i don't agree with 20% having a few sailing boat since 1972
Like mainsail said
i have mine set to around 40 % to give it some relieve from full tensions witch extenuate life if cables by years.never had fr-ailing of woven s/steel cable
and it acts like shock absorber
But like many boats most rigging is done for a price .when you start replacing stays increase the cable load capacity by min 50% and set to max 40% load
You Will have a rigging that last for a long time and saving you maintenance
OK, this is really wrong in a number of ways. First, there absolutly no point in replacing your stays with bigger so as to "increase the cable load capacity by min. 50%" While you would have stronger cables, you wouldn't have stronger pins that conect the cable to the boat, stronger chainplates, or a stronger boat. Just to use some nice round numbers, if your boats stays have a capacity of 1000# and you increase that by 50% you would have cables with a capacity of 1500#. 40% of 1500# is 600#, or 60 percent of the original cables. Your boat wasn't built for that kind of prolonged static load. I'm pretty sure the Naval Architech that designed you boat spec'd it to have the cables it does for a reason.
Do a bit more research and I'm sure you will find G-'s recommendation of 15-20% is correct.
hunter Legend 37 Semper Paratus
Formerly - Tartan 34C Yawl