 

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For what its worth, we have a masthead rig with a split backstay. Single backstay attached to the mast, that splits somewhere above our boom. Not exactly sure at what length. This is how the rig was set up by the builder I believe, and not a modification made by a prior owner.
 

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I have the same split back stay on my Helms 27.. My problem is I keep banging in my head into the stay while sitting behind the wheel. Is there a way of adjusting the back stay at the "Y" that allows head clearance and does not compromise integrity of the rigging?
Thanks for any replies. Bill
 

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It would be easy to move the split point up the next time that you have a backstay made. You could shorten the existing backstay and make two new legs for the Y, but for slightly more money you'd be able to just replace the whole thing.

The backstay is split on my boat to allow access to the boarding ladder. The split is about 8' over the transom bench. There is no bumping your head on it, I can't even reach it.

The downside of putting the split up high is that a backstay adjuster car won't move upwards (towards the split) on it's own. I have to use a boat hook to get it all the way to the top.
 
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