Cut Me Adrift - The Solution

Well I was able to test the prototype gizmo today.

It works..

It has a little Wireless Sender Unit which is about the size of a 50p piece and which needs to be attached to a fixed object like the bank or mooring and a Receiver Unit which is mounted on the boat.
The "Sender" can be attached to a tent peg and pushed into the bank next to the moored boat or hung from a low branch on a towpath tree or bush.

The Receiver Unit is a small fixed box powered from the 12V supply on the boat and which has a little adjustment thumbwheel and an internal sounder/buzzer.

It's simplicity itself to use.

You switch the sender unit on with its mini-switch and place it in its waterproof capsule, before placing it in a hidden position on the bank. It makes no noise and would be difficult for a yob, intent on untying you, to detect.

You switch the Receiver Unit on - it beeps to confirm that it is in wireless communication with the sender. You rotate the thumbwheel back until it alarms and then reverse the wheel slightly until the alarm stops again.
The sensitivity is now set for the distance between your boat and sender.

If the boat is untied and starts to drift away, the alarm in the Receiver Unit will sound as soon as the wireless contact is broken with distance.

It's possible to set the allowable distance to about 3m for example (the distance between the "sender" on the bank and the Receiver Unit on the boat). As soon as the gap increases by another couple of metres (by the boat drifting), the alarm will sound.

If you are onboard, asleep, the buzzer will wake you and alert you to the fact that either your lines have been cut or your pins have been dislodged from soft ground by another boat passing etc.
If you plan to leave the boat unattended by going to the pub for the evening, the gizmo can be attached to the SMS Message Unit mentioned in my earlier blogs and it will text your mobile to tell you that the boat is adrift...

I will post photo's of the unit when I've finished tidying the prototype up.