MakeItFloat Boat-Rig

Hi Folk
i like challenges, so i decided to join the S.T.E.A.M. - MakeItFloat 
This is my first challenge thingiverse. So I started with my colleague to find a good mix of real solutions for transport of heavy Wight. We found something. This is the first concept or our total 3 ideas for this challenge. Hopefully we have enough time to generate, print and test all 3 concepts.
Focus on this Concept:

1. Print less parts and support structures as possible
2. Carry heavy load -> 2 Euro coins (diameter: 25,75 mm, thickness: 2,20 mm, weight: 8,50 g)
3. Priority: load > design
4. Must be moveable in real test

At first I decided to generate some boxes for the coins. 10 coins will fit into a red box at the moment. Boxes can be stacked together later.
I want to print this on a print area of 200x200x180mm with PLA.
Files, Instructions for assembly and print settings will come in the end.
End – 19.06.2015

Update
Update of concept
STL file prepared
Motor added (rubber band solution)
Now, I need to print and test :) 23.06.2015
Update
printed the main parts and test it. so the design is not the best :/. it swim but is not stable in the water. so i Need to modify the design. - 04.07.2015
Update
time is running. time is over. so i tryed but it doesn´t worked as i want. it Swim but not stable. so. it´s the end here.
THE END - 19.07.2015