Marine navigation on laptop?

You will also hear vector and raster in the world of graphic arts.

A raster is a fancy name for a bitmap image (Think photograph or a picture you scanned using a scanner). Yeh that's right, a scanner rasterises the image it sees into a bitmap.

A vector on the other hand is totally different and has its roots in pure maths because the image is described by a series of mathematical equations that plot each image. Vectors are smaller and can be scaled to any size without loss of quality. An common example of a vector graphic is a truetype font.

Street maps lend themselves to being vectorised (I use Odyssey Navigator) but topographic maps and marine charts are often produced as bitmaps or rasters by scanning the original paper charts. One popular raster mapping program is OziExplorer which I use and it allows you to scan a paper map and calibrate it by defining the latitude and longitude of a few points o the map (often the intersections of gridlines on the map). It supports a variety of industry standard raster map formats such as ECW and you can purchase or download from government sites many different maps and charts. I have about 20 Gb of maps for OziExplorer but the footprint of Odyssey vector maps for the whole country is tiny in comparison.

I sail on the Chesapeake Bay. These are my experiences using a laptop based chart plotter aboard my sailboat.

a) First and foremost, I usually find it to be somewhat impractical .. the screen is not visible at the cockpit in bright light. So, I basically use the computer to plan routes and generate waypoints for my GPS.

b) I find the laptop to be somewhat cumbersome with full featured software. There is just too much mouse clicking to functions buried deep in the menu structure. It gets somewhat stressful finding the cursor on a washed out screen and then remembering how to work the software with situations developing while under way.

c) I find the computer most valuable a night, during poor visibility or when I'm 'somewhat' lost (Heaven forbid that) or confused. So, despite my cited operational difficulties, I never leave port without it.

A few years ago, I've looked at vector charts. Back then, I found they required lots of customization and clicking to display the data I need. Somehow, I never could get the software showing exactly what I really want to see. Maybe I should revisit for current options.

So I settled on good old fashioned raster images of the familiar NOAA paper charts. Everything is in the 'picture' without a lot clicking to see it. Maptech software works well with the free NOAA raster charts and it doesn't cost an 'arm and a leg' to keep the charts current. Where possible, I hide the screen features I don't want to see maximizing viewing area.

But, I usually use a chart plotter that I programmed myself. It's a hobby project that's been ongoing for about ten years; a minimalist effort (not suitable for distribution) implementing only my essential features.

The chart occupies the entire screen except for scroll bars and the control/display bar at the bottom where the geographic coordinates of the cursor are displayed. When a GPS is connected, position, speed and course are also displayed on the bottom bar with a bullseye showing GPS position on the chart. When the right mouse button is pushed, there's a rhumb line drawn from the GPS position bullseye to the cursor with bearing and distance to the cursor displayed. Holding the left mouse button while moving from a start to stop point draws a rhumb line and displays bearing and distance between the points. Double clicking on the chart, generates a waypoint. Waypoints are formatted into a NMEA sentence that is recognized by my Garmin GPS for ease of entry.

Except for a chart select dialog box button and second seldom used button showing setup dialog for adjusting a few options, that's all I've found necessary as a recreational sailor.

--- CaptChas

I hope people don't mind me posting to these threads from last year...

MrUmbra's post is interesting, but opposite to my usage.

I charter 37' - 42' sailboats on the Canadian west coast and the BVIs. Most have a chartplotter in the cockpit, but rather than struggle with learning them I set up my 14" laptop below on the nav table or salon table. I have my planned route plotted and I can see it fine for general steering from the the cockpit.

I reply on paper charts and other publications for checking navigation hazards and other information, but I'm never alone on these trips so I have somebody to man the helm if I'm below looking at the PC or paper charts while under way. I haven't felt the need to try to set it up in the cockpit.