Comment Three things (Score 1) 340
A Yellowbrick sat tracker for two-way comms using the worldwide Iridium constellation, a Linradio software defined radio receiver plugged to a discone antenna, and a Toughbook with Navigatrix GNU/Linux.
Aside from the required GMDSS, GPS, radar and so on, of course.
Credentials: a few years as radio operator on ships going around the workd