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Old 28-04-2015, 14:48   #1
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Boat: Alan Wright Hanii, 28ft masthead sloop bilge keeler, Celine
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Running backstays

Hi, I'd like to change my inner back shrouds to running backstays. This is to allow the boom to swing further forward when either running or coping with a squall. I sail single handed and thought that I'd build a set of "Highfield" levers to apply / release the backstay tension easily. My local foundry can cast them in aluminium bronze.
So here are the questions: Can I convert the inner aft shrouds to running backstays and how well does aluminium bronze survive in salt water.
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Old 28-04-2015, 17:21   #2
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Re: Running backstays

The practicality of the shroud conversion depends greatly on the specific rig design. It wuite possible be successful, but a competent rigger should be consulted.

Aluminium Bronze is the material of choice for propellers, and should do well in your application if the design is good and the casting well done.

Jim, using Ann's computer
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Old 28-04-2015, 18:04   #3
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Re: Running backstays

I'm not a competent rigger and I agree with Ann that you should consult one (or two).

In my experience running back stays have much less initial tension than a typical aft lower stay. And they are not at the same place on the mast. A running backstay wants to be landed on the mast at the same height as the inner forestay. A lower aft stay will not be that high generally. Does the Nanii 28 even have an inner forestay? I have not seen one of this design before.
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Old 28-04-2015, 18:07   #4
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Re: Running backstays

They are going to make the same job as the lowers, if you dont have some serious mast rake due to a tight inner forestay then could be fine, guess i have the same configuration as yours, aft lowers working like runners... Cheers.
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Old 28-04-2015, 20:16   #5
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Re: Running backstays

Thanks everyone.
It sounds as if the use of ali bronze will be OK.
Regarding the rigging. Celine is a masthead sloop with a roller furling headsail. Originally she had a single forestay and two inner aft shrouds. These all run to the deck from just below a single set of spreaders at halfway up the mast. The forestay used to be attached 2,350mm forward of the mast and the inners meet the deck 900mm aft of the mast. The mast is keel stepped and rises through the cabin top to 11,300mm above the deck. The mast is straight. The forestay has been removed to clear space on the foredeck. It has been replaced by two forward shrouds attached 900mm forward of the mast. The single backstay tension is set by a rigging screw and not adjusted during sailing. Celine has a 28ft OA glass over ply twin keel hull. With a 13HP Yanmar aux. She draws one metre and is rather heavy and somewhat tender. Still I like her and she will go where other won't.

Thanks for your comments. Joohn
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Old 28-04-2015, 21:02   #6
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Re: Running backstays

John,

Regarding the use of highfield levers, I am currently trialling the use of blocks with 4:1 purchase in place of our highfield levers.

Our levers have worked very well but they are big heavy things to have hanging around (literally) and quite dangerous in some situations.

It is too early for me to say for sure but I suspect I will settle on the blocks with dyneema line in preference. At the moment, and for the best part of a year now, the highfields have remained below decks in the rigging compartment.

If I could figure out how to do it with the iPhone app I would point you to the thread I started on the subject where I received some good advice. Perhaps you will be able to search for it. The title was probably pretty clear

Matt


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Old 28-04-2015, 22:25   #7
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Re: Running backstays

I thought that I could mount a set of over center levers on the deck outside of the cockpit but I should have taken a look at my drawing of the rigging first. It looks as if I need to take in too much line to do it with a permanently rigged highfield lever. I'll have to carry out a test to see just how much line I have to add to the shroud to let the boom swing out further as well as how to handle a running backstay on my own. Celine is due on the hard for some work and antifoul so I'll talk to a rigger then. Once again, many thanks
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Old 28-04-2015, 22:43   #8
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Re: Running backstays

Normally the highfields are combined with a block setup anyway, to help with this problem. They highfield itself should only put an inch or so of movement on the system as you noted. Without the block you would be needing some other method of setting the un-tensioned length as the rigging ages and stretches over time.

On the few highfield setups I have seen (not many), the highfields are detached from the chainplates and brought forward to a position out of the way of the boom, at which point they become big heavy clubs if they get loose, just ask around, it happens. I guess you could leave the highfield attached at the rear chain plate, and detatch the running backstay from the lever... but the lever would be clunking around and would need to be secured in some way, plus I am sure it would get in the way of something else, as is the way with boats.

Ask the rigger about a block setup, with a tricing line to pull the downwind backstay forward to the stays (Many many thanks to SnowPetrel for that hint). I sail our boat solo most of the time, and this setup is a breeze, much easier than the highfields. Certainly in our case, the dyneema line is doing as good a job as the highfields were, and the tricing lines mean I don't have to leave the cockpit on a tack, wheras I had to with the highfields to stow them "safely" foward.

My impression is that highfield levers have been made mostly obsolete by the availability of modern low strech rope.

Also, I just thought about it some more, and our setup is now 3:1 purchase from the blocks, plenty for our old rig.

Matt

P.S. Found that thread...

Maintaining Tension on Running Backstays
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Old 28-04-2015, 23:19   #9
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Re: Running backstays

Thanks Matt,
I had a look through the thread it's good stuff. I'll wait till I get onto the hard and have another think about the problem. It sounds that blocks are a better idea but they will probably have to be in the line of the existing aft shroud with the line running back to the cockpit and cam cleat.


John
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Old 29-04-2015, 00:03   #10
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Re: Running backstays

Quote:
Originally Posted by GILow View Post
My impression is that highfield levers have been made mostly obsolete by the availability of modern low strech rope.
I don't think the modern rope is the issue.

I think the weight is part of why highfield went away and the movement of the racing branch of sailing to sloops negating the need for running backs generally.

The third option I've seen is a ball bearing track and car on each side. The backstay lands on the car and as you pull the car aft you load up the stay. A 2:1 block pulling the car aft is probably all you would need to bend the mast to your heart's content. Lead a bungy from part way the stay to a block at the base of the aft lowers and then forward along the rail or up the lower to a tieoff point and the car will retract to it's stowed position as soon as you release the tensioning line.

The advantage of this over the block system is speed and ease of tensioning with less rope tail to deal with at the cost of more stuff on the deck and the initial expense.
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Old 29-04-2015, 14:31   #11
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Re: Running backstays

Hi Adelie,
From a force point of view that is a good idea. Pulling sideways on a line is an easy way of winding up the tension. A stop could be placed on the track so that the tension can never be less than some preset value.
This thread has developed because of my desire is to uncouple the inner aft leeward shroud and so allow the boom and main to swing further out before fouling it.
The previous owner has already replaced the forestay with two lower shrouds running forward of the mast.
My mast is very stiff but I still have to talk to a rigger about changing the lower shrouds.

Thanks, John
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