Tom Cunliffe has sailed tens of thousands
of miles all over the world and has been a
Yachtmaster Examiner since 197832 http://www.yachtingmonthly.com MARCH 2016
PHOTOS: TOM CUNLIFFE UNLESS OTHERWISE STATEDThe avenging
angels of admin
A few years back, I responded to a reader
who asked why, in today’s world of linked
functions, marine instrument makers
don’t use GPS ‘speed over ground’ and
‘course over ground’ to calculate True
Wind from the raw Apparent Wind at the
masthead transducer, rather than the
more primitive ‘speed through the water’
defi ned by onboard instruments. Good
question, you might think. Here’s the
current situation.
For most of us, True Wind has always
related to a fl agstaff ashore or a boat at
anchor. Apparent Wind at the masthead
is, in reality, the True Wind modifi edTrue and
Ground?
by course and speed
over the ground.
Unfortunately, until
recently, onboard
computers had no
access to linked GPS,
which meant that ‘True
Wind’ as given by the
dial was nothing of
the sort. In light winds
and a four-knot tide
the difference between
what a boat is doing
over the ground and
through the water is dramatic. Now that
GPS can be linked to Apparent Wind, you’d
think that the term ‘True Wind’ can at last
mean what it should. It doesn’t. Because the
electronics industry has been stuck with the
old imperfect system for so long, they feel
that to change their defi nitions would cause
confusion. Perhaps they are right. Anyway,Electronics can now
calculate True Wind
as we know it, but
the lexicon is rigid.
The Ground Wind of
change is blowinglike it or not,
True Wind by my
original defi nition
is now referred to
as ‘Ground Wind’
and ever more
it shall be. True
Wind on your instrument is Apparent
Wind modifi ed by speed log. My friends
at Raymarine tell me that the next
generation of readouts may well offer
Ground Wind as an option. That’s the one
we cruisers want. Racers may differ, but for
us, language changes and, like it or not,
so-called True Wind may soon be history.These three look innocuous enough trundling
by in the evening light, but look again.
There’s a blue light on the stern of their RIB.
They are the French customs, or perhaps the
Gendarmerie. Whoever they are, they have
draconian powers, so don’t be as casual as
I was once and forget your papers when
you set sail for foreign parts. If all is in order,
these guys can be so charming the ladies
might fancy jumping ship for the night. If
something’s missing, you don’t want to be
there. You’ll need:
Small Ships Registry (SSR, in date) or Part 1
registration, VAT-paid evidence, radio licence
(ship and personal), passports (including any
‘pet passports’ if required), certifi cates of
competence (useful but not mandatory along
the coast), insurance documents, an in-date
liferaft certifi cate if you have one, no out-of-
date fl ares and an up-to-date log book.
Last, especially in the Low Countries, hang
onto receipts for any red diesel and make sure
they’re stamped ‘Tax Paid’.These chaps are a fl oating nightmare if
you come up short on the paperworkDon’t get swept away by the tide
Are you on a collision
course? If it’s not
moving against its
background, you areOld hands learned this wrinkle at their mother’s knee, but if
you’re just starting it will keep you out of trouble. A boat is
rarely going where she’s pointing in our tide-swept waters.
When a buoy, or some other immovable object is making a
bow wave like this one, it is effectively another vessel under
way. The question is, are you going to hit it or not. It’s no good
noting that it’s a good thirty degrees out on the bow. In a
strong stream you might well be drifting forty or more degrees
from where you’re heading.
The only sure-fi re answer is to note carefully whether the
object is moving against its background. If it is, you’re OK.
If it’s not, alter course quickly and watch out. If in doubt,
go downtide of it, and never listen to folks with a scientifi c
education telling you this doesn’t work. It does, and it has
since St Paul’s ship went down off Malta.