Starting from scratch: which depth transducer/display for OpenCPN?

[redpointist]

My boat is on the hard and I need to figure out in the next month or so what transducer to replace the one I smashed out this winter.

My rambling thinkings so far: Definately want thru-hull since the hole is already there. Flush mount seems best. I'm leaning towards the DST800, but it comes in at least 3 flavors, nmea 0183, nmea 2000, and analogue. Obviously the nmea 0183 would connect easiest with OCPN, but I also want some kind of display in the cockpit. I thought I hit the jackpot with this budget friendly updateable nmea 0183 repeater, the CruzPro MaxRp110 (CruzPro MaxRp110 User Configurable Multi-Function Instrument). But then I realized I have no idea how I could get the display to show the depth corrected for keel offset or any needed calibrations. Maybe I just need to bite the bullet and buy a chartplotter that will accept nmea and be content with accessing the depth readings on the plotter and laptop instead of a dedicated display.

I don't have any instruments yet except from an Icom-M802 ssb radio. If you were starting from scratch right now and not wanting to spend thousands (shiny new plotters make it hard to resist but I'm trying to go older and used on ebay...but I could possibly splurge a bit...), which direction would you go with equipment choices in an OpenCPN friendly network?

[Neptune's Gear]

Do you currently have an nmea2000 bus? If NMEA0183, how do you intend to get the multiple data streams (gps, depth, speed? AIS? etc) into your pc for opencpn?
Long term, nmea2000 is probably more future proof, but currently a bit more hassle and expense. Your answers will determine what I'd recommend.

[Neptune's Gear]

Thinking about this, do you have any other instruments? I think Id go for a B&G Triton display. It allows your depth calibration, and can display pretty much anything. The kit with the transducer is probably the best value at $1399 (you get a $150 rebate off this) for depth wind and speed. Not 2nd hand though (probably) but some good advantages on the old gear. Need a device like an at10 or a actisense to get NMEA0183 for the PC though. Anyway, that's what I'd do...

[Hakan]

redpointist...
You ask for opinions, here's mine;
If i were in your place and with the mind I think you have I should have gone for the wonderful repeater you've found. And if I couldn't find a way to adjust the sounder values for water-line offset I should have accepted that. (My own sounder signal is adjustable but I haven't for a couple of reasons.) You'll learn to use the depth figures for what they are, and will get some 0.3? meters safety margin.

But unless you've a serial port on your PC you have to use a serial/USB converter to get the depth NMEA message into OCPN. I should have connected one of the repeater's NMEA IN to TX and the repeater's serial OUT to RX on that USB-converter to OCPN. With that instrument you can then also get data from OCPN if you like. Like course, speed etc if you have the GPS connected to OCPN.

The other, looking to future, way around is to find a similar repeater instrument for NMEA2000, use a NMEA2000 sounder and connect them all to OCPN with a NMEA0183/2000 converter. But if that kind of repeater is available I don't know and it may be more costly.

Good luck
Håkan

[Neptune's Gear]

Håkan,
You dont need a repeater for NMEA2000 - if the data is on the bus, all connected devices can see it.... They may not display it if the PGN is unknown to them, but its there... So any multi display device (like the B&G triton) should be able to display most PGNs...

[redpointist]

Thanks for the replies! I have absolutely no instruments I intend on keeping except for an Icom m802 ssb. They're all old/broken proprietary sensor-display combos. I guess this really comes down to if I want to go 0183 or 2000.

You're right that the depth calibration might not end up being a big deal anyways. While I was thinking about it though I found this Simrad IS20: http://www.simrad-yachting.com/Root/...20222576_B.pdf

It has a nmea 0183 input and it says it has speed and depth calibration features, but I'm not sure the calibration works for any nmea 0183 input or only for 'Simnet' input. It looks like it might work though. It doesn't look so awesomly customizable and upgradeable as the MaxRp110, but it might be worth trying out, theres several on eBay for ~$200.

On 0183 vs 2000...The displays for 2000 are about $500 (the Triton T41 displays mentioned by Neptune above do look nice) rather than $200 for 0183. The PC interface for 2000 is about $200, but I'll only need 1 I think. The serial usb converters for 0183 are significantly cheaper, but I'd probably need several of them. Hmmmm....The future proofing and interoperability of 2000 might be worth it even if I have to buy expensive converters to interface with OCPN. But man if I go 2000 I feel like I'm going to end up spending a lot more money.

[redpointist]

Originally Posted by Hakan

redpointist...

But unless you've a serial port on your PC you have to use a serial/USB converter to get the depth NMEA message into OCPN. I should have connected one of the repeater's NMEA IN to TX and the repeater's serial OUT to RX on that USB-converter to OCPN. With that instrument you can then also get data from OCPN if you like. Like course, speed etc if you have the GPS connected to OCPN.

So are you saying it'd be possible to have the depth/speed/temp transducer AND the OCPN laptop (which would be getting GPS data from a puck or something) both connect to the repeater, so that I would have depth/speed/temp/ and distance/course to waypoint data all available on the repeater? With a multiplexer or something? Or would I have to choose whether the transducer or the laptop with gps data is transmitting? The repeater says this in the manual at http://www.maxvu110.com/maxrp110.pdf :

4 Input Channels and can search each channel for 2 different Sentences:
NMEA #1 input A
NMEA #1 input B
NMEA #2 input A
NMEA #2 input B
NMEA #3 input A
NMEA #3 input B
NMEA #4 input A
NMEA #4 input B

Which leads me to believe both the laptop with OCPN and the transducer could display on the one repeater display? This thing sounds so cool...it really makes me just want to go with 0183.

[Hakan]

Originally Posted by redpointist

So are you saying it'd be possible to have the depth/speed/temp transducer AND the OCPN laptop (which would be getting GPS data from a puck or something) both connect to the repeater, so that I would have depth/speed/temp/ and distance/course to waypoint data all available on the repeater? With a multiplexer or something? .............

Yes, I do think so. And there's a very competent multiplexer within OCPN. Whatever comes in to an OCPN port you can get out to another, or the same. There are also filters so you can choose what to receive and transmit on/to each port.

The Simrad IS20 option could be useful if cheap enough. I've the even more dated IS15 in my boat. Whether IS20 can off-keel adjust a depth value coming in through its NMEA port I don't know. But it can be worth a little investigation. I could try to check and come back if you don't find it yourself.

Håkan

[Hakan]

Originally Posted by Neptune's Gear

Håkan,
You dont need a repeater for NMEA2000 - if the data is on the bus, all connected devices can see it......

Matt... Thanks, that's truth of course but, as already replayed, there are no other instruments.
Håkan

[redpointist]

Originally Posted by Hakan

The Simrad IS20 option could be useful if cheap enough. I've the even more dated IS15 in my boat. Whether IS20 can off-keel adjust a depth value coming in through its NMEA port I don't know. But it can be worth a little investigation. I could try to check and come back if you don't find it yourself.

Håkan

Thanks! I didn't realize that IS15 existed. I did some reading on it and that led me to the IS12 which can be had very cheap. It looks like the IS12/15/20 all have economical displays that can show 0183 data. Seeing these, I think I'll go with a 0183 version of the dst800 transducer. That way, the transducer could send data to an IS12/15/20 and also interface with the OCPN laptop without expensive nmea2000 converters.