solent stay question
 

i realise that the solent stay should attach to the mast as close to the forestay attachment point as possible but is there some rule of thumb or calculation to determine what would be the maximum allowable distance (say as a % of mast height above deck or similar) between the solent stay and the headstay attachment points before running back-stays would be required?

Really - you ought to hire a naval archetitect to calculate the loads that stay (and associated sail?) will put on the rig, and how to support it correctly. its either that, or get well into some of the common works on rig design, like 'Skenes' and ' Riggers Apprentice'.
that said, if you stayed within 5% total mast length , then you are probably fine without additional sideshrouds or runners. probably.

thanks for the info

i found the following recommendation in the selden mast on-line catalogue (page 31): "(if) the cutter stay is located 3 - 6% of the height of the foretriangle below the existing forestay ... (then) ... running back-stays are not required"

www.seldenmast.com

since selden do not reference this to a particular spar section or rig design i guess it's as close as we'll get to a "rule of thumb" (given it comes from a manufacturer's documentation i suspect it is conservative)

the spar on "karen m" is from selden