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Motorized kayak for hydrometric data collection

Dear forum members,

I created this post to share my motorized kayak building experience using several BR electronics components. Firstly, I want to set the context for the still ongoing project: as a water resources engineer living/working in Paraguay -a country blessed with an abundance of surface water resources- I almost always get confronted with a lack of available hydrometric data (flow, depth, etc.). Although there exist commercial survey packages for these types of measurements, locally there are additional challenges for which I prefer to build my own tool. Firstly, in addition to the already high cost of the commercial tools, importing them into Paraguay makes it a lot more expensive and cumbersome. Secondly, once one small piece breaks down or there is any need for reparation, you get stuck as locally there is no representation/support. The context of application is challenging, hence you don’t want to depend on sophisticated, third-party tools that you are not able to fix by yourself, particularly when you do not have access to spare parts (at a reasonable price and “as quick as possible” when you need them).

The majority of reservoirs, irrigation channels and rivers in Paraguay require a large and robust platform to cope with the waves. I have been following RB for already some years and I really like the compatibility and accessibility of their electronics components. Being inspired by earlier work on motorized kayaks presented and discussed on this forum, I decided to buy 2 T200 and a “kid” kayak. I decided not to drill holes in the kayak as I do not have experience with the waterproof closing afterwards. Both the propulsion part (on the backside) as well as the electronic cages are attached to an acrylic plate, which is connected at different points to the kayak by means of tie-wraps. In addition, bungee cords were used to increase the pressure. The sensors to be used can be attached on the bar foreseen on the frontside.


What took most time? The T200 were easy to connect/install due to the online tutorials. I spend quite some time in understanding better the “mixing” of channels of the RC control to operate 2 motors with one stick. I finally ended up using a V-tail mixer, so up to now I did not have to dig into the programming of the RC control. Secondly, it took me a lot of trial&error to be able to connect and run the ping sonar with Arduino MEGA (including local storage of measurements). My children allowed me to experiment in their portable swimming pool in our garden. During this period, I had a lot of issues with the data collection with the MEGA and ping sonar: it took a lot of time to initiate the ping sonar, and often it would never start reading although correctly wired. One hypothesis was that the water in the swimming pool was not deep enough (according to technical specifications BR site this is minimum 50 cm). However, sometimes it works surprisingly well, hence then it is always tricky to know what the problem exactly is. Although not having resolved this issue, I decided to take the kayak for a first trial in “open water”, being the Paraguay River the closest to where I am living (+/-1.000 m from the river side). I decided to firstly test the motorization. I did not have my swimming short with me and, although of a very short duration, this year winter is being very cold. But I had trust in the BR thrusters….Following short videos give some quick idea about the behavior of the kayak in the water:

There was some influence from waves generated from ships, but it performed well. Afterwards, I tried to get the ping sonar to work to test this as well (in deeper water), but I was not lucky and again the MEGA could not start reading the ping sonar. After checking today several recent posts on this topics, I guess the probability is likely that the software serial communication at 115200 baud rate is giving this problem, so I will try now with a hardware serial port. Once my “proof of concept” is functional, I would like to make a slightly smaller hull (for easier transport) and make the tool as “robust” as possible so it can serve for a challenging environment. I hope to come back soon to this forum and hear your suggestions/recommendations for this second step of the project….Thanks to all persons that in the past have shared their building stories: it really helped throughout the process when getting stuck.


As the story abuve was my first post, I was limited to 1 photo and 2 external links. However, I would like to share following video that contains the first testing done in the swimming pool in my garden

and the following picture of the platform during the test on the Paraguay River.

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Hi @ArnoudC, welcome to the forum! :slight_smile:

Thanks for this post, and the interesting information about your context, the process you’ve followed, and the challenges you’ve faced - it was an interesting read!

Hopefully switching to hardware serial solves this issue - it is known to be more stable, particularly at the higher baud-rates. If it’s still not working consistently after the switch, feel free to post about what you’ve tried and we can try to figure out what’s going wrong :slight_smile:

Beautiful photo - it’s always a bonus when testing takes you to lovely places

I’ve edited your post and comment so the videos are embedded, which lets us watch them from within the forum :slight_smile:

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Awesome project! (Video links are not working for me.)

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@ArnoudC you might need to allow embedding on the videos for the embedded links to work properly.

@hube268 in the meantime you should still be able to click the ‘Watch on YouTube’ link that appears when you try to play the video :slight_smile:

Dear @EliotBR, Thanks for the advice about changing the settings in youtube.

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Dear @hube268, Thanks for the feedback and pointing out the issue with the videos. It should be OK now.

Dear @EliotBR, Good news: using hardware communication instead of softwareserial between the MEGA and Ping Sonar indeed solved the issue (reference code: https://github.com/bluerobotics/ping-arduino/blob/master/examples/ping1d-simple/ping1d-simple-mega-115200b.ino ).

I hope to be able to go back to the river or another surface water to check it out.

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