Compass?
So I'm doing the electronics on my boat, 63 ft steel shrimp boat conversion, and I'm looking at compasses.
Some books stress how important they are and say to get the best you can afford, but the redundancy of
electronic compasses and GPS systems how often do you really rely on a free-standing compass?
What do you guys use and recommend?
Also, how detailed are your paper charts And how often do you pull them out?
Sorry about these dumb questions, but I'm a few days from pushing off and know nothing.
A good magnetic compass is a must. Hand steering down the West Coast of Baja
California at night after the autopilot failed, the magnetic compass was
used constantly.
Regarding paper charts: I use them at all times, as a backup and for
plotting positions, especially in unfamiliar waters.
Dean Crothers
M/V Emily B
DeFever 50, LRC
Currently moored in San Carlos, SON, Mexico
-----Original Message-----
...I'm looking at compasses.
...Also, how detailed are your paper charts And how often do you pull them
...out?
----- Original Message -----
From: "Lorenzo Boelitz"
I'm looking at compasses.
Some books stress how important they are and say to get the best you can
afford, but the redundancy of
electronic compasses and GPS systems how often do you really rely on a
free-standing compass?
REPLY
That would depend on what you would do if your electrical power totally
failed but your non electronic diesel kept running.
How would you keep the boat going in a straight line towards your
destination?
If the answer is pull over to the side and Call US Tow Boat, then you don't
have to bother.
If the answer is an honest admission that such a failure would leave you
adrift and not sure of direction, get a good one.
By Good one I mean a decent four inch or larger compass card and a
compass binnacle equipped with Kelvin spheres for compensation for the
vessel steel. Lastly, get it corrected ot do it yourself whiel the
electronic stuf is still working.
Gemini was a popular make and could be had in both plastic boat version
and steel hull. The difference being the mounting brackets for the soft
iron spheres. BTW these brackets are bronze - thus non magnetic.
Also, how detailed are your paper charts And how often do you pull them
out?
Sorry about these dumb questions, but I'm a few days from pushing off and
know nothing.
REPLY
Not dumb - at least it shows you are aware of shortcomings in your
knowledge base.
Paper charts should cover all the waters you intend to cruise in a given
region and include harbor details of likely bolt holes you might divert to
in case of equipment problems or bad weather.
If your plans are for wide ranging cruises, you only need to get one
region at a time. Quite often you will meet cruisers going the opposite
way. It was customary in the past to swap paper charts.
Arild
----- Original Message -----
From: "Lorenzo Boelitz"
Some books stress how important they are and say to get the best you can
afford, but the redundancy of electronic compasses and GPS systems how often
do you really rely on a free-standing compass?
REPLY
Your question opens up a whole slew of questions including the
philosophical question of should we cling to older technology.
Many people are so accustomed to seeing electronics used in mission
critical applications like air planes, space ships, and other
transportation applications they naturally assume the stuff they get a West
Marine or Sam's Club for $49.95 is just as good.
They do not realize that the majority of recreational boats are built for
the lowest possible dollar and almost none of them are subjected to surveys
or inspection during constructions. Marketing claims notwithstanding.
Commercial and military vehicles of all kinds are subjected to many more
design reviews, exhaustive reliability studies and in many cases are built
to be triply redundant. Then when they are built they are subjected to
extensive factory acceptance tests that quite often simulate all sort of
failures to test that the back-ups and redundant equipment actually
performs as intended.
When did you last see this done on a recreational boat? They splash the
hull and if it doesn't leak, it passes. System check-outs consist of
flipping the switch and if the thing shows signs of life, its a pass.
Ever see anyone do a deliberate over-current protection test? If your
battery suddenly overheats then short circuits, will the installed
equipment actually protect the rest of the system and the fire supression
equipment actually put out the fire?
Such tests take a lot of time and are expensive when consumables are
involved. No one wants to pay for it. So it never gets done unless a
contractural clause insist.
Where then is the inherent reliability? Redundancy? beut what if the
single source of power fails. Then what?
Lloyds of London standards require all critical systems to have two
completely independent power feeds including battery banks and generators.
If you haven't got that you do not have true redundancy. I have seen glass
bridges rendered totall dark because one $50 breaker failed. It was the
main feed to the breaker panel. A bad crimp could do the same. One loose
bolt caused a fuse holder to overheat and the connection failed in the
middle of the bow thruster being used in across wind.
You do not always have the luxury of time in which to rig alternatives on
a dark night or under stressful conditions.
Magnetic compasses are still specified as primary emergency equipment
because it is the only sure fire way to determine heading and direction of
movement in the total absence of power. And if you install it might as
well make suer it reads correctly. Get a compass adjustor. In Canada it is
actually the law boats over 24 feet must have a compass and an compensation
card. In the past they were somewhat lax about enforcing it, but since
Transport Canada took charge, this clause has been highlighted in the Boater
manual.
Arild