GPS Navigation System and MPH

[jeclarke]

I'm thinking about requesting a GPS navigation system as a Christmas present - primarily for use in my car. I understand that some GPS systems will tell you the vehicle miles per hour. If I get a system that displays MPH can I use it in my ski nautique to check the accuracy of the speedometer?

I was at Radio Shack earlier today and the salesman said that a GPS system will only display MPH if I'm on a road that the system recognizes and thus not when I'm in the middle of a lake.

Does anyone have experience with this? If it will work, what brand/model of navigation system do you recommend. I would be tending towards the lower end of the price scale.

thanks for the help.

[GoBig]

RE: GPS Navigation System and MPH

We've been using a simple Garmin handheld on our boat for years. Works great on the water and for calibrating the speedo. What brand GPS were you looking at? Here is a cheap handheld waterproof GPS receiver for under $100 that would work good for this purpose (assuming you don't need a big fancy screen displaying maps you don't need)...

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/280436/377%20710%201420/1420/Fixed%20Mount%20GPS%20/Primary%20Search/mode%20matchallpartial/30/WMPrice|0?N=377%20710%201420&Ne=1420&Ntt=F ixed%20Mount%20GPS%20&Ntk=Primary%20Search&amp ;Ntx=mode%20matchallpartial&Nao=30&Ns=WMPr ice|0&keyword=GPS&isLTokenURL=true&sto reNum=5003&subdeptNum=3&classNum=10881

[j2nh]

GPS

Any decent GPS unit will display speed as well as location. You might want to check the model to see how big the display is for MPH and make your decision based on that. You should be able to get a decent one for less than $200.

Your experience doesn't make for a very good advertisement for Radio Shack. Sad thing is that you ALWAYS have to do your homework when buying anything.

[AuMDLST]

RE: GPS

I have used my Garmin bike computer to check the accuaracy of the boat gauges - no problems or concerns even though I was on a lake and without the bike.

[SuperSquirt]

I use a Garmin GPSMap unit on my boat with the addition of the depth finder/transducer. The mph is 100% accurate when comparing it to the ZeroOff mph, and the depth is always accurate too. I highly recommend this unit because of its preloaded detailed maps of the lakes. I am sometimes paranoid of running into islands and shallow water, and this unit shows everything in detail, water levels, islands, sat photos. Check it out

[GoBig]

That is a creative iPod mount approach. Have you ever had any issues with cord wrap when you make a quick hard turn?

[AuMDLST]

Maybe the Radio Shack guy should understand what GPS actually is
"The Global Positioning System (GPS) is a U.S. space-based radionavigation system that provides reliable positioning, navigation, and timing services to civilian users on a continuous worldwide basis -- freely available to all. For anyone with a GPS receiver, the system will provide location and time. GPS provides accurate location and time information for an unlimited number of people in all weather, day and night, anywhere in the world.

The GPS is made up of three parts: satellites orbiting the Earth; control and monitoring stations on Earth; and the GPS receivers owned by users. GPS satellites broadcast signals from space that are picked up and identified by GPS receivers. Each GPS receiver then provides three-dimensional location (latitude, longitude, and altitude) plus the time".

We are talking about GPS devices not "Tom Tom" type driving navigation devices

[jeclarke]

AuMDLST

I am talking about a navigation system (tom tom, Magellan, etc with a screen and roadmaps) that I would use in my car but that I could use occasionally to check the speedometer in my boat.

[AuMDLST]

I was referring to a strict GPS unit not a nav unit. The nav units (if they do not allow simple turn on turn off function and acquisition of satellites without the input of direction function) probably will not work. I believe you can get a Garmin etrex for $99. Buy the nav unit for the car and grab one of those for the boat.

[Chris4x4Gill2]

Yes, the NAV units are simply a GPS reciever with preprogrammed maps loaded on them. They will show your speed regardless of whether you are on a road or on the lake. I have used tom-tom, magellan nav, and handheld Garmins with no problems

[Chexi]

2 words... Garmin Nuvi. Easy to use. Upgradeable like crazy. Portable. Will do your mph / speedo calibration perfectly (I've used one several times on 2 different boats). Can add lake depth charts to memory.