When an anchored boat spins, the anchor chain twists, and the anchor can come up backward. One solution is an anchor swivel, but failures with some poor designs are a concern-a lovely stainless swivel on one of our test boats had an interior crack that became visible only when disassembled. And as we found in our most recent test, many swivels arent very effective at reducing twist due to the inherent friction in the swivel.(see How Well Do Swivels Reduce Twist, Practical Sailor March 2016 online).
You can reduce twist by making sure your chain does not have any twist in it, and, once you have done this, you simply maintain the same alignment with the gypsy when deploying or retrieving your anchor. When your anchor is deployed and you are re-connecting the anchor chain to your windlass gypsy, there are four possible ways to orient it in the gypsy. There is also a 50-50 chance that your anchor lifts snugly into the anchor roller without adjusting the length.
Once you have the chain aligned as it should be, it should not rotate in the gypsy. The chain is straight, and the anchor will spin slowly on the way up and fit snugly on the roller onto the roller. But how ow do you know it is straight, and how do you maintain the same alignment?
One thing that has worked for me is to mark the up side of the chain at regular intervals with paint. By making sure that the up side of the chain inboard of the gypsy (on the locker side), is aligned with the next up side of the links on the other side of the gypsy, I know that the chain will come up straight and any twist in the chain will untwist as the anchor comes up.
The main problem, as I see it, is that many boaters have twisted chain in their locker, often without even realizing it. In many cases, they had replaced the windlass with the chain still in the locker. In the process of re-feeding the chain, they had introduced a twist that was not there with the old windlass.
The solution? Pull of the chain out into a box on the deck and then re-feed through the new windlass from the topside. Be sure to attach the bitter end to a padeye or u-bolt in the locker with line or lashing that can be quickly cut if you need to get underway in an emergency. By re-feeding the chain into the locker, it should now be aligned without any twist. Since the chain cannot spin in the gypsy, it should stay that way.