Marine/topo portable unit/maps

[mr2shot]

Having lost my reliable but basic magellan portable I'm in the market for a new unit to use on a small boat mainly in UK waters and also (as a bonus) for cycling. I like the look of the Garmin GPSMAP60 but am confused by the expense and possibly limited supply of maps.(I believe this unit is now discontinued in the US so hopefully prices will fall). I need only a small number of charts (solent/chichester harbour etc) but they must be reasonably accurate for ditch crawling or I might as well plot raw lat/long on a chart! Likewise ordanance survey/ topo maps need to have the equivalent detail to 1:50000 OS maps. I have a car charger outlet on the boat (but not on the bike!
I am totally mac orientated for computing so need something non pc!
Has anyone ideas for the most cost -effective future proof combination of hardware and mapping software?

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