on a boat.
||Please send any comments to me.
This page updated: August 2014
Marilee Shaffer's rules of using a computer on board:
- No splashes/spills on it.
- Run it fairly often.
- Strap it down.
- Have a good, clean power source.
From JM Cook on Cruising World
Getting a 'marinized' computer is completely unnecessary.
... other than tossing it in the ocean or pouring salt water
directly over it, NO protection is needed. ...
From Bob Taylor on the
WorldCruising mailing list
... I will not purchase a "ruggedized" unit. I have talked to a number of friends
who have years of experience with the standard laptop models and their comment was: They
will become outdated and be replaced with a newer unit before they will die. This assumes
you take proper care of them which I will. In my case I will buy one of the Pelican
waterproof carry cases since I will be carrying the unit in the dinghy often. ...
From Brad Geres on the
WorldCruising mailing list
... We store our 'puter (while still warm from use)
in [a Pelican case] we've
modified by replacing the pluck-foam with pads made by
loosely stuffing vermiculite in old nylon stockings.
The vermiculite draws any remaining moisture out of
the case. Incidentally, we store our old Plath
sextant and the stopwatch in an identical case. ...
My first experience:
My first laptop was 3 years old when I bought it, and started dying after
another 2.5 years aboard. Other than old-age-related problems (the
laptop's old age, not mine), the only boat-related problem was
corrosion on the connector from the internal CMOS battery to the
motherboard. Unfortunately, this was just about impossible to fix,
since it's a tiny, surface-mounted connector, and the corrosion
was on both parts.
This may have been aggravated by the way I was using the computer:
I removed the main laptop battery (it was dying anyway), connected the laptop to
boat's batteries, and only turned on the power when I wanted to
use the laptop. I think this let the CMOS battery run down
a bit, and that probably accelerated the corrosion.
My second experience:
My second laptop was new. The keyboard started dying after
2 years aboard. The DC-to-DC power converter tended to melt it's cigarette-plug
connector when charging heavily for more than 15 minutes or so.
Things you want in a marinized computer
The replacement keyboard died about 2.5 years later.
- Drive bays, port covers, keyboards and track pads securely sealed and gasketed.
- Hard drives gel-packed to protect from vibration and impact.
- Strong hinge on laptop.
- Specially coated circuit boards inside.
Several people say: Panasonic Toughbook is good.
Some say: Ocean PC is bad.
From Adam Chorley:
I'm an electronics technician, and have noticed
people bringing me their VHF radios with WD-40 inside the case - obviously
trying to stem the corrosion issue. This is a big no-no. What I have done
with all my electronics (including those I service for marine use) is
apply a coating of MILSPEC "conformal coating" to the PC board (both
sides) after using silicon [silicone ?] to glue all parts that are susceptible
to movement/vibration. I did this with a portable VHF radio
(non-weatherproof) I have had on 3 different boats for over
eight years - it is still as good as new. You can source
this stuff from any electronics store, but I would recommend
application only by qualified people.
STO.P's "Computer Hardware in the Marine Environment"
Laptop versus desktop:
From JM Cook on Cruising World
If you can avoid a laptop in favor of a desktop, do it ...
Laptops are difficult to repair ...
A desktop, on the other hand, and especially a clone,
will be easily repairable and upgradeable for the next 5 years
plus you'll be able to find pieces from here to Bangkok.
But from Russell on Cruising World
Laptops consume less of two things that are in short supply on
many boats: space and power. They have a third advantage. Laptops are
designed, more than desktops, to work under motion,
and even to take hard knocks. The disks are cushioned, the connections more
secure, etc. ... [And they're portable, to shore.]
From Bob Taylor on the
WorldCruising mailing list
... The desktop I use I built. It is generic parts so I have a
chance of finding parts when in out of the way
places. One of the problems sited with laptops is their
parts are special and sometimes hard to find. ...
From Douglas Sterrett on the
WorldCruising mailing list
... The main reasons I am going to install a desktop system
are increased hard drive capacity, expandability, and upgradability. With
a laptop you are pretty much stuck with what comes with the machine. ...
From Glenn Duncan on Cruising World
... a modern TV and VCR will require only about 120-150 watts AC;
less than a desktop computer, which will typically need around 275-300 watts.
(One caveat: charging the capacitors in the monitor on startup takes the most grunt.
Turn it on first; 20 seconds later turn on the CPU.)
The laptop I use at work runs hot.
That can't be a good sign of long-term reliability.
From letter from Luc Callebaut and Jackie Lee in 6/2000 issue of
Seven Seas Cruising Association
Factors to compare
1) laptops, new or old, do not last in the salt air environment!
2) every time it needs to be fixed you will hear: "we
need the parts, we have to order them at high cost and it will
take a long time" or "it's an older model, I don't
know if we can find the parts any more and laptops don't
take standard parts!" ...
[so they bought 3 cheap, used, identical 486 laptops
and vacuum-sealed 2 of them to use for spare parts]
Laptops are good
- Take less space.
- Consume less power.
- Less weight.
- Portable (can use it anywhere on boat, use it off the boat).
- Can prevent theft by taking it off the boat, or hiding/locking it in boat.
- Slightly more rugged (expected to take a few knocks),
unless lots of external devices are hanging off it.
- More compatible with 12V battery power.
Laptops are bad
- 50 to 100% more expensive.
- Easier to steal.
- Harder to repair (but using USB peripherals helps a bit).
- Harder to upgrade (but using USB peripherals helps a lot).
- Harder to shield the RFI they produce (especially if case is plastic).
- Water damage to keyboard/screen can require replacing whole machine,
or at least sending whole machine back to manufacturer for repair.
- Harder to use: smaller keyboard and screen, and worse mouse.
- Probably run hotter than a desktop, which is bad in an already-hot boat.
I often point a 12V fan at the back of my laptop when using it; I think that helps.
Display of my Dell Inspiron 1100 laptop generates RFI that I can hear
in the shortwave radio. During booting, I can hear the RFI go away when
the display is blanked and come back when the display is lit again.
RFI goes away if laptop is unplugged from power converter that connects it to house batteries.
Can't directly connect a [desktop] computer to the 12V DC power in the boat.
The 12V DC is not clean enough, and the computer uses other
voltages such as +/-5V DC and -12V DC.
directly connect a laptop. Might want to condition the power;
see STO-P's "Using DC Power Fault Protectors"
or just search the Web for "laptop power adapter" and look at ones for automobiles.
Could get surges, especially when starting engine.
From Todd Dunn on Cruising World
Your computer runs on both 12 and 5 VDC.
You can convert any computer to a 12 volt source by ripping out
the AC power supply (really just a multi-tap transformer
with a couple of voltage regulators) and replacing it
with a couple of DC to DC converters - one 12 volt to 5 volt
and one 12 volt to 12 volt. I suggest using two converters
because DC to DC converters have very stable voltage outputs - i.e.,
the 12 volt output of a 12 volt to 12 volt converter will stay
at 12 volts independent of the inpout voltage as long as the input
voltage stays within the converter's specs. A couple of good,
reasonably high output converters will set you back a couple
of hundred dollars, but they will solve your power problems.
They are also small enough that you can simply put them inside
the computer box where the AC power supply was.
Check out MajorPower.Com's DC/DC Converters
or go to any good
electronics/electrical equipment supply house.
From Anthony Powell on WorldCruising mailing list
I asked the list a year or so ago about powering a 24v laptop with 12v.
The answer was to just wire it up to the 12V. It seems that all the CPU
needs is 3v and the rest is for the charging of the laptop battery.
From Jim Donohue on rec.boats.electronics newsgroup
1. Does the laptop have an adapter for 12 volt usage?
The answer is of course yes. If the company does not make one there is one
available. I know of no low-power device that cannot run on 12 volts with
2. Will the laptop run off 12 volts without an adapter?
For many of the laptops the answer is yes. My somewhat elderly Acer runs
fine off 12 volts. I suspect that many laptops will, in fact, run off 12
volts - even if their manufacturer does not agree.
3 Will my laptop run off 12 volts and charge its batteries without an
Now the answer is likely no. Most of the laptops require some higher
voltage and control circuitry to both operate the laptop and charge the
battery. You may well be able to run the laptop but the battery is not
charged at all or only partially charged.
From Glenn Duncan on Cruising World
... you may find your laptop will work directly off the 12 VDC onboard.
We've been running two laptops (an IBM Thinkpad and a older Compaq) directly
off 12V for almost two years with no problems.
The important thing is the voltage of the laptop's battery, NOT the output of
the AC adapter. My IBM, for example, uses an 18V adapter, but the battery is 9.6V.
The differential is needed to charge the battery but not to run the laptop.
I remove the battery and run directly from 12V.
Because I worried about voltage spikes during engine start (as the alernator comes on line)
I avoid starting up when either laptop is connected. I also put MOVs (those "Protect Your
Engine Computer During Jump Starts" gadgets from auto accessories shops) across the
power leads for each computer.
As it happens, I've screwed up a few times and started up while the Compaq was
working without any problem. MOV or blind luck or over-caution? Who knows?
Voltage converter to run a laptop from the 12V battery, rather than the inverter:
Generally called DC/DC converters or adapters, or auto laptop power adapters, on the web.
"Step-down" converters go from 12V to lower DC voltages, and are fairly cheap ($25 at
"Step-up" converters go from 12V to higher DC voltages,
and are more expensive ($50 to $100 or more).
A third option is a small inverter that plugs into a 12V socket and produces AC.
N4UAU Voltage Booster ($68 fully assembled, but web site is gone)
"Auto / Airline Adapters" from Lind Electronics
(800-524-6464; maybe part 40-212 $50)
Caution: charging my laptop's battery pushed my DC-DC converter so hard that it's
cigarette-lighter plug melted
! This is a plug that came as part of the
DC-DC converter; obviously it wasn't rated for as much current as the converter
From Mark Melvin on the
WorldCruising mailing list
PC's have a special power supply that takes in AC current and puts
out very carefully managed +/-12VDC, +/-5 VDC, and +3.3VDC on newer
"ATX" style motherboards (which are almost all of them made in the
past 3-4 years except for homebuilts. Older motherboards are "AT"
style). Fluctuations in the output voltages are fatal to CPUs and
hard drives, so building your own is _NOT_ a good idea, to do all the
proper rectification the parts would cost you more than an assembled unit.
Most DC laptop adapters (car adapters) that run a laptop from the
cigarette lighter of a car take in 12VDC, turn it into 120VAC to feed
the laptop's built in AC->DC power supply. Horribly inefficient but
most people don't realize that. Some DC laptop adapters do bypass the
DC->AC and feed their DC to the the rectification side of the
laptop's internal supply, but those are rare and not as stable; the
laptops used with them tend to end up with lower battery life if used
long term because the rectification circuit is starting with a lower
DC voltage than the AC->DC supply would have generated.
The regular PC (not laptop) AC->DC power supply modules are easy and
cheap ($20) to replace with new AC->DC power supplies, but what
you're talking about is a DC->DC power supply.
Many companies make these, but you're not going to find them in
CompUSA or Radio Shack, you need an industrial supplier (e.g.
From Rufus Laggren on The Live-Aboard List
PC Power & Cooling
came out recently with a supply for standard PC's that runs entirely off
12 volts. I believe it's 250 watts max.
It used to be the case that the refrigerator/freezer was by far
the biggest power-hog
on DC-based boats. But running a computer can take more power than running the refrigerator !
And recharging a low-battery laptop will take even more
And the refrigerator typically runs about a 50% duty-cycle; the computer generally runs at 100%
while you're using it.
Conversion efficiency of those small "wall wart" or "brick" AC adapters can be as low as 1/3;
they can waste 2/3 of the power. And they consume some power even when no device
is plugged into the DC side. Add the losses in your DC-AC inverter, and the
"battery DC to inverter to AC to brick to DC to device" chain can be very inefficient.
Peripherals (printer, scanner, etc):
Useful to have scanner and printer (instead of a photocopier),
to make copies of crew lists, passports, etc.
Many peripherals can be powered from the USB cable, instead of a separate
power supply. USB-powered floppy drives, CD drives, scanners, Wi-Fi adapters are available.
But few printers ! Some peripherals draw too much current from the USB port:
my USB DVD drive causes "USB device has tried to draw too much current" errors on
my old Dell laptop.
USB supplies 5 VDC, from 100 MA to 500 MA per port.
Some battery-powered mobile printers are available. But it's very
hard to find out what DC voltage popular printers require; the printer companies
just don't think in those terms. HP inkjets seem to require both 20 and 36 volts DC.
Most Lexmark printers require 30 volts DC.
From JeffeeB on Cruising World
In general you need at least 1000 W of available capacity to run a laser printer.
Idling a (modern) laser printer draws very little, in fact many of
them will automatically "sleep". When actually
printing, a laser printer takes a
good amount of juice. But most importantly, there is a very big surge
when the first page in a print job arrives: all the motors spin up, the
laser comes on, and it begins to heat up the fuser roller to several
hundred degrees, before the first sheet of paper gets to that roller.
From Mark Mech on The Live-Aboard List
[Re: printer that will run on a battery pack and is made
especially for use with a laptop:]
I thoroughly checked out portable printers for the boat, but ended up
getting a standard HP color printer due to operating costs. The new HP's
have a paper tray that folds and you can refill the cartridges for about $5.
The micro Canon has very small, very expensive cartridges and also needs
new print heads every few cartridges. The operating costs are very high; you
could buy a $45 inverter to run the standard printer and it is about the
size of a large toaster when folded. The power supply is 18v @ 1 amp so that's
only 18 watts; the smallest inverter would run it.
From Rob Hepler on The Live-Aboard List
If footprint isn't a concern, 'regular' office-type
inkjets are dead cheap. Some months ago I bought a
refurbished Lexmark for $40 with a $20 rebate. That makes
it cheaper to buy new printers than new cartridges. All
Lexmark printers I have looked at do *excellent* text. At
that price, a $40 inverter to power it is still a bargain.
Especially if it powers the blender, too :-) I also got a
free Lexmark (different model) with a computer bought from
Dell. Haven't even taken it out of the box yet; it's the
backup for the $20 model.
Use household/commercial/industrial stuff
rather than marine $tuff; it will last longer than you
think (especially in my dry trimaran) and is LOTS cheaper.
From Chuck and Linda 7/2009:
"I like the Canon IP-90 which we have been using for the past 6 years.
Small and always works great."
"Epson and newly HP have 'waterproof' ink; I switched for Epson and the ink is much better."
From Susan on the IRBS live-aboard mailing list:
Re: Is it practical to use charting software on one's laptop while cruising ?
We tried a system and found it completely impractical for our boat.
There wasn't any good place to put the laptop in the cockpit
and we couldn't see the screen due to sun, glare or position of the helmsperson.
We put the 'puter down below and wore ourselves out running up and down to
check our position. It wasn't long before we realized we were checking our
paper charts, completely ignoring the computer running in the cabin.
Computers and water don't mix well: pic.
Summarized from Captn. Jack's "CRT monitors on board":
- Palm Pilot is "splash-averse"; get a neoprene case.
- If your laptop has a built-in modem, use a "modem saver" when connecting
laptop to phone system. That way, bad wiring/voltage/current in phone system doesn't
kill modem circuitry on laptop's motherboard.
- Scan paper documents in and store them electronically on CD-ROMs.
- The little mouse-nub-thing on my laptop got sticky and eventually dissolved, probably
from solvent or diesel on my fingers after doing boat jobs.
Even washing hands may leave some residue.
- Many people warn about computers overheating on boats.
Most mainstream computer use is in air-conditioned environments,
not the more stressful situation of a hot boat.
- Lithium-ion batteries, used in cell-phones and other devices,
can explode or burn if exposed to serious overheating.
CRT's generate significant magnetic fields that can affect compasses and other instruments; LCD's don't.
Summarized from Captn. Jack's "Screen brightness":
Computer display brightness: want daylight-friendly (200-1000 nits) or sunlight-readable (1000+ nits).
Low-Cost Windows Software:
Equivalents of Microsoft Office ($250+):
Best free software, from 12/2005 issue of PC World magazine
Lower-cost replacement for Intuit's Quicken: MoneyDance
Free software if
you're connected to the Internet:
Google Docs and Spreadsheets
(saves to HTML, Word, etc, on server or on your disk)
My original experience:
I use a laptop on my boat, and never connect it to the internet. I use floppy disks
to copy files between my laptop and computers ashore (in libraries or internet cafes).
This works well except that:
- About half of the public libraries won't let you put a floppy disk in their machines.
- Most public libraries don't support FTP (needed sometimes, for web site uploading or
- Some internet cafes are high-priced or user-unfriendly.
- Software companies are starting to build an assumption of constant-connectivity into
their software, automatically checking for updates, etc.
- Some software downloads are too big to fit on a floppy disk;
have to use a file-splitter program to chop them into pieces.
My later experience:
I use a laptop on my boat, and use Wi-Fi to connect it to the internet (taking the laptop ashore
to an internet cafe, or sometimes getting a Wi-Fi signal right from the boat).
This works well except that:
- I once had horrible problems with viruses and spyware and trojans, to the point
where I had to reinstall the operating system. Make sure you have installation CDs,
do backups, and install anti-virus and firewall and anti-spyware software.
- If connecting from the boat, try aluminum foil or a metal can to help
the antenna get more signal.
Later, I bought a Blueproton GSky Wi-Fi adapter, and am very happy with it.
May not be the best, but seems very good and was cheap, and the simple fact
that it is at the end of a 4-foot USB cable instead of being attached to
the side of the laptop makes it much more effective than my old 3Com card-adapter.
But it does not work with a USB-extender cable; limited to the built-in 4-foot cable.
Still later: a number of those Blueproton GSky Wi-Fi adapters have died on me, one from
being dropped, another maybe because of heat. Switched to a Rosewill adapter. It also runs hotter
than I'd like.
How to repair a scratched CD-ROM (from Ideas of the Week Newsletter from Idea Exchange):
- Get a clean, soft cloth and wipe the disc from the center outward with
straight spoke-like strokes.
Do NOT wipe the CD in circles; this will cause more scratches.
- Next squeeze a miniscule amount of toothpaste onto the scratch.
With another soft, clean cloth, rub the toothpaste into the scratch
and then remove any excess.
- Polish the CD with a chamois cloth and any petroleum-based polishing
solution -- Armor-All, clear shoe polish, or Vaseline.
Wipe in straight lines from the inside out.
- Finally, squirt a drop of Windex or another water-based window
cleaner on to the CD and wipe with yet another clean cloth.
Does not work with CD-RW's, only CD-ROM's ?
From Bob Hardin on the Yacht-L mailing list:
Many liveaboards report that CDs absorb moisture at the outside and inside
edge. The causes them to corrode and become worthless. They seal the edges with
nail polish and other such things. Seems the edges are just cut out and not sealed.
From Bob Stewart on The Live-Aboard List:
One of the brightest, low cost, office lcd monitors is the CMV CT-522A
15" LCD Monitor w/Speakers. It has a brightness number of 450 cd/m2
and I've heard of cruisers using this model under dodgers and in the
companionway. This does run off 12 volts.
From "How-To: Recover from a Soda-Spill Disaster" by Alex Castle
- Act fast; don't sit around moaning about it.
- Maybe turn device upside down, to stop further penetration.
- Turn it off / unplug it.
- Remove batteries.
- Assess the damage.
- Wipe up.
- If needed, disassemble the device. Maybe take pictures as you do so.
- Wash it off. Maybe with alcohol swabs. If large area is soaked, run it under soapy water,
then rinse with water (distilled best), then dry with fan or gentle hair-dryer or just air-dry.
- When completely dry, re-assemble.
- See if it works.
From "Low-Tech Fixes for High-Tech Problems" article by Paul Boutin on NYTimes.com:
Batteries keep their charge longer if you keep them cool.
If you get your cell-phone (or other electronics) wet:
Take the battery out immediately, to prevent electrical short circuits
from frying your phone's fragile internals. Then, wipe the phone gently with a towel,
and shove it into a jar full of uncooked rice.
It works for the same reason you may keep few grains of rice in your salt shaker
to keep the salt dry. Rice has a high chemical affinity for water — that means
the molecules in the rice have a nearly magnetic attraction for water molecules,
which will be soaked up into the rice rather than beading up inside the phone.
[Other people say this is wrong; rice isn't particularly absorbent, and rice keeps
salt loose because it slides around inside the shaker.]
Crashed Hard Drive:
If - no, make that when - your PC's hard drive crashes and can't be read, don't
be too quick to throw it out. Stick it in the freezer overnight.
"The trick is a real and proven, albeit last resort, recovery technique for some
kinds of otherwise-fatal hard-drive problems," writes Fred Langa on his
Windows Secrets Web site. Many hard drive failures are caused by worn parts
that no longer align properly, making it impossible to read data from the drive.
Lowering the drive's temperature causes its metal and plastic internals to
contract ever so slightly. Taking the drive out of the freezer, and returning
it to room temperature can cause those parts to expand again.
That may help free up binding parts, Mr. Langa explains, or at least let a
failing electrical component remain within specs long enough for you to recover your essential data.
[Heard elsewhere: the "rice" trick is a bad idea. Rice has a lot of powder with it; you don't want
that getting into your device. And rice absorbs water it is in contact with, but not water "out of the air".
You're better off drying the device as much as possible and then letting it air-dry the rest of the way.]
[From a Chris Gayomali article: "If you use dry rice to resuscitate a wet phone, don't touch the power button
for at least 24 hours, no matter how much you're tempted to."]
From jar311 on reddit
If you drop and fully submerse/drench your phone in liquid:
DO NOT check your phone to see if it works, unless you want circuits to short immediately and screw yourself with zero recourse available.
DO NOT throw it in a bag of rice.
You will need:
- As much silica as possible (raid your suitcases, wife's shoe boxes, ikea flat packs, electronics, etc.)
Keep this stuff when you find it. It's handy!
[Maybe can buy silica crystals in 2 kg bags in the kitty litter aisle of your supermarket.
Also may be sold in craft or hobby stores. May be sold as "flower dessicant".
Pharmacies may throw away a lot of this stuff; ask there.]
- 1 Tupperware or Ziplock bag.
- Isopropyl Alcohol (optional, mostly). 90% to 100% concentration, not 70% or something.
[Maybe could use electrical contact cleaner instead ?]
- Paper towels.
- Dish towels.
- 1 salad spinner.
(Or a pillowcase, whirled around your head, carefully.)
- DO remove all accessories, batteries, and sim/memory cards.
- If your phone was dropped in sugary liquid (and ONLY if dropped in sugary liquid),
completely submerge your phone in 100% rubbing alcohol (yes, I'm actually serious).
You want to avoid the alcohol part if you just dropped it in water as you run the risk
of dissolving adhesives inside the phone. If it was dropped in yesterday's glass of coke
you'll be just as screwed if you don't do this step as your phone WILL ultimately stop
functioning from the sugar residue, so the iso bath is worth the risk and SHOULD be done.
- Lay your phone in a bed of paper towels or dish towels in a salad spinner if possible.
If you don't have a salad spinner available it's not the end of the world, skip step if needed
[or use a pillowcase, whirled around].
Place phone on side against wall of spinner with screen facing the centre of the spinner,
we want the liquid pulled away from the screen and towards the battery area.
- After a good amount of delicious centrifugal force has been applied (couple minutes, tops)
in salad spinner, shake that phone like your life depended on it (keep a FIRM grip or it
will end up as a decoration lodged in your drywall) until you're not getting spray out
of it with each shake.
- Place in ziplock bag with screen facing UP with as much silica gel
as possible for TWO DAYS without breaking the seal. If you have enough silica gel packets,
pack the battery compartment with them and place around all sides of phone.
Get as much coverage as possible. DO NOT CHECK ON IT FOR THE ENTIRE TWO DAYS.
Silica is wicking moisture and we want this the entire 48 hours without interruption.
- While your phone is doing its drying thing, clean contacts of the sim/memory card with alcohol wipe or isopropyl and paper towel/whatever.
You want to start this process as quickly as possible, get that thing powered OFF. Circuits start blowing pretty much immediately.
While this process works well, a lot of the time previously-wet phones are still ticking time-bombs,
especially if exposed to moisture while turned on (which is almost always) and left on for too long after exposure.
You may notice buttons start to go, camera gets wonky, etc. That being said, I have many people who have no
problems in the future at all. It's a good process and I swear by it.
And remember make this process AS FAST AS POSSIBLE.
Proper disposal of old electronics and batteries:
Some manufacturers have recycling or disposal programs; check with
your local computer or phone store.
"Fix a man's computer, it works for a day.
Teach a man to fix his computer, and he'll call you tomorrow saying he deleted system32."
See "Theft recovery software" section of my Computer Security and Privacy page.