Just an update on the solar panel I fitted at the weekend. Today was a cloudy day and the battery was at 13.5 volts, which means the solar panel is doing a good job of maintaining a charge.
The Panel came off ebay:
The seller's items time out regularly and they relist, rather than extending the running time of the item like other sellers, so the link will eventually run out of time, but look out for the photo if you want the same panel.
I changed it slightly by fitting a long twin-core lead with a cigar lighter on the end so it just plugs into the boat's electrics. You may be able to make do with the 1 Metre cable and crocodile clips.
The thing is so efficient though I may have to fit a charge controller at some point.