It
is a horrible feeling to wake up at 3:00 am after
spending the day on the water and finding a perfect
anchoring spot, only to realize that the winds have
picked up just a little bit and dragged your boat
against another nearby boat, or worse, into the middle
of a shipping lane, or onto rocks. Described here are
some of the common causes of this problem, and some
descriptions of how to avoid them. Equally annoying and
embarrassing is anchoring your boat while going to
supper or acquiring supplies and finding the boat gone
when you return. Your immediate thought is that it has
been stolen and so you call the police. If you are
lucky, the boat is found an hour or two later drifting,
the anchor still attached, but pulled up from it's
original location.
Wind
Dragged Boat or a Wind Direction Change
This
can occur even if you have the right anchor type and
size. All it takes is for the anchor to be set not quite
perfectly or for the bottom to be poor. Then, a bit of
wind will start dragging the anchor. Or, the wind will
change direction, causing the anchor to become
dislodged. You need to use two anchors set in a V shape
at the front of the boat. Then, even if one drags, the
other is still tight. If you expect a really bad storm,
use three anchors set like a V with an extra line
straight out front.
Tight
Anchorage
There
are degrees of tightness in anchoring. If you have room
for the boat to swing around without hitting anything,
then you can just use a two anchor V, where the angle
between the two anchors is fairly large (between 140 and
180 degrees, closer to 180 for less movement, but
requiring larger anchors). This keeps the bow in one
place, but allows the stern to swing around, keeping the
wind head on (this is usually more comfortable for
sleeping.) However, if there isn't room to turn the boat
around, either due to other boats, the shore or
underwater objects, then you need to set a V anchor set
at the front, and an additional anchor at the back. This
keeps the boat stationary, but tends to be less
comfortable. An alternative, if the wind is coming from
the stern, is to put the V anchors at the stern and a
single anchor at the front. Sometimes you can use trees
on land as one of the anchors.
Tide
Lifted Anchor
Fresh-water
boaters can be surprised by tides. If you set an anchor
at low tide, giving it a reasonable amount of rode, even
setting a second anchor, you can still be surprised to
find yourself adrift. What happens is that the boat
comes up on the tide (which can be as much as 14' or 4.5
m, but more typically around 3 ft or 1 m). This adds six
times that length to the amount of rode you need, so 18
ft or 6 m more rode. It doesn't actually lift the
anchor, just lets the angle decrease enough that the
anchor doesn't hold. The trick to setting an anchor in
tidal waters is to know how much extra rode high tide is
going to need, or just add an extra 20-30 ft.
Another
thing you should think about when anchoring at HIGH
tide, is whether you will have enough depth at low tide.
You don't (generally) want to ground yourself due to
anchoring in too shallow water.
Improper
Anchor Type or Size
When
you purchase an anchor, make sure you get the right type
for the bottom conditions where you go boating. Most
boating stores can help you decide on the type of
anchor, but don't be cheap, buy at least 1 good, heavy
anchor for each type of bottom you expect to have to
anchor on.
Fishing
If you
are fishing, you don't have to use these techniques
since you are constantly there watching, but you might
choose to in order to fix your position over a good
fishing spot. I'm not a fisherman, so I can't say as to
whether or not they would be useful.
(c)
Bill Wallace
1997 |
