Charts are absolutely essential. The National Oceanographic and Atmospheric Administration (NOAA) in the Department of Commerce produces the nautical charts that sailors live by.
[Back in '95, crap like this was spewed: "Downsizing Government: Eliminate the Commerce Department". Only a complete idiot could claim that the Commerce Department isn't essential for protecting the lives of sailors without a specific plan for NOAA.]
Once charts were only paper. You ordered them from the government. Then you could order them from private distributors. Now, we have choices: paper, raster and vector charts. We can put the charts into electronic chart plotters, computers and hand-held GPS receivers.
Paper is high-quality, high-reliability and high-resolution. They always work. They're easy to use. No batteries to fail in a paper chart.
One of the big advantages of electronic charts is route planning. Working out a long trip on paper charts is complex. Lots of places along the US coastline are covered by several charts at several different scales; so planning your course means transferring your plans from chart to chart. A complex and error-prone operation.
The NOAA folks recommend a fairly extensive list of software products that can view electronic charts. Which leads us to a detailed examination of charting software that runs on Mac OS X, and supports pleasant route-planning.
The top-shelf products are both from GPSNavX.
The remaining products are open source and need to mature, or don't have a demo available.
PolarView - Nice status plotting, but no good route planning
OpenCPN - OpenCPN's Mac OS X version not well supported; a full version behind. Nice route planning.
Maptech Raster Chart Software - The US Boating Charts product supports Mac OS X. However, with no demo and a purchase price of $199, it's hard to evaluate this product. So, I won't be looking at it unless the others totally fail to work.
The head-to-head comparison of GPSNavX and MacENC demos is challenging without an actual GPS to do some real chart plotting. However, we can evaluate the planning capabilities.
The user interface for GPSNavX and MacENC is very similar. To an extent, the choice comes down to how the map refresh works as we try to do route planning. GPSNavX requires selecting the next chart; MacENC switches from chart to chart automagically.
Switching during navigation isn't that interesting. At sailboat speeds, we have plenty of time to consider which chart to use next.
Perhaps it's just because I download it first, but OpenCPN's approach to showing adjoining charts seems slightly nicer than MacENC. Further OpenCPN has a handy graphical notation along the bottom to allow selecting among the different overlapping charts at different scales. This a very handy "switch to the more detailed chart" feature.
OpenCPN's route planning, however, includes total distance and -- based on projected average speed -- run times. This is the greatest feature. A 100 nm trip (at 5 kn) is a 20-hour ordeal. It's smarter to make this into 3 6-hour trips. OpenCPN tells us total run time to a waypoint, allowing us to easily look for nearby marinas or anchorages.
Neither GPSNavX nor MacENC seem to do this as simply. They do show distance between waypoints. We can add and multiply. But, having the Route manager accumulate this information is way, way cool.
Of course, we'll also order a few more paper charts as backups. The large-scale overview charts aren't as handy to have as the detailed, small-scale charts that one uses to find specific marked obstructions and aids to navigation near shore.