One of my sons is considering buying a power boat and has seen LPG powered unit, is this a sensible option, I would recomend diesel but he is thinking LPG , boat would be on South Coast, what is LPG availability.
However - an LPG Boat will be thousands cheaper, and actually very cheap to run (at least half the cost of petrol at last check)
The range won't be great just due to the limit of fuel you can carry - but I ran an LPG boat for 3 years, got the cost of the conversion back in one season and had no problems once the teething ones were solved.