An R/C clyde puffer I designed and built a few years back. It's not a particularly easy build, as it will most likely require modification. This was also before I got better at hull drawing, so there is some discontinuity in the hull near the bow and the skeg. Filler and sanding should sort that right out.

The motor it was designed for was about 30mm in diameter.

The steering is done via a servo under the wheelhouse mounted on the motor mount, attached onto a chain that runs through the two channels on the aft deck to the rudder (see photos)
On my model, I had a pair of ancillary chains on magnets that went from the servo up into the wheelhouse, and around the steering drum. This meant the ship's wheel would turn as the boat steered.

It's drawn from hull lines of VIC32.

LOA is 400mm, giving the scale to be about 1:50.

The rudder is intended to be glued onto a 2mm brass rod, threaded through the rings on the hull.
To attach the propeller, crossdrill the shaft and put a pin through both propeller and shaft.
I soldered my propeller shaft from 4 and 5mm brass tube, with a 3mm brass shaft. Take two short lengths (c. 5mm) of OD4, ID3mm tube and solder them into both ends of your 5MM shaft tube. This makes it fit a 3mm shaft nicely, whilst having .5mm all round for oil or grease. Helps to solder on an oiler tube perpendicular for refilling. There's a small hatch on the aft deck that you can align with the shaft oiler for ease of access.

The battery holder should accept a 3x18650 holder.
The perforated support component can be glued into the hull, and is intended to be used with cable ties to fasten various electronics in place.

For the nav lights, paint an LED first silver, then black, then white. Scrape off the paint (or mask before painting) where the lantern opening is.

The deck is recessed fore and aft to accept wooden planking. Use thick black paper on the planks edges to get a nice plank seam line.
Doors all receive brass hinge pins and door handles. Done right, they should be openable.
Sadly I lost the files for the cargo hatch planks, they were laser cut. Regular wooden strips with wee brass rings should work as well... or just cover it with a tarpaulin and nobody will know ;)

As for the mast, the mainmast should be about 258mm above deck level, and the derrick arm should be about 192mm long.

It will require a bunch of small brass wires and additional detailing pieces beyond what is in the files... that's up to the builder. Print a bunch of cleats and bollards, they are always good.

If you do make this, please please post a make. I'm very keen to see other people getting some use out of these files!

EDIT 11/11/2023:
I've added an updated version of the wheelhouse to this design. It's not perfect, but it's a huge upgrade to the previous old one, and I recommend using it instead!