A ch
ain stop is a metal guide that your chain runs through between the windlass and the bow roller or hawsepipe. It has a hinged finger. Lift the finger clear or remove it and the chain runs out freely. Drop it into place and the chain can’t be let out. You can still retrieve chain with the finger down, because the links push it out of the way as they pass.
They’re inexpensive, and a lot of boats don’t have one.
What it’s for
Your windlass is a lifting device. It isn’t built to hold the load of an anchored boat, and asking it to do that is how windlasses get damaged.
Once the anchor is set and your rode is all chain, put the chain in the stop. Do this even when you’re using a snubber. The snubber carries the working load. The stop is what’s there if the snubber lets go.
The case where it matters most is powering out a fouled anchor under engine. Hold the chain with the stop, not the windlass. Shock loads bend windlass spindles, and a clutch that slips or fails won’t hold the chain at all.
Holding the anchor home
The same reasoning applies once the anchor is back up on the roller. Something should be holding it firmly in place, and windlass tension shouldn’t be what’s doing it. Use the chain stop or another dedicated solution.
Devil’s claw
A devil’s claw does much the same job and is a reasonable alternative.
The difference is that it isn’t automatic. A chain stop with the finger down is a non-return mechanism, so chain comes in but can’t run out. A devil’s claw has to be fitted and removed deliberately every time.