Depth Sounder (fish finder) on RC or semi-autonomous boat

I have been working on an RC and autonomous model boat for a couple years (polystyrene block). It has an arduino nano brain, a cheap Neo-6m gps, and Honeywell HMC5883L compass break out board and two rc servos. I really want to add a depth logging function (to map little inlet areas on lake superior and plot in Open CPN).

There are a couple of portable depth sounders that would be a great addition to my boat (good size and power consumption) if I could get some simple single number data from them. They both transmit over WIFI to their own proprietary mobile apps. The Deeper Pro+ (which has its own gps) and the "luckylaker".

My questions for the community:

  1. Can anyone help reveal a strategy or starting point for getting a meaningful depth from either device so I could log it on my arduino sd card (with time stamp and gps location).

  2. Is there any hope of decoding the WIFI info sent out? Picking it up on some kind of wifi shield not a smartphone (having never played with wifi this is a stretch for me probably)?

  3. Might there be a way to hardwire the depth sounder to the arduino basically using their sensor and skipping the transmit and receive?

Unless you are quite familiar with electronics and communication protocols, hacking a device like those might be quite a challenge. And the Deeper Pro isn't that cheap. You can find sonar modules that are self contained and have a simple RS232 interface, which would be straightforward to use with Arduino.

You have probably seen this project https://www.robotshop.com/letsmakerobots/sea-rendering
which uses a commercial sonar.

The program logic not mind blowing. It’s the sensor the problem. I’m not aware of an Arduino friendly water depth sensor. If you can find one, start there.

If you can’t.. then ur in the business of reverse engineering a commercial depth sensor system. It can be done. I’m not going to be able to help u.

Thanks. Yes I found the sea rendering article on "lets make robots" I can find no mention the sensor used. But I think its an Airmar probably and older one. Exactly what I want to do though.

So I found one solution that is documented: find an older depth finder that uses Nema 0183 (as suggested also) and connect to Arduino via SparkFun Transceiver Breakout - MAX3232. May still be expensive as these thru-hull style transducers are well made for yachts. But there's a great step by step here!

http://kingtidesailing.blogspot.com/2015/09/how-to-connect-any-nmea-0183-device-to.html

Unfortunately I think the newer cheaper depth finders have the form factor I need with a small water tight sensor (which is really hard to find just as a sensor by the way). Now I am looking at a depth finder product called "halk eye" that has a single number output.

Could I read the wires from the seven segment outputs with the arduino?

Has anyone seen a documented process of hacking a device just for a single number output. I.e. I don't want to get into how the device works to calculate depth I just want the output number.

Cheap 7 segment ebay depth finder "halk eye":

https://www.ebay.com/itm/HawkEye-In-Dash-Depth-Finder-Sounder-Transom-In-Hull-Transducer/382355026098?epid=1728228032&hash=item590622b0b2:g:IFUAAOSwiCRUfkKc&vxp=mtr

Could I read the wires from the seven segment outputs with the arduino?

With great difficulty.

LCD displays are multiplexed with a very complex waveform that ensures no average DC voltage across any segment. A few people have managed to tap into the segment connections, and reverse engineer the waveforms of such displays to get the data out.

Sounds like a good project.

I have the Deeper Pro + and today IV had the idea of intercepting the data sent over the WiFi (possibly with wire shark to start with) then convert this data to NMEA 0183 standard so I can use it with ReefMaster

The end goal would be something like an Arduino mini /raspberry pi nano that connects to the Deeper via WiFi and the computer.

The Deeper app will allow you to log the data while casting it around the lake and make a bathymetric map but the display is not as good as reef Master.

Reef Master:
http://reefmaster.com.au/reference2/index.htm?context=270

T200T:
Could I read the wires from the seven segment outputs with the arduino?

This may be an uncouth suggestion on the arduino forum, but a pi zero with a camera could pretty easily read a 7 segment display

FullOfBadIdeas:
The program logic not mind blowing. It’s the sensor the problem. I’m not aware of an Arduino friendly water depth sensor. If you can find one, start there.

You can use the DS1603L ultrasound sensor for depth of up to 2,000mm.

They're designed to be used as water level sensor, but mounting them in a way that they're at the surface pointing down gives you the distance to the ground. 9600 bps Serial output, very easy to read with an Arduino.

I would recommend you try the Lowarance 7 TI.

Here is a resource that helped me: Best Fish Finder for Small Boat - Specs, Features, Pros and Cons