Energy efficiency on board
As with any project, there are many aspects that are important to make the whole project successful. Building a boat that can be powered solely by renewably generated energy is no different. Everything has to work together to make sure the boat can sail for as long as desired while being comfortable and save at the same time. Unfortunately many of these aspects are conflicting.
For example, it would be most efficient to create a very light boat. But this means that you have to remove as much as possible. But to make a boat comfortable and safe, you want to add things like a fridge, toilet and rescue equipment. As this will add a lot of weight to the boat, more energy is needed to sail for the same time.