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When in estuaries etc with enough buoyage around, I follow the buoys. That
is considered as bad practice (never rely on a single means of navigation,
especially if it is floating) and one day, when fog comes rolling in, I
might be caught out. But on fine days with stable weather I trust the buoys
as long as they correspond to the chart.

When out at sea I maintain a DR position. I have the impression that across
the ocean people have different views as to what a DR position is: here, in
Europe, it is what the Americans call EP, inclusive of estimated effect of
current. The American DR is not something that we have a separate term for.
Please correct me if I've got it wrong.

I use as instruments: magnetic compass to steer and bear, Walker log,
plotting on paper charts with soft pencil making wide lines. I use one or
two triangles, marked along the edge in degrees, instead of a protractor.
The echosounder may on occasion also provide useful information.

I cross-check by taking one or more bearings, or a fix from a hand-held
GPS. I use the GPS waypoint function exactly like Arthur does: plot bearing
and distance to obvious points. That has the added benefit that no
corrections need be applied in case my voyage continues on a chart with a
different horizontal datum (waypoint and fix are affected in very nearly
the same measure by the datum change, so their relative positions stay the
same). The interval of fixes depends on the circumstances.

When beating to windward I see no use in protracting course lines on the
chart, and even on other courses the situation changes faster sometimes
than that I traverse the courses.

Currents in the North Sea are very much influenced by meteorological
conditions. Published predictions are avaraged data (related, of course, to
time of HW in a standard port) with no indication of its variation. At slow
vessel speed I think this variation has a detrimental effect on DR.

In practice I find myself somewhere between George's position and some kind
of formalised DR routine. No laptop; but I did programme a calculator to do
"a day's work" or any part thereof, which I seldom use.

My compass seems to suffer from exceptionally large (heeling) errors.
Before I restore my confidence in it, I hardly venture out to sea.

I do not correct my charts anymore because I get almost-new ones for free
on a pretty regular basis. But before a prolonged trip I would check up.
To the electronic corrections: I tried Stacy Hanna's way of inputting the
chart numbers but unfortunately the UKHO site takes only a single chart at
a time. People here running a Dutch website are looking into the chart
correction problem. No solution found yet.

Arthur, when you take speed from the GPS then you break the independence
between DR and GPS fixes. You can not be sure anymore that the one provides
an independent check of the other.

Steven

   

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