MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
The full scale barges do not appear to be "interlocking" from what i could see, they looked like they were just stacked when in the "retracted" position and simply side by side in the "extended" position. since the full scale barges do not actually need to keep out ALL water they probably aren't watertight, but your seems like it needs to be watertight. My suggestion would be to make the sections with the "raised" sort of "rib" on the ends, that way you have a solid spot to apply a sealant like silicone caulking. if you fillet/chamfer the "ribbed" section at a shallow enough angle then you can print them upright so it sort of extrudes a "c" shape from the print bed.