when I used to sail in England I had always on board a walker trailing log with a small box with 2 AAbatteries, as spare equipment. It was mechanic and electronic at the same time. I am looking everywhere to find it also second hand but it is desappeared. At the London boat show the chandlery stands don't remember about it and on ebay either negative research. Unfortunately I don't live in England actually so my unique chance to find it is throught the internet. Can anybody help me ?