[cmm]

I have a 45ft mast with double spreaders on a 40ft 1980's fibreglass sloop.

The mast has forward and aft lowers, plus a cap shroud. This cap shroud is so-called "discontinuous" - a single 3/8" wire runs from the deck chainplate to the tip of the first spreader. Upwards from the tip of this spreader there are two wires:
1) a 5/16" wire runs to (near) the top of the mast.
2) a 1/4" wire runs diagonally to the base of the upper spreaders (intermediate stay), starting with a turnbuckle at the spreader tip.

So, 3/8 wire into the spreader tip, and 5/16 plus 1/4 wires going out.

I am in the process of replacing my rigging wires using Sta-Lok terminals for all terminations (prev swaged). My question is whether it makes sense for me to upsize the 1/4" intermediate stay to 5/16".

I checked the breaking strengths of the three wires, and the 1/4 plus 5/16 combination comfortably covers the strength of the 3/8 from the deck.

The current rigging sizes were used when the boat was launched. Dockside comments suggest I change to 5/16", but a local rigger said he would just stay with the original, although he could not explain why 1/4 was used.

It is such a short stay that weight saving would not really be significant. You'd think that the 1/4" intermediate stay takes a smaller percentage of the load compared with the 5/16" cap shroud, but I'm not sure.

So, I thought I may pose the question to the rigging experts on this forum - why was 1/4" used originally and is it a good idea to upsize to 5/16" for offshore cruising?