I recommend you don't go by the chain, it may not be the right chain for your gypsy. I know that 5/16" BBB and HT chain are very similar in size and either would probably work. A previous owner could have selected the wrong type. Plus, chains lengthen from wear and corrosion, so measurements will not be a good indication.

contact the manufacturer of the windlass gypsy for guidance. I couldn't find the identification on my gypsy, but after talking with the rep, I was able to find it.