Some clarifications.

"K. Smith" wrote in message
...

Not really, most ports have a compass swinging place set aside have a
look at the charts or ask. It usually has a set of posts you can tie to
& hold the boat on the various headings & "usually" they're sited so
there are at the very least a set of transits (2 or more landbased
objects that are on the chart & when in line mean your boat is pointing
to a known true heading as close to nth as reasonable given the
available transits)

You will have to keep the boat aligned and that's probably by keeping it on
the move along the line of sight. Tying it to posts that probably contain
steel reinforcements isn't a good idea. If you can keep it in a straight
line against a landmark, a GPS will work. Yes, you are correct about being
mindful of cross-track movements.


A GPS has no clue which way the bow of the boat is pointing & this is
what you're trying to determine. All a gps can do is tell you your
history track across the seabed & clearly you need to be moving for it
to even be able to tell you that.. You might be moving sideways,
backwards or whatever the GPS will not know so can't tell you.

The suggestion provided assumes a knowledge of GPS usage and remains a valid
suggestion.

I also note point 15 below??? DON'T ever do this, the compass must be
mounted so it's aligned with the boat's fore/aft centre line. It doesn't
need to be "on" or even near the centre line but must be completely
parallel with it.

The steps preceding 15 are used to determine the index error, that is how
much the compass is not aligned to the fore-aft axis of the boat. Hence it
is necessary adjustment by rotating the compass to bring it into alignment.

Tan PS