TOM NEALE: Tables and formulas don’t give you a complete
answer. Different types of anchors will have different characteristics, and those characteristics vary with circumstances.
There are several things you should consider when you’re
choosing the right ground tackle.
To determine the right rig for my boat and the conditions,
I usually first consult the anchor manufacturer. The company
often has helpful information on its website, in its literature, or
via a customer-service agent. But in my many years of anchoring and living on the hook, I’ve always used the biggest anchor
ASK THE EXPERTS
BY TOM NEALE
ASK OUR EXPERT Our technical editor and DIY guru Tom Neale, creates this column from correspondence with our members.
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Anchor load capacity
An article on the BoatU.S. website titled “Anchoring” features a table with different
working loads for LOA/beam and activity ranges. I can’t figure out how to calculate
what the horizontal load-bearing capacity is for any one anchor-and-rode combination. Is there a formula that you can share? Meyer Lehman, Iowa
I could reasonably accommodate and
all-chain rode with a nylon snubbing
line. If you can’t use all-chain because
of boat characteristics, such as limited
weight load in the bow, use as much
chain as you can at the anchor end of
your nylon rode.
The bottom also makes a huge difference in choosing the best type and
size of anchor and amount and type
of scope. Performance varies among
different anchors in different types of
bottom. So I’ve carried three different
types of anchors on my larger boats:
a CQR, a Fortress, and a fisherman’s
anchor (Herreshoff). As examples, if
I’m anchoring in a sticky mud bottom
,I’ll probably use a CQR (or a Fortress).
If I’m anchoring in a hard-packed sand
bottom, I’ll probably use a Fortress. If
I’m anchoring on a rocky bottom (and I
try not to do this except in emergencies),
I’ll probably use a fisherman’s anchor.
None of these are hard-and-fast rules;
other things need to be considered. For
example, if the bottom has sharp rocks
or sharp trash, I’ll definitely use all-chain
to avoid having the nylon cut.
If I’m anchoring just for a few hours
in light weather, during which time I’m
watching whether I’m dragging, I may
use a little less than the 5-to- 1 scope
so often recommended. If I’m anchoring in or expecting severe weather, I’ll
probably deploy more rode than the
5-to- 1 scope, and I’ll be glad that I have
the heaviest anchor I can carry. I also
may consider deploying two or more
anchors, using one of several methods
of rigging these.
Further, what you do to set it is very
important. Just dropping it over and
doing the obligatory “backing down”
is often insufficient. Typically I’ll try