Running backs

Running backstays attach to the mast in the same location that the cutterstay, or 'inner forestay', as some might call it, attaches to the mast. It is usually about halfway between the spreaders and the masthead on single spreader rigs, such as the Hans Christian 38 that I was up the mast on today.

Running backstays are called 'running' because they are moved fore and aft depending on which tack you are on, and are usually only employed while using the cutter (inner foresail, jib, etc.) to counter the strain put on the mast by the cutter sail. Most good running backs need to be snap-shackled to deck pad-eyes, but some actually run on tracks. Running backstays incorporate a block and tackle system like a boom vang, with cam cleats, to facilitate quick adjustment.

 

There is more to running backstays than that. I have them on my mizzen and they go to the mast head. They are "running" because they are not standing (think running rigging vs. standing rigging). Mine set up with a 4 part tackle to tension them (they are brought down to pad eyes on the stern corners) and the tackle leads to cleats at the cockpit (This is on a 39 ft. center cockpit ketch). They were designed to take the extra load of a mizzen spinnaker or mule.
In general they are used to add extra support where it is needed and yet be released to get out of the way of the boom and sail. There are always (at least in my experience) two of them so one can be tightened and the other released to get out of the way of the sail/boom. They are also very big in the big boat racing circles to help shape the mast and allow use of lighter weight spars. In that use they are typically very heavily loaded and a failure to get the new one set up in time (during a tack or jibe) can lead to loss of the mast.

 

Nice try Hawkeye, but the definitions and uses of a running backstay are somewhat broader than your post suggests and not terribly relevant to an Ericson 30+. Your answer isn't wrong its just not quite complete.
Starting with the broad generality, the normal backstay on most modern rigs is technically called a 'standing backstay' or 'permanent backstay'. Standing backstays may be adjustable but their geometry is such that they can remain in place during a tack.

A running backstay is a backstay that is not made up (kept tensioned) permanently, but must be eased or tensioned with each tack. Because of rig geometry running backstays are used in pairs, one on either side of the boom. When the boat is tacked the new windward running backstay must be tensioned and the new leeward runner must be eased. They typically originate at the hounds (where a jibstay attaches) and are typically run as far aft as possible. Some rig designs require the runners be used at all times to keep the rig up, while others only use runners electively for specialized purposes such a beating or heavy air.

Runners are used on gaff riggers where the gaff prevents rigging a standing backstay. They are used to maintain headstay tension on jibstay on a cutter. And here is the relevant answer to an Ericson 30+, they are used on fractional rigs to increase forestay tension. The Ericson 30+ is a double spreader, fractional rig with non-swept spreaders. Without swept spreaders or jumper struts, fractionally rigged boats tend to have a lot of headstay sag. Runners exert a pull aft tensioning the forestay and reducing headstay sag and thereby improving upwind performance.

Jeff

 

Thanks to all of you for your explanations. That all begins to make sense, but raises a few more questions as well (learning more is likely a good thing, I think...). Assuming the mast is not lightweight for racing, then given the answers above, a masthead boat with a properly tensioned permanent wire backstay shouldn't need running back stays--correct? And similarly, a fractional rig boat with a solid mast, and a permanent wire backstay would likely only need running back stays if it were in very strong winds or overpowered with sails, to counteract the pull of the headstay from it's lower position on the mast--ie. the permanent backstay would pull on the masthead, but running backstays may be needed a bit lower to offset the lower forestay attachment of the fractional rig--correct? And finally, with a solid mast, permanent wire backstay, and sailing in reasonable conditions with reasonable sail plan, running backstays would be unnecessary? Would the extra weight of a roller furler significantly increase the need for running backstays on the Ericson 30+, if the forestay is tensioned properly?
Thanks again for clarifying this.
Frank.

 

"Standing backstays may be adjustable but their geometry is such that they can remain in place during a tack."

I can't recall having to move running backstays during a tack?

My running backstays are attached to the mast where the inner baby stay comes off. I use it in really lumpy seas to stop the mast from flexing fore/aft and also if I fly a storm jib off the baby stay.

The rest of the time they're made off to the mast with the tackle in the lazerette.

 

http://www.sailnet.com/collections/...nce/index.cfm?articleID=ddcksn0517 &coll_cat=Spars&Coll_name=Spars and Rigging

 

Mast bend control.

all of these replies about runners are all in their own different ways correct. To put it as simply as possible, runners are used to help add headstay tension on fractional boats as well as control mast bend in all boats. On a masthead rig when you pull on the permenant backstay the mast bends forward flattening the main, now at some point the headstay will sag more due to the fact that since the mast is bending forward the distance between the deck and masthead gets shorter. Runners can be used to limit the amount of bend in the mast keeping the main fuller at the same time keeping the headstay tight. If you have a club for a mast there will be no need for runners as the mast cannot be bent that much to make it a concern.

 

Runnning backstays: these are lines attached to the mast, on a masthead rig at the spreaders (in the simplest case, usually the top set, if the mast has multiple spreaders). They run to the stern of the boat, one to port, and one to starboard, and typically then to a winches.

Often, running backstays are used to control the mast bend. On a masthead rig, they allow mast bend to be controlled independently of headstay tension. Typically when you add headstay tension by tightening the backstay, the main flattens, which de-powers things. Adding tension to the runner on the windward side straightens the mast up, and makes the main fuller.

Running backstays are fun if you like to tweak strings while sailing. They can make raising the main and tacking into major, tension-filled events if you are not careful.