When... first Fuel Cell Yacht...

One of the biggest advantages of fuel cells are their small size and variable output. One of the biggest drawbacks is low thermal efficiency. On most boats thermal efficiency counts for a lot more than weight efficiency, especially for things that are situated down low in mechanical rooms. Even the variable output is probably better handled by a computer balanced battery bank, and running generators near full load for brief periods of time to recharge the batteries. The first place we are likely to see fuel cells are on high end racing sailboats, I doubt that we will see them on cruisers, liveaboards, or luxury yachts anytime soon.

Plastimo were selling the Max Power range of fuel cell gen-sets. They were getting popular around parts of Europe, not sure how they are doing today. A neat little unit too.

http://www.avanteyachts.com/joomla/index.php/tech-topmenu-40/fuel-cell-technology-topmenu-49

Other than on commercial ships in the "liner trades" I don't think I have ever heard a single owner, engineer, designer, or anyone associated with yachts mention the term or concept of thermal efficiency. It might be a random topic of internet discussions but the brand of spring water and performance of AV/IT gear is light years ahead of efficiency of any kind on most boats where it would make the least bit of difference.

What counts is price, volume, and reliability ... and not necessarily in that order.

Really? I hear people talking about fuel efficiency fairly regularly, and range. Mostly in production boats, which are most of the market. There haven't been any major advances in marine propulsion in terms of efficiency of the engine in quite some time. Pretty much everyone is near the limits of efficiency most of the time. If you cut that efficiency by 30% people would probably start to talk about it.