Why are diesels okay for cars but not boats?
This is a guess: My understanding is that most carbon collects when the engine runs relatively cool. Short idle periods do not let the engine cool down very much, so frequent idling is not a problem, but extended idling is. One diesel efficiency is that at idle and low loads, the diesel can run with mostly air and a tiny amount of fuel injected just to keep things running. In contrast, a conventional gasoline engine must draw a cylinder full of fuel/air and if the mixture is too lean it will not ignite. So there is a “floor” below which the gasoline engine just burns too much fuel. As a result, the diesel runs cooler at idle. Diesel and gasoline engines also produce different wastes. The diesel exhaust is much higher in particulates. The particulates are large enough that a relatively simple water (or, I believe, centrifugal) trap is moderately effective at reducing emissions — even though water traps are relatively poor at collecting small particles (gases go through the water in bub
