Re: hull extension in progress with picks
Re: hull extension in progress with picks
Hey Oops,
I'd like to add my $0.02 worth to some diesel engine items being discussed...
This comes from having owned a 6.2L diesel for years, and from being in the alternators industry.
The explosion potential is not there for a diesel as in a gas engine, so while I don't know for smaller boats (sorry but your beautiful Sea Ray is still a smaller boat when it comes to diesels), I do know that for larger boats (ie boats running a Cummins ISL or ISM engines) they do not use marine alternators, they use standard heavy duty (meaning automotive/industrial) alternators, with no special explosion protection.
Diesel fuel does not burn like gasoline. You can basically drop a match into diesel and it will extinguish the match (personal experimet with leftgover fuel from fuel filter change, of course done under tightly controlled conditions on my driveway under supervision of an adult). You put a rag (wick) in the fuel, and it will burn like an oil lamp, because that is what you then have.
An additional plus for you (slow cruising with Mrs Oops) is that diesels are especially stingy at low speeds because they run extremely lean, and they don't waste a lot of energy sucking air through an almost closed throttle. I wired a switch to allow our truck to idle without the key when we ran errands (keep the truck nice a warm in the winter), I'm not sure how much fuel was used during these periods of idling, but I never noticed it in mileage difference. We sold the truck with nearly 200,000 miles and it ran like it was new - 6.2L is usually good for 200-300,000+ miles with care. Adding a turbo to the 6.2L brings HP to low/mid 200's, with mid-range torque like a big block, with which it is similar in weight. Only issue is the 6.2L/6.5L is an older indirect injection diesel, and they are much noisier than a gas engine. On the good side, the diesel clatter is mostly high frequency noise that should be able to be controlled by insulation in engine compartment.
The Duramax may be heavier, but they are quiet, almost as quiet as a gas engine. They are also much more powerful. Durability is as good as the 6.2/6.5L engines. The duramax is essentially an Isuzu engine, and they have been making good diesels for a long time, and know what they are doing. Keep in mind that the Duramax is used in medium-duty trucks, not just in pick-ups. The Cummins engine is an excellent one, but it is heavier than the Duramax, and noisier, but it would likely last the life of the boat.
As far as drive ratio, you would have to keep it low since diesels max RPM is much lower than gas engines. 6.2/6.5L max is (I think) in the 3400 RPM, the Cummins 6 cyl is (also I think) in the 2800-3000 RPM range, but both types have so much torque that they would spin the prop just fine with a lower drive ratio.
Diesel would seem to have some advantages with your intended use, and a few disadvantages - as you've said, boats are all about compromises (or somethign like that).
Take care - I hope you get the shop settled soon (if not already).
JorgeE