Beacon Marine Security Limited (416/696-7555) has a unit called the HarborMaster Mark II. This system monitors the conditions described above and determines whether the boat is adrift, checks for explosive fumes, and monitors the boat's electrical system. Should an alarm be triggered, the system sounds an audible alarm and dials out, via a cell phone housed within, to a central computer system. The report is then transmitted to up to eight different phone numbers specified by you. These could include pagers, cell phones, friends' homes, the marina office, and so forth. The system also keeps a log of things like bilge pump cycles and battery strength so you can determine if, for example, your pumps have been cycling more than usual, which may enable you to fix a small leak before it gets big. This data, says Beacon, will be accessible on the Web, so you can sit at home while you monitor your boat in the marina. The system also contains a backup battery in case of total electrical failure for additional fail-safe capability. Marine Technologies International (941/272-5800) makes a similar system called the Aqualert, and Sure Action Inc. (800/648-4301) produces Marine Guard 2000.