Essentially it's just a planter box made up of Pressure treated 6x6 landscape ties. The bottome would be made up of nylon screen, and plastic "chicken wire" type plastic fencing. The material is attached between the bottom tie, and the second tie do avoid it becoming detached under weight. The panel pictured is roughly 20" deep by 16'x10'. Not accurately represented by the 2 board stack, but I'm new to google sketch-up, and it irritates me.

The bottom sections could be coated in "duraliner" to make them waterproof instead of water resistant if need be. the screen material would keep the soil and fertalizer and such from being washed away. The plastic material would bear the weight, and keep it from failure under the load of the soil and plants.

The panels could be attached to eachother with lengths of rope or another such method that would allow for the natural drifting of the barges without damage to the panels. Sealed 55 gallon drums would easily float the panels. These are easily found, expecially in the region Rocketman is talking about.

This would free up barge space, keep some enemies of the plants at bay, provide a constant water source, prevent both over watering, and drought conditions. In addition it would provide another means fo travilling between the barges.

I'm not expert on the subject of growing, by any stretch of the imagination, but it's an idea I thought I'd put out there. The only problem I can foresee myself is: if nutrients would be lost to the open bottom of the panel. However I don't believe this would happen, as the panel would be submerged no more than 6-8 inches, allowing the rest of the soil to retain whatever was put into it that the plant hasn't used up.