The CQR, a favorite anchor among cruisers, along with the more modern version, the Delta, are anchors based on a farm plow. The idea is simple, plows dig into the substrate and digging deep into the substrate is a desirable feature of a good anchor. The problem with plow anchors is that they are plows.
Plows are designed to dig deep into the earth and pull through it, turning the soil to prepare the land for planting. Plow anchors do the same (except not for the subsequent planting).
An anchor dragging is characterized by the anchor not holding onto the bottom and sliding across its surface. Plow anchors don’t necessarily “drag” when they are set well, but instead “plow” the sea floor. This is what a plow was designed to do!
The problem comes in when someone anchors with a plow anchor in an anchorage. Other yachts are anchored with good anchors that hold in place while the plow anchor slowly plows the sea floor. This means that the yacht anchored with the plow anchor will slowly meander through the anchorage and potentially into other yachts!
While snorkeling in Formentera, I noticed a 30 foot sailboat that was anchored in shallow sand with a CQR. I was looking for treasures in a small patch of seaweed near the sailboat and noticed that in a 20 minute period, the sailboat had moved significantly! So did the CQR anchor.
There was minimal wind and the anchor was not under any load. The chain fell from the yacht vertically to the bottom and then turned a 90* angle to make its run to the plow anchor. Under no load, the anchor was making a huge plow mark on the sandy bottom!
After seeing this, I began noticing many long plow marks on the sandy bottom. Some were hundreds of feet long! On the clear morning before any wind had picked up, you could clearly see the sandy bottom and the cross cross of plow marks left in the sand.
Plow anchors were a popular anchor when they first came out and created quite a following behind them, but their favored use was due to personal opinions and the lack of actually good anchors to choose from. Now there are modern anchors that really do hold well and keep your yacht stationary in the water.
These roll bar anchors will stay put, even as the wind changes direction or the tide reverses. They will stay where they are and keep you safely anchored to the bottom!
Please, for the sake of everyone around you, please stop using plow anchors.