GPS speed accuracy

FreeBeeTony

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
I recently purchased an Icom GP360ML cartplotter.<br />Used it on the boat for the first time yesterday and was surprised at the speed indication. Said we were only going 20mi/hr. Felt like we were going faster. How accurate is this indication?
 
1

18rabbit

Captain
Joined
Nov 14, 2003
Messages
3,202
Re: GPS speed accuracy

The next wave of technology is just on the horizon. Airmar is making an ultra high frequency transducer that will accurately measure the speed of debris (air bubble) passing below it in the water. As soon as someone implements the math to process the Airmar input against a GPS input, you will have actual speed (SOG), current flow speed, and the boat’s speed in the current. Personally, I have little use of all the data but you know someone with too much money is going to want it. :)
 
T

ThomWV

Senior Chief Petty Officer
Joined
Dec 19, 2003
Messages
701
Re: GPS speed accuracy

Last fall I switched to one of the super high performance Airmar transducers for my own boat and found myself in need of a separate speed and temperature sensor. I had seen the information on the new no-moving-parts speed sensors so I asked if one made sense for me. The lady at Gem (the retail outlet for Airmar is a company called Gem Electronics) about it and she sort of chuckled. It turns out they run right around $700. I opted for the standard bronze paddle wheel and temperature version and saved myself about $500.<br /><br />By the way, the GPS doesn't care if you are turning or not when it makes its speed calculation. A boat can't turn sharp enough to make a speed difference for the GPS. They are typically accurate to 0.1 MPH and most refresh the speed calculation once per second.<br /><br />Thom
 
sloopy

sloopy

Commander
Joined
Jul 12, 2002
Messages
2,999
Re: GPS speed accuracy

What goes 200 miles an hour and makes a sharp turn and will not kill you?
 
Boatist

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: GPS speed accuracy

FreeBeeTony<br />They are very accurate for speed over the ground. Does not know speed thru water. In a body of water with out much current you will not find anything more accurate.
 
You must log in or register to reply here.
Top