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 (ru