How soft is "soft" mud when anchoring?

[a64pilot]

To expand on what Zee said, an issue with mud is sometimes what's in it, you think you got a great anchor set, then when you go to leave find out it was because you hooked an old sunken tree or something, have a trip line set if you can, cause I think I heard something about Croc's and it may not have been about the shoes?

[Fortress]

Troppo, the OP, referenced and provided a link to a very thorough and well-written article about the Chesapeake Bay soft mud testing. Much was learned about anchor performance in soft mud by many who were aboard, which included boating writers from magazines that had a combined circulation of over 1 million readers.

Here are some images of the mud that was pulled up from this testing:

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Before power-washing:

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After power-washing, with clamshells still attached:

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[troppo]

I previously asked in this thread about sonar/fish finders and their usefulness or otherwise for checking the bed consistency. Here's a snap of my fishfinder, can anyone tell me what it is saying about the bottom?

[Emmalina]

Originally Posted by troppo

I previously asked in this thread about sonar/fish finders and their usefulness or otherwise for checking the bed consistency. Here's a snap of my fishfinder, can anyone tell me what it is saying about the bottom?

Thicker the line softer the mud ! Fishfinders are also very good at displaying a rocky bottom ! Only use mine for this now as the wife calls it a fish liar !

[troppo]

Originally Posted by Emmalina

Thicker the line softer the mud ! Fishfinders are also very good at displaying a rocky bottom ! Only use mine for this now as the wife calls it a fish liar !

Is the line in the picture thick or thin?

The thicker the line the softer the mud: what that is telling me is I need to compare scans of various locations in order to understand this particular scan. I would not know if the line was "thicker" or not unless I had something to compare it with. I guess it would be especially helpful if I found a spot where I knew the mud was extra soft and took a photo of the scan just to give me a baseline to compare with.

So I am guessing that this specific photo by itself does not give much indication of the bottom apart from it not being rock.

Louis

[StuM]

Yep, you need to establish your own baseline of how many meters your particular finder penetrates at 50 and 200kHz for different sea beds.

[rognvald]

I find it amazing that it took until the 16th post, Cheech, to refer to the bottom characteristics printed on nautical charts. Is this a result of most mariners using electronic navigation vs. traditional paper charts? We always refer to paper charts for a reference to the nature of the seabed for a prospective anchorage. Our experience in mud bottoms is to use the heaviest anchor available that will sink below the surface as it settles rather than laying in the mud with zero holding power. The worst we ever dragged in high winds(50 knots) was in Factory Bay, Marco Island, Florida. We had a Fortress FX23 and a Danforth 22H set off the bow that dragged once over 20 knots. After the blow, we set our CQR imitation, 32 lbs, and it held through several 40-50 knot blasts. Good luck and safe sailing.

[troppo]

Hi Rognvald, I think paper charts are useful, I use them but I admit, more for support for my digital charts. However, my paper charts have negligible bottom information.

I am digressing here, but not only is there a lack of bottom info, the depths can not be trusted. Just checking my main anchoring spots, both the paper and digital are wrong. Both show, for example, that for my usual anchorage at the mouth of the Fitzroy River I am anchoring on banks that emerge to 1.5 metres high. Not true. The depth is more like 4 metres. The paper chart does warn that the area has shifting shoals and those without local knowledge should not enter the area without a pilot.

I guess no matter what information we have access to, it doesn't take away our responsibility to be careful.

[rognvald]

Originally Posted by troppo

Hi Rognvald, I think paper charts are useful, I use them but I admit, more for support for my digital charts. However, my paper charts have negligible bottom information.

I am digressing here, but not only is there a lack of bottom info, the depths can not be trusted. Just checking my main anchoring spots, both the paper and digital are wrong. Both show, for example, that for my usual anchorage at the mouth of the Fitzroy River I am anchoring on banks that emerge to 1.5 metres high. Not true. The depth is more like 4 metres. The paper chart does warn that the area has shifting shoals and those without local knowledge should not enter the area without a pilot.

I guess no matter what information we have access to, it doesn't take away our responsibility to be careful.

Hi, T,
I probably assumed, incorrectly, that your charts(British Admiralty Charts?) contained the same information our NOAA charts. Our "large scale" charts show excellent detail including depths, bottom characteristics, dangers, etc. We always rely on our paper charts as a first reference when choosing an anchorage and they are, in my opinion, very accurate. However, a prudent mariner always uses his sea sense when appraising a new potential anchorage and proceeds cautiously. We have been fooled several times when the bottom characteristics seemed good but tidal sluicing, uncharted weeds and isolated bedrock/coral patches did make the anchorage untenable. So, trust and confirm. Good luck and safe sailing. P.S. We anchored Saturday night in an area that was charted as mud and when I pulled the hook the next morning, it was, indeed, mud but discovered a veritable salad bar on the end of my CQR. Rognvald

[ranger58sb]

Originally Posted by rognvald

I find it amazing that it took until the 16th post, Cheech, to refer to the bottom characteristics printed on nautical charts. Is this a result of most mariners using electronic navigation vs. traditional paper charts?

Perhaps a decent reason to use digital raster charts in place of or in addition to digital vector charts. The raster charts on our plotter show the same info as the original NOAA paper charts, including bottom characteristics.

-Chris