Why We Don’t Trust Moorings And Do Trust Anchors

by JOHN -  http://www.morganscloud.com/2007/04/01/moorings-vs-anchoring/

People are often surprised and even a little hurt when we turn down their kind offers to use their moorings in harbours we visit. They are even more perplexed as they watch us go to the trouble of anchoring outside the mooring field, often in a more exposed location.

Here is an example of why: Recently I have been trying to get a mooring put down in a sheltered inlet in Nova Scotia that will be heavy enough to withstand fall storms and even a hurricane. The first person we contacted, a reputable diver who does many of the moorings in that inlet, suggested a 2000lb (900kg) concrete block for our 26 ton boat. He said that was the heaviest weight he uses.

Now let’s think about that for a moment: Concrete loses half its weight in water and a block has virtually no form drag, so we are talking a total holding power of 1000lb (450kg). That is much less holding power than a good pattern 25lb (11kg) anchor provides. Would you trust your 56’ boat and home to a 25lb anchor, even in settled weather? I know we would not. Sure, when the block sinks into the mud the holding will go up, but not that much, and if the block moves at all from the snubbing of the boat, that benefit goes to zero.

I’m not trying to dump on the diver, particularly since, after a bit of discussion, he agreed that a lot more weight was required for our boat. But the point is—I know, you thought I would never get there—that many, maybe most, of the moorings in that inlet are at best 2000lb blocks.

Contrast that with our 120lb (55kg) SPADE that I would conservatively estimate can, when well set with plenty of scope, withstand a drag load of well over 8000lb (4500kg). That even makes a 1000lb (450kg) mushroom anchor (considered a heavy mooring weight on the east coast of the USA) look pretty wimpy. Even if it does move a bit, a good anchor, like a SPADE or Rocna, will reset itself, whereas a concrete block or mushroom anchor, once moved at all, will exert little more drag than its dead weight in water.

Finally, I know that our chain is in good condition and all the shackles are properly wired. Given all that, we know which ground tackle we will choose to give us a good night’s sleep.

Further to the above, when bad weather threatens we are always amazed how many cruisers pick up a mooring they know little or nothing about rather than heading for the security of a snug cove and their own anchors.