Thank you all for your various responses..Let me expand some..It is necessary to access Maptechs website in order to register product..They do have a support there with FAQ's etc..From previous questions it would seem the problem is not uncommon, especially when interfacing with Raymarine equipment. This is normally configured as Seatalk bus. I spoke with Raqymarine at the boatshow, who said it could also be driven as NMEA.
Maptech have only test interfaced with ONE of raymarines products and say this SHOULD be typical of all. My enquiry here was to discover any EXACT info, as I think Maptech's is vague..On the subject of PC's aboard..At the boatshow, several makers/suppliers I spoke with, privately admit that the way forward in electronic nav is becoming and will be with PC..Mine is a notebook and if it gets wet at the nav desk I think I may have more serious problems than just PC....Thanks all for an interesting read..