I recently installed wires on a P18. How tense do they have to be? It looks like they are way more tense than the diamond wires. The latter touch the mast at 13" when pushed against it.
Next I loosened the spreaders a bit, and the leeward side is very sloppily dangling, but still the diamond wires get never tense.
if the p18 has a rotating mast then you want them as tight as possible but still have the mast self-rotate after a tack, the diamond wires are completely separate and have no effect of the stays and vice versa. ie you can remove the diamond wires from the mast and the stay tension will remain the same or when the mast is off the boat the stays have zero tension but the diamond wires still have the same
the leeward stay will always look loose when you are sailing. if you think it is too loose take the mast forward a hole on the forestay, if the mast still auto-rotates smoothly in tacks leave it there
/agreed
Tighten the forestay and shrouds as tight as they can be without hindering rotation at all.