I've recently added a GSM alarm on my boat. I got it off Ebay for about $200. It uses a standard SIM (in the US that can be Tmobile or ATT). The SIM was free and has no contract
- I just pay $0.10 per SMS sent.
The alarm was meant for a car but works great on a boat. It has a temperature monitor
and a voltage monitor
. It sends an SMS to my phone
if either falls too far. I can also use my phone
anytime to send an SMS to my boat and it will respond with an SMS in a few seconds that tells me the status. It can also call other phone numbers to show that an alarm SMS was sent. When the boat's in a marina, I can use it to montitor the AC shore power
by telling it to send me an alarm if the voltage ever falls below 13v since that happens when the battery charger
The unit also has a bunch of other inputs that can be connected to a switch or relay on the boat - such as a water
level sensor, burglar alarm sensors, engine
ignition etc. It also has three outputs so that I can send a message to the boat to turn on or turn off something (haven't figured out what to use this for - I guess I could text the boat at night from the dinghy
to turn on the spreader lights when I can't find her.)
Some units come with GPS but I didn't get that since it uses power and I figured one of the other alarms would go off before the boat could be stolen.
This is the one I got.
GSM alarm AUTODIAL SMS Pager Home/House/Car/Boat/Moto - eBay (item 370263562090 end time Jan-19-10 10:13:09 PST)
There are others on Ebay - some might be better. If you are in the US be sure to get one that supports the US frequencies. Installing mine wasn't hard but it is a bit of a technical and wiring
adventure. You program by connecting it via USB to a computer that's running some downloaded software
Note: This alarm is no replacement for my first line of defense - someone local who has my cell phone
number who will keep an eye on the boat. I've also never had anything stolen off of my boat in 30 years of ownership
. Theft is pretty far down my list of concerns (leaks, fire, dragging, dead batteries, and being hit by another boat) are all higher.