Paid project: build a boat engine temperature logging system


I have an old wooden boat with engines that overheat sometimes. the engines have temperature gauges but they are not very accurate.

I’d like someone to build me a simple, cheap system that has five sensors, that i can then attach to five parts of the engine. ideally i’d like to be able to see the temps in real time and save the data, on a pc laptop, but happy to hear other alternatives

i’ll pay for any parts (from core electronics of course) and time to build it.



Welcome to the forum.

I can think of several ways to skin the proverbial cat.

You should probably think about the temperature ranges you need and perhaps how they need to be attached to the engine, for example, do you need to monitor EGT’s within the exhaust manifold and or coolant temps within the expansion reservoir or tap a sensor under a hose clamp etc etc.

These things will dictate the type of sensors you use. Saving the data to an SD card in a CSV format would be easy, as too would outputting to a small display.

Another thing to consider is how you will power the device, for example, small batteries, or 12V / 24V from the engine.

Happy to provide a bit more advice if it would help - I built something a little bit similar a year or two ago for my old 1954 Landrover.


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Hi Jon

thanks for the tips, they all sound good.

I’ve just got this boat a year ago and trying to learn all things nautical, so right now my head feels too full to get around arduino etc, which is why I’m looking for someone to build this for me.

on the specific points:

  • i dont want to put any sensor inside the exhaust or inlet pipes, so they would all be under hose clamps etc
  • temp range is just from say 20C to 110C
  • power could come either from a pack or i can run wire up to a 12v outlet on the helm (boat-speak for dash)
  • output ideally to a display so i can track in real time on the helm, either a specific screen or into a laptop or android phone

but, as i said, I’d really like to pay someone to build it for me…

Next questions for you to consider…

  1. How far away from the engine is the place where you’d like you screen? This could determine if you can use (longer) wires or need to transmit between devices (perhaps one near engine and one on the helm.
  2. How big would you like the screen? Bigger = more expensive and generally speaking requires more power to display stuff on it.

These two things are potentially at odds with your requirement of “cheap”.

As a general thought, reading, writing and displaying the data is the easy bit. Making the project appropriate to its surroundings (cable runs, box & screen size) etc etc is the harder part.


Hi Jon

Engine is only 1-2 metres from helm. The furthest sensor on the exhaust might be about 2m away and then 1m up to helm so wire might need to be 3m

Screen can be small-

Re cheap I had been expecting to pay around 150 if doable more if needed

An additional twist was that the boat actually has two engines. I was going to just measure them one at a time but if the system could take. 10 sensors in total that would be great. Sensors seem to be 2-5 $ each ?

Finally, do you know how tachos work ? If I could plot rpm alongside temp that would be perfect. If not that’s fine I will just track manually .


David Marcus

My advice would be to use thermocouples for your temperature sensors - The DHT & DS18x20 variants are good at recording temps but are not conducive to sliding under hose clamps. The thin nature of a thermocouple wire is ideal for your situation; perhaps these:

Problem is they aren’t cheap because you also need a thermocouple amplifier for each thermocouple, like this:

There is some good news though…
I think Id suggest a Raspberry Pi Model 3B+ and have it run node-red. NodeRed will handle the charting of the data nicely for you and you could possibly use your phone to hot-spot to the Pi and watch the data from the browser in your phone / laptop (so wouldnt need a screen). Alternatively you could simply run a HDMI cable from the Pi to a screen (Raspberry Pi have a nice 7" unit).

There appear to be a couple of thermocouple plug-ins for Nodered too:)

As for my knowledge on tacho’s… Yes & No. On my old Land Rover diesel I used an opto-isolator connected to an Arduino - I finally got it working but the Arduino was a bit low on processing power. That solution would need to be re-investigated and converted to run on a Pi; not sure how charting / relating rpm to temps would be handled in Node-Red. Some tacho’s though have a W terminal on the back and that has the pwm signal popping straight out of it.

More food for thought I guess.


I have successfully got a RPi working as a wi-fi hotspot so Node-Red communications could easily be direct to your phone or laptop (rather than using a dedicated screen on the helm).

I will continue to look at Node Red connectivity directly to OneWire and SPI thermocouple amplifiers.


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