Seems like a good idea, probably works well enough. Got a couple of qualms though.
He says it gets 33% better fuel economy. Don't know about other countries, but diesel is usually 20-30% higher than gas here, so that's a wash. Not gonna pay for itself in it's lifetime.
I'm guessing that little engine is high pressure common rail. If you get any little bit of fuel contamination, it grenades the high pressure pump and distributes trash through the whole system. Injectors, rails, tank, pump, it all has to be gone through. Big money repair, it's an issue with all modern diesels.
I'm not real crazy about that belt drive either. Doesn't look easy to change, and a drive failure out at sea is a big problem.
The whole water-to-water cooling system seems pretty complicated too.