Hi Gary , T Y , for bringing this ss failure to our attention.
I have never liked the “T”-bolt toggle design.
When I purchased my 9 year old , used boat in Honolulu, the stainless structural rigging was polished and looking good, so it passed survey with the recomendation that all ss structural fittings that spent their life in tropical salt water areas, should be replaced every ten years.
The first leg of my voyage to get her back home to San Francisco, was Honolulu to Seattle, in July, just as hurricane season was arriving. I was concerned, because this was my first solo long distance open ocean passage .
I had the mast pulled for re-painting, before my departure, and by accident, I found spider-web like cracks eminating from around the clevis pin holes on three of the mid-ship ss chainplates, Ouch !
The surveyor report hedged by saying that he couldn’t survey, what he could not see.
The spider-web cracks were covered up, by those ss bent plate “T” toggles .
My reasearch later showed that ss structural fittings needed to “shed” salt water, not entrap it, and go stagnant, or that chloride ion found in stagnant salt water, would start crevice corrosion .
Those bent plate “T” toggles were entrapping and holding the salt water right against the chainplates around the clevis pin holes, where you can not inspect, unless you remove them.
You are sooo correct that rust is evidence of corrosive activity in ss, and it needs to be stopped early or replaced.
I am glad that you are “Heads-Up” on this issue, and sharing your info with us, here on this forum .