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Backstay tension

Aug 7, 2019
1
Sirius 21 Hamilton
trying to rig up a old neglected girl and there seems to be quite a bit of slack in the backstay. Adjustments have been brought in to its minimum. Headstay and shrouds seem good. My question is how much tension should be in these stays and why can’t I adjust the slack any further in the backstay? Thanks all in advance
 

Joe

Jun 1, 2004
6,737
Catalina 27 Mission Bay, San Diego
Check the "rake" of your mast using the "plumb bob" method with a halyard. If you feel it could lean forward a bit without going past vertical you could put a few turns on the forestay to remove the slack from the backstay. That said.... fore and aft stays aren't as critical as the shrouds in keeping the mast straight. Many, many boats have adjustable backstay tensioners important to sail trim applications. On fractional rigs, where the forestay mast attachment is below full height, backstay tension is used to control mast bend, which is an important mainsail trim adjustment. For masthead rigs like Sirius 21, where the forestay attaches at the mast's full height, backstay tension is used to control forestay "sag".... which is an important headsail trim adjustment.
 
Oct 22, 2014
9,926
CAL 35 Cruiser Portland OR, moored EVERETT WA
There are several reasons for a slack stay.
  1. You may have connected the wrong stay to the past. Fore stay in the back stay position as an example.
  2. The mast may have sunk. If the mast step gets soft the mast will sink into the boat and the stay’s will go slack.
  3. Sometimes on a small boat you do not need to put high tension on the stays. Some boats actually sail faster with loose stays. Not sloppy but also not strung so tight you can hear High C. Think loose like a deep base.
  4. After years of service wire stay’s can stretch. Then it is time to replace them.