Sanctuary and crew completed the Great Loop cruise in 2007. At that time, our primary chart plotter was a Raymarine RL70CRC. This system uses C-MAP chips in the form factor of the 1950s and 1960s airmail stamps; that is, rectangular in a 1:2 length-to-width ratio. The only place we found C-MAP coverage to be problematic was the Trent-Severn Waterway. That wasn’t because we couldn’t get a C-MAP chip to cover it, but the chip was expensive for the less than 200 miles between other chips, so we just didn’t bother. We used the Canadian Hydrographic Service (CHS) paper charts for the TSW, and they were just fine. Except for that 200 miles where we used paper charts, we relied entirely on the Raymarine system as our primary navigation
system. It never failed, not even once. We always had paper charts for backup, but we never actually had to rely on having paper charts. They were very useful, and we would not recommend not having them, but we didn’t have to actually rely on them.
The CMAP chips we used for our Great Loop cruise were:
NA-C323.08 – Wilmington, NC to Key West, FL to Panama City, FL
NA-C324.07 – Sandy Hook, NJ to Wilmington, NC
NA-C401.15 – St. Lucie Inlet to Lake Pontchartrain
NA-C202.01 – Rideau Canal, St. Lawrence River, Lake Champlain
NA-C302.15 – Cape Cod, Long Island Sound and Hudson River (This chip covers the Erie Canal,
both north into Lake Champlain and West to Buffalo)
NA-C102.12 – Lake Michigan, Lake Huron, North Channel and Georgian Bay
NA-C047.03 – Inland Circle Route: Chicago To Mobile
The “Chicago-to-Mobile” chip, NA-C047, had a couple of quirks. First, it did not cover much of the Cumberland and Tennessee Rivers. It’s title tells the tale: “Chicago-to-Mobile.” Second, the chip does not maintain it’s scale as you travel along. Generally, we would have liked a 3-mile scale, but that chip scale was frequently not available. We had no choice but to run on the 1-mile scale. Not the end of the world, just not what we would have preferred. Play
with that chip before you head into the rivers to become familiar with it’s quirks. It’s the only one that behaved that way.