Reg, G4FGQ wrote:
"The captain is pacing up and down the bridge waiting impatiently for a
radio message, cursing the poor fellow at the cable terminal 500 miles
away on the Scottish rocky Atlantic coast, who is sweating blood
twiddling knobs trying to balance the wideband, 0.05 to 50 Hz
reflection-coefficient bridge to within plus or minus 0.1 miles along
the artificial line and---."

O.K., plus or minus 25 miles isn`t close enough to find a sunsea cable
fault.

I`ve found broken pipelines offshore by placing an audio tone on the
pipe and grounding the second tone generator connection. The diver uses
a search coil to locate the tone on the pipeline and follows it out the
pipe until it drops off precipitously at the break in the pipe. This
works like gangbusters.

A cable is not necessary to communicate with a repeater on the ocean
floor. Acoustic (ultrasonic) communications work well at sea. Equip your
repeaters with acoustic communications gear and you can find them and
talk to them and get them to reporrt to you and to execute your orders
even if the cable is cut on both of their sides.

The company I served for 26 years found oil and gas in waters of ever
increasing depth. They then produced, transported, refined, and
distrubited the oil and gas and produvcts derived from the oil and gas.
This was one of the company`s many lines of business. We also were in
banking, insurance, farming, real estate, and manufacturing many things
including tractors, automotive parts. nuclear war ships, liquified
natural gas tankers, packaging, plastics, and at one time electronics
parts and systems.

In the deeper waters it became very expensive to install offshore
platforms so we switched to subsurface production and control facilities
on the ocean floor. We used acoustic location , status, measuring,
monitoring, and control facilities.

This was before global positioning systems (GPS) and every bucket of sea
water looked very much like any other. That required the acoustic
locating equipment. It amounted to a transponder that when interrogated,
responded with its reply that could be homed in upon.

We would travel by helicopter or boat to a location near the equipment
for data and control. We then dunked our transducer and used it to guide
us to our gear. Once we were stationed just over our gear we demanded a
status report. If adjustment were needed, it was so ordered and when
executed we got an updated status report indicating the successful
operation.

30 years ago when this operation was initiated, the available acoustic
equipment was nearly all designed for deep water as found in the ocean
depths. This is because it had been developed for the defense department
to keep track of Soviet submarines etc. We were initiating monitiring
and control using acoustics in water only a few hundred feet deep in the
Gulf of Mexico. So we had to pay for developing shallow-water acoustic
equipment. Fortunately this shallow-water equipment worked well in the
Gulf of Mexico, as expected.

GPS obviates the homing in on your equipment. You can locate exactly
over your equipment with very few problems.

Battery power can be installed for data acquisition and control on the
ocean floor even though the repeaters are powered from shore. The
acoustic equipment could be located at each repeater.

Web found batteries could last for about 5 years on the ocen bottom.
Ours had no opportunity for recharging. We found the battery was going
to perish from age in 5 years even though it is kept cool by its site
and a large enough battery is used to handle the discharge demanded of
the battery.

You could dunk a transducer near a repeater and interrogate for almost
any type and number of data points. You can now make the box smart and
program it to do all sorts of things. It could be designed to perform
various diagonistics on demand and to automatically store a variety of
information.

We traveled to the acquisition and control point. This might be avoided
by long-range acoustic communications as a "PlanB" just in case the
offshore point was hard to reach.

Weather in the Gulf of Mexico is usualy so good that you don`t have to
wait too long to make a trip out into the gulf. In the North Sea and the
Atlantic I think the weather is less good.

Best regards, Richard Harrison, KB5WZI