David, is your opinion based on your experience of using a laptop in a
saltwater boating environment on a regular bases?  It seems a bit
optimistic to believe that an office type laptop that is used in the cabin
of a boat that stays in saltwater, will last  long enough to become useless
and obsolete.  On my boat, corrosion attacks everything electric.
Periodically I have a switch or fuse that fails from corrosion.  The salt in
the air seems to invade even equipment in well protected areas.  It seems to
me that the salt air would get to the computer long before it became useless
from obsolescence.

Glen

At 12:21 PM 1/14/99 -0500, Glen  wrote:

Arild  comments:

Glen has indeed hit on the core problem with computers aboard boats.
Although I work mainly in the Great Lakes, I have serviced boats operated
in salt water.
In addition, I worked for a government contractor who supplied equipment to
the Casot Guard.
As part of the production process, we had to  use special coatings to
protect the circuit baords  from high humidity and salt corrosion.
I recall once having to fix a boat which was only used in salt water for
about a month before  I had to replace half of the switches in the dash and
most of the light bulbs  due to salt water corrosion.

There are two approaches you can folow to ensure that your computer last  a
while.
Purchase a computer which is specially designed and prepared by the
manufacturer to withstand a wet and corrosive environment or control the
environment  to minimize the effects.

Desk top computers are inherently more prone to corrosion damage than most
laptops. due to their design. The reason is  the number of  removable
connector points.
Laptops have most functions built in to the main board with special chip
sets that are soldered in place.
Desk top computers have many  more slots  for configurable and user
selected option boards. Modems, display  driver, sound cards and even  hard
and floppy driver controller boards  are often plugged into the mother board.
Desk top computes have fans which draw air through  the cabinet. If that
air is moist and salty , corrosion will be accelerated.
Laptop have spill proof keyboards and uses a differnt cooling system.
Desk top computers use high voltage  CRT displays as a rule. The high
voltage  supply is more prone  to leakage currents due to a conductive
film from salt air  than the LCD screens used  in laptops.

So what can you do to minimize  salt air corrosion.
If you have  a desk top unit  keep several dessicant packages insde the
cabinet. These absorb moisture from the air. They are reusable by heating
in an oven ( not a microvave )
Most computer equipment shipped overseas comes  with small satchels of
dessicant inside each box.
Ask your local computer store  to give you the little bags which are often
just tossd into the garbage when they open  boxes and assemble  a system
for a customer.
Perhaps the worst thing to do with computer equipment is to have it
alternate  between heating and cooling  cycles.  Moist air will condense on
colder surfaces.  A warm surface will not collect condensation.  Perhaps
Joe Engle can  expand on the specifics of  PNW atmospheric conditions which
difer markedly from the humid Florida weather.

If you  only use a computer occasionally, store it  in a dry place together
with more dessicant bags when not in use.    Comments have been made on
this list about the amount of moistuer put into th air with propane
heaters. This is also a factor to consider  if you use consumer electronics
onboard.

There are conformal coatings available, even from Radio Schack; but unless
you are pretty handy  with working on electronics I DO NOT RECOMMEND  that
you try using them to protect baords yourself.
The coating migrate into the tiniest cracks and unless you really know what
you are doing; you are likely to create more problems than you solve.
That is advice coming from a QA Manager who has dealt with just such
problems on the production line.

Laptops are definitely a better choice  onboard than desk tops.  Mrinized
laptops are an even  better choice;  however they do cost considerably more.

Finally,  larger boats with air conditioning and central heating , perhaps
with a dehumidifiers added are the best seagoing environments.  Open
cockpits or non  conditioned environments are the worst places for computers.

Cheers

Arild