GPS question.

[Falcone]

I have just added to my GPS collection with a garmin GPSmap 450 chart plotter, does anyone use one of these or similar with the preloaded marine charts???
What i would like to know is how much difference is there between the software used in the range of different branded GPS systems.

For instance last year i was given some charts with numerous wrecks on i had 2 GPS on my boat, a garmin and an eagle now if i programmed the same lats and longs into the 2 GPS and i said GO TO the results would differ
Now on the charts i was given last year i have entered the lats and longs of Seaham Pier into the GPS and it puts me inside seaham dock, and when i enter the lats and longs of the wrecks i was given they can be around 20-50 metres out from the ones pre programmed into the plotter.

Ive done a little bit reading up and the general consensus is that its down to the software the different brands of GPS use, im not sure?

 

[Kev1n]

In theory the coordinates from any plotter should match up. The thing that you need to watch out for is that they are both based on the same chart datum. Most modern coordinates are given using the WSG84 standard, which your plotter should be set to. It sounds more complex than it is in practice.
You can add a wreck position as the Lat/lon coordinate directly read from one plotter and typed into the new one. If they are the same make, the data may be transferable with a memory card like an SD card for the Garmins. Waypoints from other manufacturers’ plotters will be written in a different electronic file format (same lat/lon numbers though). You may be able to find a program on the ‘net that can convert from your current file type to the one your new plotter uses.

Another way would be to keep the existing plotter as a back-up and use it to guide you to the wreck when you can mark the coords in the new plotter.

 

[Codfather]

The garmin info on my plotter from the data card is pretty good, the wrecks symbols are usually very close or on the actual wreck. Info I add from diving books and the like are usually a bit out, so need a bit searching with the fish finder.

Pretty impressed with the garmin info tho.

 

[Falcone]

thanks for that lads, ive spoke toa few people and they have basically said what you said, lets just hope the wreck info programmed into the plotter is pretty close to the mark.