Articles By Our Members
Submarine Watertight Compartment Drying Fan
by Bob Warburton, March 2006
For those with less than perfectly tight WTC's on submarines, a good idea
is to ventilate the compartment between runs in order to prevent
condensation problems from causing corrosion and moisture damage to
installed equipment. Here is my cheapie solution.
Ever wonder what to do with that burned out PC power supply? Well,
assuming the cause of the failure was not a dead fan, it is a good source of
a fan to start this project. Simply extract the fan and its wiring and also
cut out the grill from the back of the case to provide a finger guard for
the assembly. File off the rough edges of the grill and clean the fan
(almost certainly necessary if it is used).
Be sure to save the screws from the fan mounting, they are the easiest
way to remount the fan.
Obtain a suitable easy to work with case of your choosing. I used a
plastic margarine tub of the 454 gram (1lb) size. Instructions for that
Place the fan on the lid and mark the location of the screw holes with an
ice pick or other slim pointed device. Also trace around the inside of the
fan case with a permanent marker (marks easily on plastic).
Cut out the lid (roughly) and punch holes for the four corner screws and
a hole for the wires. Mount the fan to the underside of the lid with the
grill on the outside. Make sure the fan is facing in the proper direction
to blow air into the container. (on a PC, it blows out of the power supply
case) Lead the wires out through the other hole in the lid.
Trim around the inside edge of the grill with a hobby knife and punch or
cut a hole in the side near the bottom edge to accommodate a small hose
which you can lead into your WTC through a service port. The air hose
should not be too long, or airflow will be severely restricted. I found
that about 2 feet of 3/8" OD X 1/4" ID tubing was ideal for my application in
an AKULA model.
I just thread the hose through the access bottle cap hole, push it to the
far end of the WTC, and hook it up to a 12-volt power supply.
Warning: these fans will typically not take voltages over 14
volts, so hook it up to a regulated supply, not just an automotive battery
charger, the peak voltages will likely burn out the fan. A simple 3
terminal regulator IC such as an LM7812 would do just fine as the current
draw is typically only about 0.2 amps at 12 volts. The fans are not
reversible by switching the wire polarity, and may even burn out if reverse
connected, so be careful.