Nothing wrong with either power choice IMO. 35 feet an under has more gas engines available than 35 foot and longer, that's just market reality.
Well, you posed and answered the question right there in the most sensible way I've seen yet here.
There
IS nothing wrong with gas as a marine powerplant
as long as you define what it's good for. Which is, as you say, smaller boats. Or cheaper boats or mass market boats. Gas engines are a really cheap way to power a boat, which means you can bring that boat to market for a whole lot less than you can a boat powered with diesels. The classic albeit overused example of this is Bayliner. The fact gas engines have relatively short lives compared to a diesel is fairly irrelevant for this market because the kinds of boats they're in don't get used all that much, relatively speaking. And if the boat is designed so the engines are under a cockpit where they can be easily swapped out, so much the better.
When you start talking about bigger, heavier boats, boats that represent a considerable investment and so will hopefully have a long life-- 30, 40, or more years---, or boats that are going to run long distances or short distances a whole lot of times for a whole lot of years, then diesels are the best choice, which is why that end of the market--- and the commercial market--- uses diesels virtually exclusively. They woudn't do this if it didn't make economic sense to the buyers and operators.
So both types of engines have their place. But what's being claimed by some here is that gas engines are an ideal powerplant for the upper half of the market. Which, despite their cheap initial cost and cheap replacement cost, does not hold true in my opinon. If it was, Grand Banks and Nordhavn and Fleming and the commercial lobsterboat guys and so on would all be using gas engines.
Engines, other than outboards, are not plug and play devices. Getting the engines in and out of a boat like ours, for example-- or a commercial fishboat---- is a major proposition. Doesn't matter how cheap the engine itself is, the effort to take the old ones out, put the new ones in, and then fix all the stuff you had to take apart or break to get the engines out and in is considerable and expensive. For a boat with an anticipated service life of 30, 40, 50 years or more, it makes no sense to have to undergo that process every few years depending on how much the boat is used.
It makes much more sense with a boat like ours to put one or two engines in the thing when it's built that have a good chance of lasting the life of the boat assuming proper operation and servicing. And the only way to accomplish that is by using a diesel. Which is why companies like American Diesel and Kong and Halverson and others started doing just that back in the 60s and early 70s.
The two different categories of boats are very much apples and oranges, and so need apples and oranges powerplants to make economic sense. Smaller, simpler boat, want to appeal to as large a recreational market as possible, wouldn't make sense to stick anything other than a cheap gas engine in it. Bigger boat, major investment, more complex design, needs to be really cost-effective in the case of a commercial application, it doesn't make sense to stick anything other than a diesel in it.
That's my take on it, anyway.
:lol:
