It seems reasonably priced although cheaply made - however it would need some work to make it 'boat proof' For starters it would need to be mounted into a waterproof case. Reliability on a RIB would also be a question mark - there are a lot of big capacitors on the main PCB which would be vulnerable to shock loadings - easily overcome by 'stress relieving' them with a bit of non corrosive silicon sealant
Using GSM text messages in this type of application is mature technology - in a previous job I designed systems like this for use in (amongst other things) underground power cable monitoring.
The first step really is to decide if it meets your needs, ie:
1. If it has alarm siren and strobe, is anyone nearby going to respond to it?
2. If it sends you text messages, are you going to be able to respond to them quickly enough? No good getting a text message to say your boat is being nicked if it will take you an hour to get there. I doubt the police will be prepared to turn out and check the boat for you if you call them.
3. Have you got a GSM good signal at your boat's location? One system I setup in a factory in Bridgend needed an 18dB gain aerial on the GSM modem (think TV aerial size) to get a reliable signal - not an option on a boat.
4. Text messages are not 100% reliable, so not ideal if time is critical (eg someone is nicking your boat NOW). How does the system deal with this? The system I designed would send an alarm message every hour until it got an acknowledgment.
5. Can you check the system is operational without going to the boat? The system I designed would send a 'system ok' message once every 24 hours so that you would know it was still operational, and you could call it up to check on it as well.
There are quite a few similar systems out there - eg:
which claims to be waterproof (IP66)