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.