The problem turned out to be a defective aerial - water had got into the 'waterproof' moulding and run down the inside of the cable as if it were a pipe destroying its electrical charateristics en route. We were barely able to pick up Solent Coastguard in Portsmouth let alone anything further. Now with a new aerial and cable we can eavesdrop on French coastguards - which at least makes us feel as if we are in France even if secuely tied up in Blighty.
Bob from Greenham-Regis (an electronics company not a port on the south coast) also upgraded the autopilot software and for the first time the Raymarine kit now behaves more like an autopilot and less like a demented helmsman. Why do companies release half-finished software and then let customers discover the bugs?
The replacement Furuno cockpit plotter is now readable thanks to a new 'double-glazed' upgraded screen technology and the chartroom plotter is now talking to it's friend in the cockpit and exchanging 'sentences'. Techies reading this will know what that means - the rest of you may smile and look indulgent.
So we are all set - all systems are go - and as soon as we feel able to leave Mum and dad we'll be off.