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.