Essential for safe anchoring is knowing how much chain you put out. If you guess, you will never sleep 100% soundly and I can practically guarantee you will at some stage drag. We use heavy gear, "five times the depth", dig it in well every single time and (touch wood) have never dragged. How do you know how much chain you have out? You either spend a fair bit of money to by an electronic chain counter or - before you leave port - you mark indicators of length on your anchor chain.
We use a very simple and effective way to mark our chain told to us by an old yachtie years ago but that few others seem to know about. The trick is to use polypropylene rope as you'll soon see - but, first, the counting scheme.
The first point at which we mark our chain is at at 15 metres from the anchor because we never put out less than that length of chain. We then mark the chain every 10 metres, using the colours of traffic lights so we can remember which colour is which. The tongue twister, "red lorry, yellow lorry, green lorry" also helps me. (Don't underestimate how easy it is to lose track when watching your chain race out. Something easy to understand and remember also helps guests and crew when they are helping you anchor.)
As an extra aid, we mark the first metre next to the anchor blue so that, when pulling it up, when we see the blue coming over the bow roller we know the anchor is just below the bow, without having to look over, and we can slow up the rate of winching.
This is how our chain is marked:
Next to the anchor 1m long Blue
First Mark = Red @ 15 metres
Second Mark = Yellow @25 metres
Third Mark = Green @ 35metres
Fourth Mark = Red @ 45 metres
Fifth Mark = Yellow @ 55 metres
Sixth Mark = Green @ 65 metres etc
Now here's the bit most others don't know about. Rather than paint the chain (or use different numbers of cable ties or knots on one link etc), which is messy to do, hard to see, wears off and has to be done in a marina, we use lengths of inexpensive, coloured polypropylene rope in the four colours above, each about 1 metre long and half to one centimetre thick (with the ends fused by heating). Each piece is "woven" into your chain at the correct distance from the anchor and ends up about 40cms long.The first time you do it, pull the chain out on deck (or marina) in measured intervals. "Weave" your cut lengths of rope through your chain at the appropriate intervals. The rope and chain passes easily over your windlass even if frayed.
As you drop your anchor chain and it whizzes out from the hawse pipe the 40cm coloured rope sections can be easily seen even with a torch on a dark night .
This rope is so tough it lasts for years - even when you are anchoring nearly every day. But it is cheap to buy and available just about everywhere. When the rope finally does become too dirty or frayed, simply replace it, on deck, as you pull in or put out your anchor chain (NB you will have to have your chain snibbed while doing it but once each piece is "woven" in just continue pulling in your chain as normal until you need to replace another chain marker). Each piece takes less than 5 minutes to" weave.".