Baby Back Stays.

[windships]

My boat is a mast head rigged boat. The detachable staysail is attached to the uppermost non swept spreaders and secured via a hydraulic ram on deck. The baby back stays run down to a block on a track and have eyes at the end of the stays. My question is, -If I'm running the staysail, with or without the Genoa, how much trension do I put on the baby back stays, and how do I know I have enough? Do I eyeball the mast and make sure it's not an "S" shape? Can some one give me guidance on this please?

[swagman]

Hi Windships,
Afraid its impossible to give you an exact loading as it will depend on on how the rig is set up. How stiff the mast is, etc.
Basically you want to get the same loading on the running backstay as you have on the inner forestay to prevent the mast pumping at that point, and trial and error is as good a way of getting the right setting.
Just be sure once you've got it right (on boat sides) you mark the runners so you can repeat the setting easier the next time round.
A useful tip is to use a clear peice of transparent cellphane with a line drawn in back texta pen - that you can hold up and view through to be 100% sure you keep the mast straight.
We've had one lighter weight JOG flyer with a spindly mast, and runners adjusted using a block and tackle type arrangment. Those I just hauled as tight as I could - enough to stop the mast pumping at the forestay / backstay point.
Other heavier cruisers and bigger racers we've owned had their runners led to winches. Just be careful if this is you case as it is easy to overdo the tension with a winch - especially if electric. Look up the runner as you are cranking, and stop tightening when the mast looks stable.
Finally don't only use those runners when you are using the staysail on the inner forestay. If you are reaching / beating in heavy seas with the normal forestay in use, the runners can help keep that mast stable. Worth while if you can be bothered.
Enjoy
JOHN

[daddle]

"Whatever it takes to get the job done, and no more." This is what my mast builder told me. Just enough forestay tension for the conditions. Keep a nice curve aft in the mast at all times. Not much help, I know, but this is the rule.

[svHyLyte]

Originally Posted by windships

My boat is a mast head rigged boat. The detachable staysail is attached to the uppermost non swept spreaders and secured via a hydraulic ram on deck. The baby back stays run down to a block on a track and have eyes at the end of the stays. My question is, -If I'm running the staysail, with or without the Genoa, how much trension do I put on the baby back stays, and how do I know I have enough? Do I eyeball the mast and make sure it's not an "S" shape? Can some one give me guidance on this please?

A. A "Baby" stay is situated on the foward side of the mast and is a replacement for forward lowers.

B. "Running" Back Stays (AKA "Runners"; and, "Running" because one needs be able to let the leeward stay "run" freely so as to not impead the swing of the boom/mainsail) replace aft lowers and should be set up a tightly as necessary to keep the mast "in column", i.e. without any visible bends fore or aft between the partners and mast-head (although some bendy racing rigs may intentionally have a forward curve in the spar to flatten the main in some conditions). Ideally, the Runners should be affixed to the mast at or very close to the point of attachment of the removable forestay. On our yacht, in brisk conditions with a full main, we estimate about 1200 lbs on the weather runner. Our runners are 1/4" spectra passing around a turning block and forward to our secondary winches.

FWIW...

[windships]

Thank you all for the great advice!