I wanted to make a bigger boat so I just scaled up my boat http://www.thingiverse.com/thing:204303 to 200% and edit the bow.
It can be printed in two parts each 162 mm high.
Additional it has now a propeller drive and rudder control.
It is designed to use my Roxxy BL-Outrunner which I already used for my plane http://www.thingiverse.com/thing:86982
But this Motor is so powerfull that it would drive the boat to fast without controlling the speed. Currently I am waiting for a receiver to see if I can slow it down enough.
Meanwhile I found a little dc motor diameter 24 mm and added a mount to fasten it. Even though its less power it runs well enough and it should not go much faster without risk of capsizing.
The driving shaft is a 3 mm rod and the stern tube is 4/3 mm brass tubing.
For testing it I just bonded the two parts with tape ;-)
Be aware that you will use it at your own risk!
Better choose flat water without waves and where you can go in - in worst case... ;-)
The best is, if you print it with spiral vase methode. Then you will get a neat surface without any noses from layer change.
The hull is 3.0 mm thick.
I printed with layer hight: 0.3 mm and width: 0.6 mm.
Anyway, you have to print it hollow with one perimeter otherwise it will not fit inside the interface part to connect the bow to the aft.
I added a small base on aft to get more brim. I printed without heatbed and used 6 mm brim.
Printing the Aft
The stern is 1.2 mm thick. That means you must take four 0.3 mm solid layers on bottom to get a complete solid stern.
The top (the connection to the bow) shall not have solid layers to stay hollow.
Slice3r don't add solid layers on top, how many ever you enter. But I don't know how other slicers work.
Printing the bow
Here you shall not have solid layers, just a little brim.
And yes, be very careful, if you reach the nose.
Reduce the temperature and speed by and by in small steps.
The interface are supposed to put it fifty-fifty in the gap of each hull part. In this way the the hull parts are aligned and easy to glue.
Before gluing you should mask the edges of the hulls with tape to keep them clean from glue.
It was designed for the Roxxy BL-Outrunner http://www.robbe.de/roxxy-bl-outrunner-2834-08.html but it is more likely that it will be to strong.
Currently I used a dc motor that tolerates even a 4 cells battery.
It has a diameter of 24 mm and a shaft of 2 mm.
3 mm rod 130 mm long with 11 mm M3 thread on one end.
2 heat shrink tubes
One small one und a bigger one to put them one into each other, both about 45 mm long.
I fastened the smaller one with rubber band to the motor shaft before shrinking the bigger one upon it. It is not necessary on the other side because of the longer contact surface.