Speedometer Connected to GPS Device?

[76SeaRay]

Is there such a thing as an analog (or digital) speedometer that gets its speed information from a VHF Radio or Fishfinder with GPS instead of the water pressure tube?

 

[Alumarine]

Not sure if there is but you can get a speedometer that uses gps for speed info.

https://www.iboats.com/shop/searchrabbit/result/?q=gps+speedometer

 

[dingbat]

Is there such a thing as an analog (or digital) speedometer that gets its speed information from a VHF Radio or Fishfinder with GPS instead of the water pressure tube?

Yep...

GPS SPEEDOMETER (FARIA INSTRUMENTS) - iboats.com

GPS SPEEDOMETER (FARIA INSTRUMENTS) - Since 1998, iboats is the most trusted water lifestyle online store for boat parts and accessories, boats for sale, and forums. Enjoy great priced products with fast shipping.

ww2.iboats.com

 

[76SeaRay]

Great, thanks for the info. It looks like the Sierra Eclipse Black Domed GPS Speedometer is what I need. It has the NMEA 0183 connection for getting the GPS info from my other instruments. I do need to decide whether to get the 35 or 60, cruising boat with 5.7L vortec and alpha one gen one.

 

[H20Rat]

Why

Great, thanks for the info. It looks like the Sierra Eclipse Black Domed GPS Speedometer is what I need. It has the NMEA 0183 connection for getting the GPS info from my other instruments. I do need to decide whether to get the 35 or 60, cruising boat with 5.7L vortec and alpha one gen one.

Why even bother with the NMEA connection? There are plenty of GPS based speedo's, and using NMEA doesn't save you any cost, just added complexity/wiring.

 

[76SeaRay]

I have a hardtop mounted GPS antenna for best accuracy and reliability. Both my Standard Horizon VHF Radio and Garmin Fishfinder have NMEA 2000 and NMEA 0183 capability so why not use them. I am an electrical engineer so wiring is not big deal.

 

[dingbat]

I have a hardtop mounted GPS antenna for best accuracy and reliability.

Side by side comparisons over the past 15+ years.... no quantifiable difference whatsoever in position accuracy.

Reliability is a different story. On my third remote antenna in 15 years on my primary MFD.

Have since configured network to utilize backup MFD (internal antenna) as the primary source of position data. Remote antenna is backup

 

[Scott Danforth]

VeeThree and Faria both offer GPS speedometers (VeeThree sells thru Sierra here on iBoats)

I have 3 issues with GPS speedometers:

• they are only marginally more accurate than a pitot tube
• they cost more than a pitot tube
• they wont last 30+ years until I get bored with the look like a pitot tube

However they exist

with your plethora of electronics

I have a hardtop mounted GPS antenna for best accuracy and reliability. Both my Standard Horizon VHF Radio and Garmin Fishfinder have NMEA 2000 and NMEA 0183 capability so why not use them. I am an electrical engineer so wiring is not big deal.

I would go with a glass cockpit like new boats

NMEA 2000 fish finder and display

you could even look at this to control everything on the boat from the NMEA displays https://www.veeconnect.info

 

[KD4UPL]

Have you checked your "regular" speedometer against a GPS? I have and it's only off by 1 or 2 MPH. That's far closer than it needs to be for my use.

 

[Bob Sander]

Is there such a thing as an analog (or digital) speedometer that gets its speed information from a VHF Radio or Fishfinder with GPS instead of the water pressure tube?

Older thread but....
I installed a 10 inch Android head unit. It's a cross between an android tablet and an automotive car stereo. It also contains a gps and has wifi ability. It's actually built for a car but it works in the boat too.

Being an android tablet with a remote gps antenna (I placed the antenna on the front deck wide open to the sky), you can download any gps speedometer of your choice from google playstore. You can also download and run any nav app they have, compass app.... etc. The head unit also has backup cam ability, as with most aftermarket car head units these days. With a camera switcher I have a forward cam on the bow, a reverse cam on the stern, and an engine bay camera. It all comes out on one simple 10 inch screen.

If your boat has OBD2 ability then you can also download torque pro from the playstore and display engine data directly on the head unit. Of course it has all the other stuff any car head unit has too... blue tooth phone calls.... yadda, yadda

You can set the home screen up any way you wish. Here I have a compass on the left, clock in the center, and GPS speedo on the right.

 

[Lou C]

I recently fixed my old pitot tube speedo, and it is pretty much in agreement with the GPS on my Garmin but doesn't really start reading till 10-15 mph. Just have to clean out the tube every so often.

 

[Bob Sander]

I recently fixed my old pitot tube speedo, and it is pretty much in agreement with the GPS on my Garmin but doesn't really start reading till 10-15 mph. Just have to clean out the tube every so often.

Yeah, if you already have a pitot tube system then you may as well continue to use it. I don't think there is any serious advantage to a gps system other than the fact that you don't have to poke more holes into the transom. gps does work in reverse too, but I think that amounts to little more than talking points!

 

[dingbat]

I don't think there is any serious advantage to a gps system other than the fact that you don't have to poke more holes into the transom. gps does work in reverse too, but I think that amounts to little more than talking points!

Unless you boat on a river or tidal water

Drifting with current at 4 kts. = 0 mph on a pitot tube
Head into the current at 4 kts. = 9.2 mph on pitot tube

Makes it rough when you want/need an accuracy of +/- 0.5 mph or less