Thank you Tom, thank you very much.
What do you think about building one of your multichine, using wood for the gunwales (for the keel too as I suppose it also must be stiff) and pvc tubes for the 6 stringers?
The pvc tubes would be not stiff as aluminum or wood, but should be stiffer that a flexy inflatable. Plus, pvc tubes can be very easily sleeve jointed and are far cheaper than aluminum. I could even snap them this way http://victoriapatagonica.freeservers.com/91.jpg
So the assembly process wouldn't be totally a beast: hinges and pins will be needed to joint the wooden gunwales, keel, bow and stern. The rest of the boat would be easier to assemble.

What do you think about?