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new school (gps) knotmeter do they exist?

7K views 11 replies 8 participants last post by  Minnewaska 
#1 ·
Hello all

I have a traditional knot-meter on my boat, the impeller works just fine but the instrument is dead. I would like to replace it with what I call a modern day knot-meter, something that has the display of a traditional knot meter, an approx 4 inch display, but get's its data from gps. Does such a thing exist?


Basically a GPS with one goal, to display land speed using the traditional knot-meter type display??

- I under stand the difference between a gps reading of boat speed and boat speed measured by a knot-meter. Boat speed over land, distance traveled, is what matters to me not thru water speed.

- I can and do use my handheld GPS for this but I would like to replace my "dead" knot-meter display with something that roughly fits the opening without having to install or use the existing impeller.


Thanks,
John
 
#3 ·
tommays

Thanks for that, just what I am looking for. For others see;
SpeedPuck - Velocitek

I think, at 4 1/2 inches in dia i can make it work.

Not that I want to appear greedy in my request but does such a thing exist with the more traditional, needle (analog) type display?

John
 
#4 ·
Problem is that the Speed Puck is about the same price as a low-end chartplotter.
 
#5 ·
Dredging up an old thread to see if any new options are available.
Basically, I'm looking to replace an old knotmeter with a non-transducer setup, so a gps-based model.
Really just want speed display with an odometer, which is what the old unit has. Seems tough to find such a basic model.
Speedpuck is close, so are Velocitek products, but I would prefer 12 volt power over batteries, and also a more permanent mounting method.
Strange that I just bought a GPS for $150 that has all sorts of stuff I really don't need, but can't find super simple display to mount on the bulkhead.
Any new products that I have overlooked?

(Also, Speedhut has some nice gps-based units that would fit the bill, but their stock ranges are more for cars, etc.)
 
#8 ·
For me it's exactly the opposite. I really don't care how fast I'm moving through the water, it's much more important to know my SOG. Heading south to Bequia from St Lucia last year, we encountered a very strong north bound current. The GPS showed 2.2, 0.5, 1.1, 0.7, 0.5 knots, etc. while the boat speed through the water would have shown well over 6 knots. That would have been very deceptive and of no value in the days before GPS. As it was, barreling along at better than 7+ knots, we were getting nowhere fast and what usually takes us 6 to 8 hours, took 22. Having both adds a lot of information, but if I could only have one, I'd take SOG.
 
#7 · (Edited)
Yes, as others have hinted, really the most economical device that would do what you want would be a cheap chartplotter. Then you are getting all the chartplotter info too.

Another option : handheld GPS on a bracket, with 12V supply going to it.

Third option : one of the modern MFDs (Garmin GMI 20 et al) connected to GPS receiver.

Fourth option : GPS watch.
 
#9 ·
A Raymarine i70 is can be used as an intelligent display for just about any data on a SeaTalk ng/NMEA 2000 bus and may be the right form factor but at a little more than $500 plus the cost of putting in an N2K BUS I don't think it's cost effective. Add an analog/N2k adapter and a GPS and you can display both the speedometer as well as SOG. I think you can also get an i70 System Pack that includes the Wind, Depth and Speed transducers but, again, we're talking bigger dollars than most people would be willing to spend to solve your problem.

As many others have said, a cheap GPS will give you all the info you say you want.
 
#10 ·
Hey, thanks for the replies to this resurrected thread.

I know that my handheld GPS or chartplotter will do what I want, but you have to toggle the buttons to get to the correct screen for one value; then toggle back to get to the other screen for the other value. Sometimes each toggle takes a few keypad strikes. Not a big deal, but not where my focus should be, or what I want to do on a casual sail. SOG is fine for my sailing area, and, as far as "i" stuff and apps, I don't do that, it's a principle thing.

To clarify, it would be nice to see a display with just two things on it, speed and odometer, fixed mounted on the bulkhead, powered by 12 volts, no transducers. One screen, two fields of info.

On a short daysail it's nice to leave the harbor, glance at the screen without hitting a button, check the OD and know when it hits X.XX I should think about heading back. Glancing at the screen for speed info is also nice. And it's also nice not having to bring an extra device on board if I don't need it.
My stock analog knotmeter device from the 70s has this basic view, which is the same data that has appeared on every car I've owned (see image). Just strange that no modern systems offer this without having to toggle around. It's just an annoyance knowing that they have so much information available, and they have to put it all in every device, but the only two things I want I have to dig for.

Speedhut and Livorsi make what I want, but the their scale won't work at the low speeds of a sailboat.
 

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#11 ·
Most chartplotters will display speed in the corner of the display, so no toggling of displays. But it still clutters up the display, which is why I have an MFD on the sea hood, where everyone in the cockpit can see it. I have it set up to display GPS speed, depth, and paddle speed (gets the GPS speed via NMEA 2000 from the chartplotter, but it could also get it from a GPS puck).

You can see the display I'm talking about, half way through this video. Note 1.5 to 2 kts difference between true and through-the-water speeds.



So what you want is available, at a price.
 
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