I'm getting into this conversation rather late, but until March, I used to work on a rather similar project: We put these little robot boats into the middle of the Atlantic and had them listen for an impact of a missle during a submarine launched ballistic missle test. Neat stuff. During this job, I had the opportunity to be at sea for 5 weeks (on a ~300 ft oceanographic survey ship) supporting it and I have a few observations- 1. Don't count on solar power. It is very often cloudy at sea, and infrequently full sun. if the seas get calm enough for your solar panels to stay above the water for a while, you're going to get a nasty layer of salt dried on top of them which kill the efficiency. In fact, everything above the waterline will have to survive and operate with a layer of salt on it. 2. The waves in the middle of the ocean are just big enough to be annoying- usually between 3 and 5 feet (pk-pk) and relatively long wavelength. This motion will serve to work harden virtually any antenna scheme you have. Unless you are in a storm. Thats where you find the biggies. 3. The sea is incredibly corrosive. Anything that doesn't corrode is going to get scum on it. We saw the beginnings of corrosion to the aluminum and steel in less than 10 hours of deployment, and even the stainless steel screws started to corrode after a while. 4. Don't count on moving around under battery power. Out little boats were small (about a foot wide, 3 feet deep and 3 feet long, with pontoons for stability) With 2 trolling motors to steer it with differential steering. This could keep us in one place against 2 knot currents for *maybe* 48 hours. This is with 160A-Hr of batteries (about 200 lb.) 5. We had differing opinions about marker lights at night- all big ships at sea are expected to have them. I don't know how your little boat falls under these rules. We put a single while marker light (10W, I think) on a mast. 6. Your little boat could be considered a hazard to navigation. If someone does find it, realistically there is no way to prevent them from picking it up and taking it as a "service" to the other ships at sea. 7. Abandon all hope of VHF or higher frequency radios back to a land based receiver. We needed bandwidth, so we used 900 MHz radios, which got us about 10 miles from an antenna 2 feet above the water to an antenna 90 ft. above the water. If you have a GPS trained clock, you can synchronize the two receivers pretty well and get some pretty impressive operation under bad S/N conditions with modulations like spread spectrum. Matt And to keep it appropriate for the PICLIST- I put a couple of PICs on it- 2 12C672's, which served as the motor PWM controller (with a bunch of MOSFETS) and a scuttle controller if we had to abandon them. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.