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ambianceack 03-09-2007 11:14 AM

gps vs chartplotter
 
what are the differences and similiarities between a gps and chartplotter?

PBzeer 03-09-2007 11:22 AM

As I understand it, a stand alone GPS merely gives you positional data (lat. long. speed, altitude, etc.) while a chartplotter puts that information onto a chart, giving you the ability to show a track, chart a course and use and enter waypoints. Or, in a different way, a GPS tells you where you are, a chartplotter tells you where you've been, and where you're going.

Freesail99 03-09-2007 11:25 AM

Both should be used as a back up to a paper chart.

Tubsmacker 03-09-2007 11:40 AM

My boat has a GPS (old model), something that I avoided buying when flying aeroplanes around as an 'Old School' seat o the pants type of aviator. Now the boot is very much on the other foot as a 'greenhorn' sailor. I am thinking of buying one of the Yeoman plotters, rather than a colour chart plotter. seemingly they are supposed to be easy to use and as they use existing paper charts, they don't require database purchase. If one is going to have papercharts as a backup anyway, it seemed a logical solution.

Does anyone have any experience of these devices?

Freesail99 03-09-2007 11:44 AM

One major difference is that the Yeoman would be it is used at the navagation station, where as the chartpotter would be used at the helm.

TrueBlue 03-09-2007 11:49 AM

A chartplotter depends upon coordinates provided by a Global Positioning System antenna/receiver. The chartplotter is integrated with and reliant upon the GPS to function properly.

camaraderie 03-09-2007 11:55 AM

Tubsmacker...I tried one but took it back. My little W&P chart protractor and a paper chart are all I need. The yeoman was just a PITA to deal with in the cockpit and I like to do my navigating from there rather than down below.
(I do have an electronic chartplotter...but I rely solely on paper in a lot of places as I am too cheap to buy more carts! )

camaraderie 03-09-2007 11:58 AM

TrueBlue...even though it is paper chart based....the yeoman relies on GPS as well. Full details here:
http://www.yeomanuk.co.uk/prodmar/maxi.htm

Valiente 03-09-2007 12:00 PM

The Yeoman was a very good idea for its time, and may still be for those with a certain discomfort with the technology of chartplotters or computers. But depending on where you sail, you can do quite well with a coastal navigation course, a decent handheld GPS with a 12 VDC plug (as they eat batteries), and updated and corrected paper charts.

Just be aware of tricky things like "does my GPS agree with the chart datum as listed on the chart I am using?" Going from a large-scale to a smaller-scale chart for the same area...and not noting the different datums...has put many a GPS-wielding sailor on the reef, for instance. Eyes, ears and even smell trump little flickering and occasionally fictitious numbers.

It's the habits of mind that cause navigational errors in most cases. The best way to use a paper chart is to read it and plot your course away from land and reefs, and then to note a couple of waypoints on your GPS that are free from obstruction. Account for lee and tidal effects (this can be noted in the useful cross-track or "XTE" function of even the cheapest handheld GPS), and you can sail safely in most situations, given an updated chart and the ability to coastal pilot.

Chartplotters are only as good as the charts they summarize, which in some cases are awful in detail and in others are outright wrong. Better in my mind is to use a PC laptop with a scanned or "raster" chart which is an exact representation of a real paper chart, rather than the "vector" charts that the chartplotters tend to use (although there are exceptions). Vector charts have their uses, however, due to the ability to zoom in to features that are easy to miss on a screen representation.

My choice is PC and paper and to avoid the proprietary cartridges of the chart plotters. My experience is that some skippers pay more attention to the creeping movement of the little boat icon of the chartplotter than they do to the sea around them. Needless to say, this is not only a grave navigational error, but also turns the experience of sailing into, in part, a glorified video game.

No thanks.

Good luck. Play with these gadgets at West Marine, and view the simulations. But if you just coastal cruise, I think paper and GPS and plenty of practice alone will suffice.

TrueBlue 03-09-2007 12:12 PM

Cam,
My post was responding to ambianceack's question, but that Yeoman device seems like an easy method of plotting your vessel's position on paper charts - if you lack a chartplotter. I do agree with your approach to navigating though.

We keep our planned course, paper charts out on the chart table of the pilothouse, where we also have a chartplotter. But most of our navigating while sailing is done from the aft helm, where our 2nd plotter is located. Paper charts would be very inconvenient to use back there.


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