I worked as a Tech Writer for ESCO Corporation where I wrote Work
Instructions for Chain Inspections, and also other safety
and mechanical maintenance
material. ESCO used chains for everything, including moving huge ladles (6+ feet high/acrosss) full of molten metal with overhead cranes that rode
on crane ways. In other words, chain failure = death.
That being said, each chain had to be inspected for wear where it rides on the adjoining links. If there was 10% wear from original specs, the chain was taken out of service
The chain on our 1988 Norseman 400, (displacement 19,000 empty) was 300' of 5/16" G4 ACCO chain. It looked in about the same condition as your chain, but we thought better safe than sorry. After all, this is the braking system for our boat
, and I wouldn't drive a car without brakes.
I had the chain inspected. It passed, meaning there wasn't more than 10% wear on any link. Yes, EACH link gets inspected (or is supposed to).
Then I had a 3' section of chain cut off from the anchor
end and had it pull tested at a local chain company.
Our chain's working load limit is 3,900 pounds. It finally broke the shackle it was attached to at more than 10,000 pounds of pulling pressure. So the chain didn't break, the shackle failed. MORE IMPORTANTLY, the each link in the section of chain that was tested had what is called "even stretch". Each link was stretched the same amount.
Then, I had the chain hot dipped re-galvanized. Total cost, less than $400 for everything. It was significantly less expensive than replacing the whole chain. And knowing that the brakes are good on my boat
helps us sleep better at anchor.
We also use an appropriate weight-rated-sized shackle from chain to the 60-pound QCR anchor, have the chain secured to the boat's chain locker with a cut-a-way strap, and use a bridle
anchor to take the force off the windlass
Best of luck.