T&T: Anchor watch

[Milt Baker]

I guess I must be oversimplifying it, but using Nobteltec with the boat at
rest I just press the MOB key at the moment the anchor touches the bottom,
then start backing slowly as I pay out chain and set the anchor.  My distance
and heading to the MOB (the anchor) always shows, and unless I have dragged--a
rare occurrence with a 110 lb. Delta, all chain rode, and good nylon
snubber--Nobeltec virtually always shows me approximately the same number of
feet from the MOB as the number of feet of chain I have out, usually a little
less which accounts for the down angle of the chain.  Although the GPS
antennas feeding Nobeltec on my boat are about 20 feet from the bow, that
doesn't seem to matter because the GPS is reading the location where the
antenna is when I drop the anchor rather than where the anchor is and 20 feet
is not really enough to worry about, though I recognize it can be as much as
40 feet if the wind or current changes.  I also have tracking turned on, so
Nobeltec leaves a red track showing everywhere the boat has been since the MOB
button was pressed, a good check on things.  This system has worked for me
over many hundreds of anchorings aboard both this boat and my GB42 which I
owned for a dozen years.

If I want a backup, I also press the MOB key on my Furuno GP32 GPS with the
same results.  In a dicey anchoring situation where there may be problems, I
usually go with the Furuno for backup.  That happens maybe 5-10% of the time.

What am I missing?

--Milt Baker, Nordhavn 46 Bluewater, Fort Lauderdale



Jeffrey wrote:

This is one of my most favorite topics.  I've been working on various
anchor watch utilities for 6 years now.  The math is more involved
than you'd imagine.