I drawed this Tug using Tinkercad in last days. Size is almost maximum (18cm) what my Printer can do. All parts are easily printable, only on Hull, you should use support, from the basement. Single parts are glued together with normal CA (cyano acrylate) glue. It is easier to use activator on it. I will print also propeller and rudder to make it RC controlled, but I have to find some suitable drive for it. I will update this model with RC equipment I used. I used colours I have at home, but it looks good also with white deck and blakc cabin roof.
Edit: It works :D I used old RC equipment, it is powered by modified Microservo, reduced to cca 1000RPM (58/7 gearbox). Total weight 293g. I added some photos and video: https://www.youtube.com/watch?v=F0t73EoTn-k&feature=youtu.be
Boat propeller used is modified from this: https://www.thingiverse.com/thing:1667362
Support is recomended only few milimeters from the base and only on Hull part. The rest of the hull is ok with no supports.
Glue everything together with CA glue
I did this Tug in Tinkercad