In article .com,
"jmorash" wrote:

....

thanks for any suggestions
--Jim Morash


Jim, I've read through the responses you have had and allow me to inject
some real world additions. You see I work for the Navy and we have built
things a lot like what you are talking about and getting the antenna
some height above the water is a requirement. It's actually rather easy
to do. A simple fiberglass mast will do it, counter balancing the added
weight is easy, since there needs to be enough mass below the surface to
balance some sea state conditions


Here is a link to the Newport tracking system
http://www.npt.nuwc.navy.mil/autec/barts01.htm This isn't the one we
did, but if shows you some ideas

The system people I work with developed, use a different buoy system
but works almost the same.

I did some experiments with antennas (900MHz) just as sea level (OK 3
feet above) and could still get a solid connection at about 1 mile, when
I raised them to 6 ft I got a solid connection at 5 miles.

Other considerations.. the antenna mast whips a lot and makes recovery
(in rough water) a little interesting. There is going to be a switch
from the simple ground-plane antenna to a disc-cone due to the danger
the ground radials pose.

We also found that putting a LED based flasher on the bouy a real
good idea (to see it in low light conditions)

--
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Thanks Ralph, good to get some actual numbers on use of 900MHz at sea!
I'm not sure if we can quite manage a 6' mast (this is not a buoy, but
a mobile vehicle) but clearly more height is better. We already use a
strobe to see the vehicle at night, it does help a lot.