[KJ and I marking anchor chain lengths with electrical tape]
Our 5/16th BBB 100 foot chain came in! It is a brute! Perfect! After inspecting all the links, KJ and I sat down to measure off 20 foot lengths and to mark it.
There are many systems for marking chain, and there are plenty of "devices" you can buy to mark both the chain and rode. KJ and I marked the chain and rode with electrical tape. This approach will require maintenance (e.g. retaping periodically), but didn't cost us any additional out of the pocket money as we already had 5 colors of electrical tape from other work I had done.
Our procedure was rather simple. We marked our dock with 2 pieces of tape 20 feet apart. We then ran the chain back and forth between the marks. At each turn of the chain, we put some tape on. Not just a turn or two, but multiple wraps. For the rode, we unwound the rope strands enough to insert flags of tape.
Coloring on chain markings is another one of those areas where there are lots of opinions and approaches. Some folks have tried to standardize the approaches, and while they make sense, I went with a technique that is simple enough for our family.
Every different color on a given section represents 20 feet. For example, at 40 feet, you will find 2 different colors of tape. The colors don't matter in our system, just that there are different colors. At 60 feet, you will find 3 different colors, at 100 feet, 5 colors. We did the same approach with the rope. When all the chain is paid out, plus 2 colors of rode, we know we are at 140 feet of total ground tackle out (100 feet of chain plus 2 colors of tape on the rope).
Keep in mind, we don't have a windlass, so there are no binding issues.
In addition to the maintenance issue noted, if our chain ever has to be cut, then we would have to peel off some of the tape on the chain as well as keep the new length in mind as we spool it out if we get into the rope section.