NMEA speed to pulse converter

[Porthandbuoy]

Does anyone have any experience of this, or any similar bit of kit?

http://www.cruzpro.com/sog1.html

Converts $GPRMC 4800 baud standard NMEA 0183 data sentence from a GPS into a 12Vdc square wave, which can output to your log display. Say cheerio to fouled impellers and a hole in the hull.

 

[pvb]

Why not just view the speed on the GPS? If you do get the Cruzpro device, be prepared to fiddle about calibrating your log display, because their 22000 pulses per mile is rather different from many popular transducers. There's some info about it in this thread - http://forums.ybw.com/forums/showth...ymarine-ST60-and-ST60-Tridata-instrumentation

 

[prv]

My log display can show SOG if I want it to without any special box.

Mostly I prefer to have boat speed, though.

Pete

 

[nigelmercier]

I made my own http://www.ybw.com/forums/showthread.php?458725-Raymarine-ST60-Paddle-Wheel-Simulator

 

[RichardS]

Does anyone have any experience of this, or any similar bit of kit?

http://www.cruzpro.com/sog1.html

Converts $GPRMC 4800 baud standard NMEA 0183 data sentence from a GPS into a 12Vdc square wave, which can output to your log display. Say cheerio to fouled impellers and a hole in the hull.

The CruzPro is a good bit of kit as in the thread highlighted above by PVB. However, I'm not sure why you would want one other than to display true wind or get your ST60 distance log to actually work in the absence of a paddlewheel. If you only want to "say cheerio to fouled impellers and a hole in the hull" then just use the GPS data directly.

If you want the other stuff then the CruzPro is probably the simplest solution ... and calibrating the speed against a GPS reading takes a few seconds, especially with the Raymarine kit which will do it with one button press automatically using a built-in ST60 routine.

Richard

 

[RIBW]

Does anyone have any experience of ....... any similar bit of kit?

I wanted to display true wind on my Raymarine wind display (which doesn't have the option to use SOG) and also eliminate the paddlewheel.

I used a gadgetpool Seatalk <-> NMEA bridge, which optionally translates Boat Speed to SOG and vv. It has worked well for three years.

There is a new elaborate version but the old basic one I used, tucked in a box behind the panelling was all I needed.

http://www.gadgetpool.de/home/english/index.html

Cheers
Bob

 

[Porthandbuoy]

My GPS is 'downstairs'. All I have in the cockpit is a bulkhead mounted speed & depth display and a compass. The log impeller is not on the centreline and reads different on each tack. I've tried adjusting the angle of attack to average things out, with no real success. It's also very prone to fouling, so even before it stops working altogether it under-reads. For dead reckoning I would use my Walker trailing log on longer passages.
I have no wind instruments, other than a windex at the top of the mast.

The Cruzco SOG1 looks like it will give me what I want in the cockpit, SOG. I might just drop a hint and perhaps the kids can club together and get me one for Xmas.

 

[laika]

The Cruzco SOG1 looks like it will give me what I want in the cockpit, SOG. I might just drop a hint and perhaps the kids can club together and get me one for Xmas.

Understand that you want to re-use the existing display and that if this is what you want then fair enough. However looking at the last year's Cruzco price list, once you've added duty, VAT and delivery you're not going to get much change from £150. If you don't fancy of knocking up something DIY (per Nigels suggestion) is replacing the log display completely with a cheap GPS repeater an option? The NASA one is under £100.

 

[Yngmar]

Does anyone have any experience of this, or any similar bit of kit?

http://www.cruzpro.com/sog1.html

Converts $GPRMC 4800 baud standard NMEA 0183 data sentence from a GPS into a 12Vdc square wave, which can output to your log display. Say cheerio to fouled impellers and a hole in the hull.

Except that gives you SOG (speed over ground) not, STW (speed through water). Which will fool your wind instrument into displaying ground wind rather than true wind (assuming you're interested in doing this for the benefit of that display).

But I think we already had that discussion last time this came up. Just something to be aware of when you make that decision.

 

[RichardS]

Except that gives you SOG (speed over ground) not, STW (speed through water). Which will fool your wind instrument into displaying ground wind rather than true wind (assuming you're interested in doing this for the benefit of that display).

But I think we already had that discussion last time this came up. Just something to be aware of when you make that decision.

That's exactly why I said in post #5 that the OP might as well just use the GPS data directly.

Richard

 

[lpdsn]

It does seem a very crude way of converting SOG into speed through the water. There are various bits of kit out there that would simply convert NMEA sentences. The ShipModul Minilexers support VTG to VWH conversions.

And if you want to do it on the cheap, I'm sure it could be done quite quickly with a Raspberry Pi type solution (must be threads enough to describe how to do that already).

 

[RichardS]

It does seem a very crude way of converting SOG into speed through the water. There are various bits of kit out there that would simply convert NMEA sentences. The ShipModul Minilexers support VTG to VWH conversions.

And if you want to do it on the cheap, I'm sure it could be done quite quickly with a Raspberry Pi type solution (must be threads enough to describe how to do that already).

What is required is to convert NMEA sentences into the kind of square wave pulse that is generated by a paddlewheel at the same kind of frequency that a paddlewheel generates it, in order to fool the navigation system into thinking that a paddlewheel is connected so you do need fairly specialised kit. I'm sure a R Pi could do that although I've not seen a circuit, as can Nigel's home-brewed circuit, but it's not simple unless you understand the circuitry involved, which I don't. I paid £80 for the CruzPro device which is not cheap but it is easy to connect up as it requires just 4 wires ( 12V, ground, NMEA in and Squarewave out) and it is tiny and encapsulated.

Richard

 

[lpdsn]

What is required is to convert NMEA sentences into the kind of square wave pulse that is generated by a paddlewheel at the same kind of frequency that a paddlewheel generates it, in order to fool the navigation system into thinking that a paddlewheel is connected so you do need fairly specialised kit. I'm sure a R Pi could do that although I've not seen a circuit, as can Nigel's home-brewed circuit, but it's not simple unless you understand the circuitry involved, which I don't. I paid £80 for the CruzPro device which is not cheap but it is easy to connect up as it requires just 4 wires ( 12V, ground, NMEA in and Squarewave out) and it is tiny and encapsulated.

Richard

Are you saying the existing bulkhead speed and depth display he wants to use only reads pulses rather than NMEA0183 sentences?

 

[Porthandbuoy]

Are you saying the existing bulkhead speed and depth display he wants to use only reads pulses rather than NMEA0183 sentences?

Yes. It's a Nasa Clipper Duet. Two co-ax plugs, one for depth( no problem), one for speed (problematical). The Cruzco SOG1 looks as though it will do the job if the pulses per nautical mile is within the adjustable range of my existing kit.

 

[GHA]

Yes. It's a Nasa Clipper Duet. Two co-ax plugs, one for depth( no problem), one for speed (problematical). The Cruzco SOG1 looks as though it will do the job if the pulses per nautical mile is within the adjustable range of my existing kit.

You could have a go at making one for a fraction of the cost using an arduino. Nigels unit is undoubtedly more elegant but arduinos are easier, loads on online help programming which isn't that hard anyway. So at a guess you'd need arduino uno - fiver, rs232-ttl converter - couple quid, 12v / 5v USB power - couple quid, FET transistor - a quid plus a box to put it in.
Probably much easier to put together than you might think

 

[ldevitt]

Did you get the Cruzpro SOG1 operating on your NASA speed log?

 

[Porthandbuoy]

Did you get the Cruzpro SOG1 operating on your NASA speed log?

No. The 'nice to have' funds were eaten up by the 'must do this winter' jobs. The Cruzpro is slowly moving up the list though.

 

[RichardS]

Did you get the Cruzpro SOG1 operating on your NASA speed log?

Welcome to the Forum.

I got the Cruzpro working perfectly with my Raymarine ST60 system as detailed in the thread linked in post #2 by PVB above.

However, there was some understandable confusion in this thread about what the device is supposed to achieve and whether people actually need one.

However, if you do need a paddlewheel pulsed output but without a paddlewheel, a quick call to NASA to establish whether the NASA instrument can be user re-calibrated to accept an input of 22,000 pulses per mile should confirm whether the Cruzpro is suitable. I was easily able to re-calibrate my ST60 but the NASA might not be as flexible.

Richard

 

[ldevitt]

Hi Richard, sorry I should have introduced myself, I work at CruzPro. We have been asked if we have a list of compatible displays this is why I asked if he had got it working.

As it happens we have a new version of the SOG1 the GPS Pulse (SOG2) this has a built in GPS receiver. We would like to release a list of compatible displays to help our customers, so we will be providing some free units to customers that want to test and confirm it works with their display. If anyone reading this wants to take part please send an email to info@cruzpro.com include the make and model of the speed display you have. We will be selecting based on first come first served to get a wide sample of different display types.

 

[Porthandbuoy]

Here's an update for anyone interested in getting their cockpit speed through the water (STW) display to read SOG.

Cruzpro very kindly sent me one of their SOG2 devices to try. http://www.cruzpro.com/sog2.html

What can I say? It simply does what it says on the tin.
The GPS reception is good and both my Standard Horizon GX2100E and Netbook running OpenCPN had no trouble interpreting the NMEA sentences.

The pulse output at 22,000 pulses/nautical mile is 20% more than the NASA paddlewheel log delivers. All I had to do to make my Clipper Duet read correctly was reduce the Log calibration factor by the same amount.

I now have what I want. SOG in the cockpit with STW and SOG at the nav table.