Chain Plate Sizing

[Brion Toss]

Hi,
I'd need to run the numbers, but the odds are good that the chainplates are the right size, and the wires not the right size. The uppers on your boat take about 45% of the total transverse load, so their chainplates should be thickest (along with the jibstay). The lowers share the balance of the load, so would see only a bit more than half of what the uppers bear. Likewise the backstay, which takes less load than the jibstay or uppers.
But really, either you or I or someone should make sure of the load magnitude and distribution before you replace those chainplates.
Fair leads,
Brion Toss