I realize this is for your boat and that's great, but here's my take on desalination in general. As a retired engineer once involved in the water/wastewater industry, I can say that "desal" has always suffered from high energy requirements, especially since we in North America have been conditioned to use cheap surface or groundwater, relatively pure with small energy cost. As one former client said "it would be a lot cheaper to purify wastewater than ocean water". Meanwhile ag uses up to 85% of all potable water. Look for ag to water "economize" in the future (basically go the route of veggies and fruits) while using some secondary water sources ("reclaimed" wastewater). Desal would be great if massive solar distillation methods could be perfected.