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Old 01-01-2013, 21:28   #1
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Running Backstays

Hi Folks

Just bought my first sailboat after years of having sportfishing boats. She's a Cape North 43, Ted Brewer design built in Hong Kong 1980. I have an experienced advisor who has asked me to research whether we need running backstays. I have attached a photo showing the rigging with emphasis on the backstay which is split to port and starboard chainplates.

She is a cutter rig (formerly a ketch) and we have a storm jib and trisail for the inner stay. With the backstay split the way it is I would think this would give extra lateral support to the mast although as the stay comes directly aft from the mast this may not be true and perhaps the only reason the backstay is split is that it used to be a ketch. I've researched posts here on running backstays and their need in heavy weather running sails off the inner stay. There isn't a tang on the mast for running backstays. Did the designer preclude the need for running backstays by splitting the backstay?

We will eventually be doing some offshore cruising.

Thanks I'm learning a lot here.

Brian
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Old 01-01-2013, 22:03   #2
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Re: Running Backstays

I have had running backstays on two of my cruising yachts, and they helped keep the mast from pumping as much when sailing in heavy conditions when using the staysail and reduced main. I also like the additional support for the mast that could come in handy offshore if there is a rigging problem.

Except for weight aloft, the running back stays don't add that much complexity and were easy to fit on my boats.
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Old 01-01-2013, 22:11   #3
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Re: Running Backstays

Running backstays are not intended to give lateral support to the mast. They counteract the bending force imparted by the inner forestay and keep the inner forestay tensioned when you've got a sail on it. Split backstay has nothing to do with it. Aft swept spreaders, however, do create a similar force and might be a substitute for running backs depending on the geometry, and depending on the forces involved on the inner forestay. I would consult a good rigger if I were you. I would not personally want to use a storm jib on an inner forestay in a real blow, without running backs.
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Old 01-01-2013, 22:21   #4
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Re: Running Backstays

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Originally Posted by Dockhead View Post
Running backstays are not intended to give lateral support to the mast. They counteract the bending force imparted by the inner forestay and keep the inner forestay tensioned when you've got a sail on it. Split backstay has nothing to do with it. Aft swept spreaders, however, do create a similar force and might be a substitute for running backs depending on the geometry, and depending on the forces involved on the inner forestay. I would consult a good rigger if I were you. I would not personally want to use a storm jib on an inner forestay in a real blow, without running backs.
Agree.
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Old 01-01-2013, 23:45   #5
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The running back stays have nothing to do with the issue of whether the permanent back is single or split ( the backs may be split to suit the stern arrangement or can be used to tension the stay with blocks.

Definitely have running backs or check stay to support the staysail. I have a tall rig with a running back which is split at the top to support an inner jib and back stay.

Can be tensioned by winch/jammer or Highfield lever style device. I am sure there are many cruisers who abhore the whole notion of running backs but IMO they are not a big deal.
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Old 01-01-2013, 23:52   #6
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Re: Running Backstays

There are a couple reasons for split backstays. One is the center of the transom may have rudder stock in the way or lack of support for the force. Another may be that there may have been a pair of blocks pulling the split together creating more tension on the backstay for sail shape/stronger winds.

Also sugar scoop trasoms have a tendency to have spit BS.
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Old 02-01-2013, 00:53   #7
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Re: Running Backstays

The split backstay is to alleviate a conflict with the mizzen mast which is no longer there. If it were a double backstay that went all the way to the truck (masthead) then you would get some lateral support but not much since the lateral angle would be pretty small compared to shrouds.

From the line drawings (CAPE NORTH 43 sailboat specifications and details on sailboatdata.com) it appears this is a double spreader rig with the forestay attaching at the upper spreaders so the mast is adequately supported laterally.

When the boat pounds into waves the inertia effects of the mast, and stays and the sails attached to them cause the mast to pump fore and aft. These inertia loads are in addition to the normal loads from the tension in the stays and from the wind pressure on the sails.

At the masthead the forward pull of the headstay, sails and pumping loads is counteracted by the backstay. At the lower spreaders there are for and aft lower shrouds that resist the mast inertia loads, plus whatever sail and stay loads are transmitted down the mast from above.

At the upper spreaders the line drawing shows a fixed shroud that is out of the transverse plane of the mast, that does not run over the tip of the lower spreader, and that anchors at the same location as the aft lower. This type of shroud is not common, but it is not unheard of either. I do not recall if there is a specific name for this shroud. I assume there is also a normal intermediate shroud in the lateral plane of mast though I can't see this on the line drawing. The out of plane shroud will carry some fore and aft load but not much since the angle with the mast is pretty small, 2-5deg.

Since the line drawing does not show a running backstay and normally it would be shown I assume the mast was designed to be strong enough without one. Given that there are double lowers, the mast is probably pretty beefy and there are the out of plane shrouds carrying some of the forestay loads, I could see it working fine without running backs, especially in light and moderate weather. I personally would be more comfortable with running backs for heavy weather.

From the photo in the initial post I only saw one set of spreaders. It was not apparent if that was due to the perspective of the photo, or if there is only one set. If there is only one set of spreaders, then all bets are off.

Ted Brewer, the boat designer, is still alive as of several months ago though he has retired from most sailing activities due to health issues, his or spouse, I don't know. His website is still up though it has been 16mo since it was updated. I would try to contact him and confirm that the boat was designed for use of the staysail without running backs. The following is contact info from his site.
Ted Brewer Yacht Design
brewer@island.net
Phone 604-796-3732 Fax 604-796-3738
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Old 02-01-2013, 00:57   #8
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Re: Running Backstays

I Have running backstays on my 95 sunbeam 44 cc. It gives me a lot of peace of mind to run them with a storm jib if ever in a heavy blow. Also, they give me extra options if there is a, god forbid, rigging failure. I think that it´s worth the rigging costs of you are planning to go offshore. Make sure that you know how they work. It´s a given that you will need them in times of urgency. That is no time to be groping around.
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Old 02-01-2013, 01:44   #9
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Re: Running Backstays

Many many thanks for all the responses. I did send an email to Mr. Brewer to ask advice. If he responds I will add to this post. From what I read above running backstays are an important safety factor for offshore and are not expensive or difficult to rig.
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Old 02-01-2013, 10:17   #10
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Re: Running Backstays

Is anyone using Amsteel/synthetics for running backstays?
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Old 02-01-2013, 10:43   #11
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Re: Running Backstays

yes I have amsteel running backs 3 years and no issue. Use proper size eye block type at the eye splices.
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Old 02-01-2013, 10:43   #12
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Re: Running Backstays

Quote:
Originally Posted by delmarrey View Post
Is anyone using Amsteel/synthetics for running backstays?
Yup - still not in the water but have Spectra for the runners.
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Old 02-01-2013, 10:59   #13
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Re: Running Backstays

Quote:
Originally Posted by Dockhead View Post
Running backstays are not intended to give lateral support to the mast. They counteract the bending force imparted by the inner forestay and keep the inner forestay tensioned when you've got a sail on it. Split backstay has nothing to do with it. Aft swept spreaders, however, do create a similar force and might be a substitute for running backs depending on the geometry, and depending on the forces involved on the inner forestay. I would consult a good rigger if I were you. I would not personally want to use a storm jib on an inner forestay in a real blow, without running backs.
Running (or permanent) backstays supporting the use of an inner forestay keep the mast from bending forward. Swept back spreaders do the opposite and push the mast forward. right?
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Old 02-01-2013, 23:14   #14
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Re: Running Backstays

Quote:
Originally Posted by delmarrey View Post
Is anyone using Amsteel/synthetics for running backstays?
Yep, have used Dyneema 75 for our runners (and baby stay) for several years now. Being a fractional rig, our runners are in everyday use, and the Dyneema is much nicer than wire to deal with. This usage is quite common on modern race boats BTW.

Cheers,

Jim
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Old 02-01-2013, 23:50   #15
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Running (or permanent) backstays supporting the use of an inner forestay keep the mast from bending forward. Swept back spreaders do the opposite and push the mast forward. right?
Yes and no. Swept spreaders often make running backstays redundant. The shroud running over the tip of the spreader does push the mast forward. But every spreader has a shroud at its base which does the opposite.
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