I found this USV project on Hackaday the other day and the project leader was kind enough to make the 3D files available for download. https://hackaday.io/project/25508-n3m0-the-autonomous-boat
I'm in the process of printing up my own hull and fitting it out with a Pixhawk 2.1 and 2x BlueRobotics thrusters. I think it will come out to be around 1m in length when complete, which is a much more mangeable size than my larger red USV. What I like this the top hatch to seal in all the electronics and I won't have to use Pelican cases.
I'm thinking about making up two hulls so I can start playing with multi-vehicle options and maybe get some swarming actions going. It makes for a good size for the temperature sensor, a camera, and maybe a small single beam sonar.
It prints ok so far. I've had some delamination of the layers, probably due to the cooler room temperature and me not having an enclosure for the printer. Some filling and sanding of the gaps will be needed once everything is glued together.