http://www.rogermisty.com/Roger's%20Programming/bms.htm
Boat Monitoring System Support Pages
This is a do it yourself project. You assemble the hardware from off
the shelf components. You can write your own software or use mine.

http://www.rogermisty.com/Roger's%20Programming/Boat%20Monitoring.htm
"Boat monitoring, and remote boat monitoring in particular, is an
evolving industry. Similar to a home alarm system the boat monitoring
system “watches” the boat and sends an alarm to alert the owner to a
negative event."
"Quick Overview
This project creates hardware and software that will transmit alert
and periodic email messages from your boat. It also provides the
ability to have one event trigger another, for example, if the bilge
pump has been running a long time to turn on a booster pump while
notifying you of the problem. The hardware uses off the shelf
components. "