Thank you for your replies. I might well have a software
issue because, although the unit is new, the latest firmware fitted is dated Aug 06.
I have asked the SH helpdesk to assist, but not expecting to solve it before sailing to France
across the TSS this coming Friday night!
It looks as though I will have to take my transportable AIS set as a backup. I find that a 'flight case' aluminium box with GPS
and AIS Rx inside and a whip antenna attached to the box works adequately (Ranges of, say 8 miles) unless it is raining and the sails
are wet and therefore highly attenuative to RF. [If that happens, I rig an antenna in place of a pennant!]
Thankfully testing ashore is simple as I can receive one shore station and up to 30 ships from the comfort of my home office!.