posted 07-25-2014 08:01 PM ET (US)     

[A Raymarine a67] is available locally. It includes the charts but not a transducer ($130). I've looked at the charts and they are great for where I will travel.

Any suggestions on other units will be appreciated too.

Thanks,
Don

posted 07-28-2014 12:20 PM ET (US)            

--a GNSS receiver, of varying capability, some limited to just the USA Air Force NAVSTAR GPS and other more capable, and with various facilities for simultaneous satellite tracking (or "channels") and various update rates;

--a chart plotter of various sizes and color capabilities, brightness;

--embedded digital chart cartography bundled with the unit price;

--a SONAR, of various designs and performance, including conventional mono-pulse down scan, side scan, frequency modulated pulse compression, high frequency and high-resolution, and on and on;

--a transducer, of various size, power, frequency, beam width, and range;

--a NMEA-2000 network interface;

--an Ethernet network interface;

--an NMEA-0183 interface, of various number of ports, various speeds, and various configuration (single-ended or differential), with and without multiplexing capability;

--a multi-function display with abilities to overlay RADAR or AIS targets; and

--a touch screen display with or without conventional buttons.

I don't know of any method of assess all the options available and determining which one is the best choice based on some criteria, such as:

--lowest price

--most reliability

--most durability

--most logical operating system

--most adherence to standards for interface with other devices

--best after-sale support

--most compatible with personal preferences for size, color, appearance, brand, and so on.

There are just too many choices and too many categories for evaluation to ever reach resolution on which unit is the best or stands out from the pack.