Knowing the type of bottom into which you are setting the anchor is the basis of all decisions from basic security, to the correct scope, and the best anchor to use.

We have recently anchored in three very different set of conditions, so we thought a few comments might be of interest.

On the assumption that you do not know from pilot or guide books the bottom type, the first clue is sound.

If the bottom is rocky, or coral, the chain is going to make a grating sound that is distinct. When the bottom is hard and uneven, the acoustic signature will change abruptly as obstructions are met and overcome.

The motion of the boat as you back down to set the anchor will be jerky as the chain grabs and releases. The anchor may slip back until it hooks a rock or coral head, and then there will be a jerk.

With mud and sand the situation is very different. The chain is quiet, and motion is smoother. Backing down you may notice a soft deceleration as the anchor digs into to the mud. That was the case a few days ago when we had a really firm bite (as shown by the mud left on the anchor).

Last night, anchoring in a new spot, there was never that firm deceleration of hard mud. Initially the anchor just kept slowly slipping, very unusual for our big Rocna, even at our normal three to one scope. We brought the anchor up to check for weed and it was clean. So we repositioned and anchored a second time using five to one scope. This did the trick.

As we have discussed before, a fish finder-style depth sounder will also give hints to bottom condition. Hard bottoms return multiple echoes, while soft bottoms typically have a single trace.

Back to that muddy anchor. Although we have a pump forward for salt water wash down we rarely use it. A dirty anchor like this is dipped and returned to the bow roller a couple of times to clean it. If there is space, and we remember to do it, backing up with the anchor just below the surface also does a good cleaning job. We don’t worry about the chain as the self bailing anchor chain well self cleans the chain once we are under way.