8mm 7x7 galivanized standing rigging for 32ft ketch?

[Stumble]

Rhum,

You sneak in a few questions so here goes... hopefully I won't miss any:

1) I would suggest looking at Dynex Dux for shrouds and getting rid of the wire completely. It saves weight, can be replaced underway if need be, is lighter, easier to work with, and I personally hate the way galvanized stuff looks/feels. On the other hand I am highly prejudiced in favor of this stuff so YMMV. However I feel it is a much more cost effective rigging solution than other options, and havs the added benefit that you can cary a spool of the line down below in the event a repai is needed. Plus the weight savings up high help keep the boat on its feet.

2) I would agree that galvanized wire under some size gets pretty crappy. The problem is the lack of area for the finish to apply, and the amount of material scratches remove. It is just harder to do a good job on small detail parts. I don't know that I would put this point at 8mm, but I do think of it as a sliding scale thing, the smaller it is the worse the galvinazation.

3) Going up a size adds a lot of weight up high on the rig which is always detrimental. It also will add a good amount of drag to the boat. It may also be problematic finding fittings that match your chain plates in the larger size of the wire.

[Brion Toss]

Hello,
The ratio of surface area to volume is a big factor in the strength of galvanized wire. The surface varies with the square of the diameter, as I recall, and the volume with the cube. So the weakening caused by galvanizing hits the smaller diameters harder.
Having said that, I believe we've skipped past your motivation, which is to, "... avoid surprise failure and easily see the condition of the rigging..." I don't see how that connects to the use of stainless vs. galvanized. The boat's needs trump yours, in this case. Run the numbers to determine the right size, for both masts. Do what the boat needs you to do.
Fair leads,
Brion Toss