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For a quick up date on my sub
"Persistence."
I revamped my thruster controls to what they should
have been in the first place. I had relatively light relays controlling
the motors. After many hours of use they started sticking, both on and
off. Pretty scary when you're spinning around in a marina next
to docked hundred thousand dollar boats. I was going to switch to
solid state but decided to stick with mechanical relays, only use heavier
ones. It's fine now.
I've been diving the sub in relatively shallow
water for a year. Finally, I'm going to do a deep water test. It's
time to get out-a-da baby pool and in-ta-da the big pond. In a
week and a half we're supposed to take Persistence up to Seneca Lake in New York
State and do an unmanned deep water test. It's going to be weighted thirty
pounds positive to go to 550 feet on a line. After sitting on the
bottom for an hour, a second smaller line is pulled to release sixty
pounds of weight and Persistence now thirty pounds negative, will come
back to the surface......if all goes as planned. If it doesn't, well, we
won't think about that right now.
Ah yes, Underwater communication! I
have a request of you electronic types.
I have been researching several methods of
communication between my sub and the surface. There are three methods
I came up with.
One is to have a radio transceiver, VHF or CB type,
in the sub and a coax cable to the surface with an antenna on a float.
It's relatively cheap but there is the drawback of
the cable dangling in the water to get caught in a thruster. Also,
I've been told that after running through 350 feet of cable there won't be much
of a signal radiating from the antenna. Another drawback
is coax cable is big and bulky to store on a reel on the back
of a small sub.
Method two is almost the same as method one except
with an intercom in the sub and a twisted pair of very small wires going to the
surface. The unit is also cheap and it has the advantage of
very small wires going to a surface float so 350 feet of cable will store
easily, but to communicate, a surface boat has to actually get to the float and
plug in their half of the intercom. Also, there is still the chance to get
the wire wrapped up in a thruster.
Now for the big bucks! The proper way to do
it is to have an acoustic type underwater telephone. I have tried to
transmit from the sub with a walkie talkie and it's good until you get about two
feet deep. The radio frequency electrical signal gets absorbed into
the water and that's the end of the contact. An acoustic telephone uses
high frequency sound waves instead of electromagnetic waves as a carrier.
Since sound transmits through water quite well, they work fine.
I know there are commercial systems out there to be
purchased, but for a personal sub, they're way high in price. I was
wondering if anyone knows of a system for communicating that might be in a
P-sub price range or, is there anyone out there that has the know how
to design a system that can be built by someone with a little bit of
electronic knowledge and a soldering iron.
Captain Kittredge had an acoustic system
designed and they built a few of them. I understand they worked reasonably
well but that was thirty years ago. With the advances in electronics, most
of the components he used could probably be replaced with a few IC's.
Does anyone know of a reasonable priced system out
there or, is anyone knowledgeable in this area
and willing to take on the challenge of designing something. I'll do the
building but I just don't know what to build.
Thanks for listening, Dan H.
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