The Ardupilot controlled transducer boat part 3

3689589361?profile=originalWith the help of several members of this community, I could make the prototype in the torpedo design work and I did a lot of measuring and mapping with it.

It went very well, so I decided to build an improved version of the sonar boat which you can see in the picture above.

But first I will share some impressions of my first boat. In the following picture you can see me with my "torpedo design" boat. 3689589386?profile=original



In the video below you can see the performance of the boat.

The ArduPilot worked very well and the speed, size and the operation range were satisfying. But the propulsion nozzle turned out to be very sensitive to sea plants. And in windy conditions with waves and in curves, it was rolling quite a lot. I measured a big lake with it as you can see in the Google Earth picture on the bottom of this page, but I decided to build a more stable boat.

So now I tell you about the Making of the improved boat:

The new boat should be able to carry more batteries, be more stable in the water, be faster and not be too much bigger. So I decided to build a small trimaran. I started to plan it with DELFTship which is for free and easy to use.

I also used NX to plan the space I needed in the hull as you can see in the pictures below:

3689589420?profile=original3689589526?profile=originalThe next step was the making of the positive mold. I could use the laser cutter of the Fablab in Aachen ( to cut the sections that were exported from DELFTship out of 3mm MDF.

3689589487?profile=originalAt home I glued everything together with hot glue and filled it with Styrodur that I cut before:

3689589441?profile=originalAfter a lot of grinding and filling, it looked like this:

3689589541?profile=originalAfter some more grinding and painting, I made a negative mold with plaster bandages to keep the costs low and painted it with 2K paint. After waxing the mold I could start with the glass fiber:

3689589562?profile=originalI used the following product and which worked very well:

The resin has a curing time of 40 min which makes it very easy to use. The result looked like this:

3689589607?profile=originalAfter equipping the hull it was ready for the water:

3689589670?profile=originalIn the following video you can see the making of the boat step by step:

Before letting the boat into the lakes I wanted to be able to find it after its work under any circumstance so I included an XBee 900 pro for a GPS-data link. Also I wanted to be able to manipulate the track of the boat by a joystick with the XBee, so I printed a case for a small remote control to include the XBee, a thumbstick, a small Arduino and other switches.

3689589587?profile=original3689589761?profile=original3689589632?profile=originalI am now able to switch between the XBee-controll and the ArduPilot with a multiplexer on board.

After that final step, I was ready for the next lakes.

After improving the ArduPilot parameters the trimaran performed very well. I could switch the boat on, put it into the water and have breakfast at home, before picking it up after several hours and it was always there. If the wind had blown it away, I could track it via the XBee and with the Earth Bridge, I could watch its position live on Google Earth.

In this Video you can see the performance of the boat in different conditions:

The following pictures will give you some impressions of the measuring:


In this last picture, you can see the work i have done so far with the boats and in the area, there will be many more lakes for measuring.

3689589784?profile=originalIf you have questions or suggestions just comment and I try to answer quick.

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  • Admin

    Hi Burkhard,

    As I posted at the beginning of this thread, I am using two size .60 float plane fiberglass pontoons that can support around 10 pounds (5kg). They are 38 inches in length (1m)

    I plan to mount the navigation equipment, radio, telemetry, sonar, and batteries on a bridge between the two pontoons.

    I purchased an early model Humminbird fish finder off of eBay for a reasonable price, however it is so old it does not have NMEA output and is fairly large physically compared to more modern fish/depth finders. I was hoping to detach the display from the transducer transmitter/receiver, but Humminbird will not release schematics and I will have to reverse engineer where to get the depth data and sync signals so I can build an interface to radio telemetry.

    I am beginning to think that I should just bite the bullet and buy a used Humminbird fish/depth finder that has an NMEA output and just process the NMEA strings to be sent out over telemetry to my shore based GCS.


    TCIII ArduRover2 Developer 

  • @Thomas J Coyle lll

    I guess you are right. I am quite happy with the results so far and i will stay with that configuration for the next trips.

  • Admin


    I bought the mbtelectronics side scanning sonar manual.

    You have to build your own transducer sled from Chinese ultrasonic transducers that have gone up considerably in price since the manual was written, build your own transducer transmitter, receiver, and power supplies. The mbtelectronics sonar is best suited to treasure hunters who have a good size boat to tow the sled around and hold the equipment.

    You would be better off buying a used Garmin or Humminbird sonar (fish finder) with reasonable depth capacity and NMEA depth and position output off of eBay rather than try and build the mbtelectronics sonar sled.


    TCIII ArduRover2 Developer

  • @Monroe Lee King Jr.:

    Thanks for the link. That is an amazing project!

    @ Trevor Strand:

    I started with the first boat about a year ago. But i could not really spend a lot of time for it and the lakes where I use it are very far away and i was there only 3 times with the boats.

    The Arduino that is on board collects the GPS and is looking after the string $GPRMC and logs it. Then it listens the sonar and searches for the $SDDBT string and logs it. In the document on the sd card, you will find the following after its done:



    The mapping software can handle that data. Thanks a lot for the link, i will test the program!

  • @Justin:

    I acutally thought about that as well but for huge lakes. It would be possible to supply the boat with solar power but i dont know anything about measuring depths of more than 50m. But you are right. Its a good idea!


    The sonar as a beam angle of several degrees. I guess you dont need a GPS resolution under 1m but it would be a good improvement! When I am done with the improvement of the remote control, I will inform myself about the  RTK GPS.


    What do you mean by return of the pulse? It is a closed system and it only gives me a string out with the informations about the depth and the temperatur.

    When my first boat was rolling a lot I thought about building a stationary mounting, that would hold itself horizontal with servo motors. But the new boat is really stable. The rolling that it still does is less than the beam angle of the sonar I would guess so I wil not need to calculate the angles.

  • Thanks for sharing! Amazing job

    How long did this entire project take you?
    Are there more details on the recording of your depth and gps recording elsewhere?

    What are your thoughts on underwater mapping software using your method?

  • Wow, that's a pretty impressive sonar project. @Tony Stark's Lab: Don't we all :) I have the copters laying around in a mostly empty lab, what I wouldn't do to get tools in there :)

  • @Monroe: It shouldn't be too hard. If you can acquire fairly accurate sonar sensors and use multiple points on your boat, you could triangulate the position of the sub in relation, and use that for navigation. For communication, I think a radio link would work for a short distance. Of course, you could always just tether ;) My roommate built a small remote controlled sub with a tether out of PVC, an acrylic dome, and some pumps from a fish tank for direction and buoyancy control. Doesn't need to be fancy, just work :) 

    @Burkhard: Great work! Very nice molding, I wish I could get anything that nice out of my molds. Great work on the boat, I look forward to seeing where you go with it next!

  • Very nice project. We could use a setup like this for our search and rescue.. Please check out our new website and give our new Facebook page a like..

    Also looking for volunteers. We are especially looking for someone with manufacturer connections to head up our donations department..
  • @Harry and Emlid:

    Thanks! Usually you do a negative mold out of glass fiber as well as you can see in the video below:

    But i feared, that i will never be able to seperate the negativ mold and the finished hull once its done, so i decided to make the negative mold out of the plaster bandages. It cost me about 20€ instead of around 100€ and i could rip the negative mold apart as soon as the rasin was cured. 

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