Downloaded the software, made up the cable and uploaded the updated software tonight. What a difference it made. Tides work fine but will need to checjk the accuracy against the paper copies.
What did surprise me was all the additional features that the software provided.
I hadn't realised till now just how old the software installed was, nearly two years. How many folk just buy them and don't check, and mine came straight from Garmin this week so it hadn't been sitting in a shop for ages.
What does surprise me is that it was so old and Garmin are not sending them out up to date?