The challenges of anchoring
Anastasia
Phil May and Andrea Twigg
Fri 20 Jan 2012 16:16
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There is a certain amount of skill required to
anchor a boat. First you have to pick a spot to drop the anchor. A
rule of thumb is you drop chain to around 5 times the depth of water. So
for 10 meters of water you would drop 50m of chain, ideally in a place where you
could draw a circle of about 35m radius (the chain hangs in a curve) around the
boat, and that circle would not contain any shoreline or other boats. You
usually don't have that much space and you have to have a couple of boats
inside your anchor circle. What you try and do then is arrange that if the
boats all generally point into the wind then they will not swing into each other
regardless of the wind direction.
Then you have to stick the anchor in the
ground. Often you can't see the bottom where you drop the anchor.
Reviews of anchorages generally talk about the "holding" which is a measure of
how well the ground will grab on to your anchor. There are different
anchors for different types of ground, but what you need for most cruising
anchors is fine, close packed sand. Too coarse (loose sand/gravel) and the
anchor will plough through it. Too fine (mud) and the anchor will
slide through it. If you are lucky then even if your anchor
slips it will just slide a bit and grab again.
It seems that some patches of ground in Portobello
harbour are mud. Last night we were unlucky because there was a clunk at
3am as Anastasia bumped into something. My first thought was a wind shift
causing us to swing into another boat, but running onto the deck it was obvious
that we had dragged back about 40 meters to hit another boat, and its
bow was now wedged between one of our hulls and the
tender.
To cut a long story short we separated the boats
and re-anchored well away from any other boats, with a lot of anchor
chain. In the morning I went over to see Bruno, the guy on the boat we
hit, and he was very nice about it. Apparently just a bit of anti-fouling
scraped off and not worth bothering about. We chatted in French for a
while (well he chatted and I tried to work out what he was saying). The
holding is really bad in that area and he has 70 meters of chain out for just 10
meters depth. Bruno is also sailing round the world, but his
batteries have failed and he has no working electrics at all. He has to
take the batteries in to Panama City for testing/replacement. He had three
massive batteries in his tender and we later saw him heading over to the dinghy
dock with them.
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