Tuesday, June 23, 2009

Navigation part 1

The first of a two part post, I thought I'd share a little on how I navigate. The second post will detail how I use the electronics (auto pilot, moving maps, radar) when piloting Lucky. This post will explain how I set waypoints and routes which I use while piloting.

In much the same way you'd put an "x" on a paper map to show where the closest Starbucks is, a waypoint is the same for electronic maps. Put a string of "x"s on the map and join them together - like a dot-to-dot drawing - to show how to get somewhere and you have the paper version of a route.

The picture at the top of the post shows me doing exactly that. The route shown is the part of the route between Cat Cay and Ft Lauderdale where we'll have to go through the cut between Gun Cay and Cat Cay, probably the trickiest part of the whole passage. Unless, that is, the Gulf Stream decides to throw 8' seas at us unexpectedly.

To create this route I use my laptop, running Raymarine's RayTech software. This is a free download that works much like their E120 screens but I can use a mouse and keyboard for entry. Plugged into the USB port is a special CF Card reader by Navionics that not only allows me to use standard CF cards, but also the encrypted CF cards that hold Navionics charts. Trying to read a Navionics chart in a standard CF reader will, supposedly, format the card. At $500 a pop, I'm not about to experiment to find out! One advantage of using the chart chip in this manner is the chart I use to plan the route is the same chart I'll be viewing on the E120 screen will piloting.

Although I plot the route using the electronic charts, I plan the route using the best paper charts I can find. For the Bahamas, that would be the Explorer set of chartbooks.

Once plotted, I pull out the Navionics chart chip and put in a blank CF card. The RayTech software then allows me to export the waypoints and routes onto the card in a format readable by the E120. Putting the CF card, now with a data file on it, into the E120 allows me to import the file into the plotter.

Its a pretty straight forward thing to do and well worth the 30 minutes or so it takes to do each time we're planning a passage.

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