You would want door contacts for the doors of course. I would recommend
dual-tech motion detectors if you are going to use them to keep false alarms
down. The IR has to be set off as well as the micro wave for it go in to
alarm. This means that light or heat that would set off the infra red would
not set off the microwave. A bird that would set off the microwave (
Motion) would not set off the infra red but a human walking would wet off
the infra red heat and the micro wave motion. I would also recommend going
wireless to keep from having to run wires and it would be easier to move the
sensors later if wanted. The alarm system can be connected to the dock
phone line to dial out to where ever you want or it can be local on the boat
only and sound an alarm there.

There are many possibilities of ways to do this. I would start with what
you want the end result to be and design backward. It is easy to do.

John Mears
"Panama" wrote in message
...
I'm looking for design ideas and components for an intrusion alarm for
the boat. A friend bought 2 IR xmit and 2 IR receiver units to mount
in the cockpit, but my thought is that irregular sunlight bouncing off
waves, etc is going to set this arrangement off.