Two of the Essential Questions are "Where are we?" and "Where are we going?"
Other Essential Questions include "When will we get there?", and "Will there be lunch?" After all, sailing is all about eating in new locations. But you have to get there before you can enjoy your lunch. And you have to get back (at least for now, while we have day jobs.)
While we need basic information, this can rapidly devolve into nothing more than an attractive nuisance. We can throw too much technology at the problem.
Once upon a time the core navigational skill was piloting. A coastal pilot identifies their position based on landmarks and deduced reckoning ("Dead Reckoning.") We also call this plane sailing because it uses plane geometry. ("Plain sailing" would be misspelled.) Doing line-of-sight sailing over short distances, the earth may as well be flat.
And all those compass-and-straightedge things you learned in 10th grade math suddenly become really, really important. [It seems that whole point of Math 9, 10 and 11 in the New York State education system falls into place as core skills for navigation. Really.]
Later, the skill set grew to include celestial navigation. Over the last few centuries sailors have perfected a number of devices to find their latitude by observing the altitude of Polaris over the horizon. This doesn't require much math. In the 1770's Harrison's H4 Chronometer made it possible to find longitude, raising the mathematical bar, and introducing spherical trigonometry to sailors. Read about Harrison and Maskelyne -- good stuff.
[For the purposes of celestial navigation, the earth may as well be the center of the universe. It's funny how sailing leads us back to geocentric and flat-earth systems.]
In the mid-90's GPS was introduced as a way to pinpoint a location almost anywhere on earth by receiving and comparing satellite signals. The theory is quite elegant. This page, Details of GPS Position Calculation, provides an overview. This page, GPS Overview, provides more details. [Yes, the titles don't match the content very well.]
In 2000, president Clinton announced that the "Selective Availability" of GPS signals would be turned off, making civilian GPS signals much more accurate and useful. Geocaching became a sport and mariners rejoiced. GPS prices fell because they became useful.
Red Ranger came equipped with a venerable Garmin 75. Once the state of the art, it doesn't hold a candle to an iPhone with iNavX. The current version of that GPS is something like the GPSMAP 78sc or the GPSMAP 62st. Both of these can tell us where we are and where we're going.
But nothing's ever that simple.
A core part of navigation is noting your position on your chart. The little circles and lines of where you are and where you've been make it possible to visualize where you're going. The traditional approach is compass, straight-edge and pencil on big paper charts. This applies 10th grade geometry to real-world problems.
Indeed, even with whiz-bang electronics, this paper charting is still absolutely essential. Electronics are fragile and depend on electricity -- itself a fragile commodity. Our neighbors at the marina (on Soul Mates) were hit by lighting and had all their electronics fried. They had to find land the old-fashioned way with paper charts and compass.
While charts are a essential, a nice color LCD display is a delight. The problem with the hand-held GPS units is the size of the display. Other than that, power consumption, accuracy and usability are outstanding. The tiny screen reduces their utility.
The current approach is to buy a complete set of charts on a micro SD card. This is a physically daunting pile of paper. There are several vendors for these electronic charts (C-Map, Navionics, BlueChart). The card is plugged into the chart plotter and the current charts are immediately available. The GPS signal locates your boat on that chart. A prudent mariner still makes a pencil mark on paper every hour or so. But for the other 59 minutes, you have a clear, crisp color display of where you are, where you've been and where you're planning on going. You can plan your luncheon.
Like all modern electronic marvels, there are dozens of competing products. Simply choosing a chartplotter and GPS is a complex job. It involves a great deal of hand-wringing. It's important to strike a balance between need and nuisance.
For the nerdy, here is a 4,000 word report, GPS/Chartplotter Selection for Whitby 42 #188 Red Ranger: chartplotter.pdf. For the deeply nerdy, here's the product-by-product comparison spreadsheet. Really. chartplotter-table.pdf.
[Yes, I wrote a huge whitepaper just to choose a GPS/Chartplotter. I'm that kind of nerd.]
After 13 pages of hand-wringing, I think that the Standard Horizon CP300i chart plotter and the Standard Horizon Matrix AIS GX2100 radio are a killer combination that can be installed with minimal complication. I think this will tell us where we are and where we're going.
We like the idea of single-vendor solutions. We both work in IT, at places where "best-of-breed" integration is considered a good idea. Picking products from multiple vendors is a lot of work with very real risks that the integration will not succeed. Indeed, CA asked about a "benchmark" for the Standard Horizon solution. Benchmarking is a common practice when doing this best-of-breed integration. When purchasing integrated solutions from a single vendor, there's no need for benchmarking to reduce risk. We both like Apple's model of seamless "everything just works" integration, and we're pretty sure that Standard Horizon will measure up.
This is not a "complete" navigational system. It's not even close. Indeed, we're not sure we want a complete system. Raymarine, Simrad, Furuno, Lowrance and Maretron (among others) have very sophisticated networked sensors, displays and controls. We don't think we want this level of complexity.
Eventually, we need to replace the Benmar autopilot. We will also need to replace our wind instruments. That seems to be it. Our ancient speed and depth sensors seem to reliable.
It seems like fun to build a complete (and complex) system. But Cook and Columbus crossed oceans without the benefit of working clocks. They had the advantage of a crew, which is why an autopilot and windvane make sense. Beyond that, too many fancy electronic toys may be more of an attractive nuisance than a need.