LETTERS TO THE EDITOR
I was at a boat show recently when
a plotter salesman was explaining the
virtues of these great photos. He
had an image taken of the Bahamas
where there was a dark S-shaped
band of water surrounded by lots of
light-colored water. “See how easy it
is to pick out the channel?” he said.
I knew that another image taken
maybe 10 minutes later, when the
sun wasn’t reflecting directly off the
sand under the shallow water, would
look completely different.
Another example: At Herrington
Harbor South Marina they moved the
entrance channel and jetties a few
years ago, and the NOAA chart has
never been updated. As a result, the
chart plotter displays your boat on
the jetty every time you enter or exit.
With a photograph of the entrance
taken recently, it would show the
channel in the correct location.
Now, if this photo was warped to
the chart, well, you can derive your
own scenarios.
It seems to me that people ought
to be made aware of what they are
looking at, along with its strengths
and shortfalls. I’ve thought about
writing something along this line, but
perhaps you could take a shot at it.
Nick Morgan
St. Peter’s, Nova Scotia
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FIRE EXTINGUISHING OPTIONS
I read an article recently in Fire
Engineering magazine about water
mist fire suppression systems. From
what I could determine, they could
be much simpler than chemical
gas systems for yacht engine room
applications, mostly because steam
expands so exponentially that
ventilation system shutdown probably
would not be required. They are also
safe for humans, reduce temperature
in the fire space for quicker post-fire
reentry, might even do double duty
in the galley, and definitely do no
damage to equipment, including
electronic equipment—for which
these systems were first designed.
A quick Google search for “water
mist suppression systems” delivered
a huge amount of data sources,
including the following simplistic
explanation, although nothing for
yachts was listed:
Water mist systems force water and
pressurized gas together to deliver a
spray of very small droplets. The
system suppresses fire in three ways:
1) As the water droplets contact the
fire, they convert to steam. This
process absorbs energy from the
surface of the burning material. 2) As
the water turns into steam, it expands
greatly. This removes heat and lowers
the temperature of the fire. 3) The
water and the steam act to prevent
