the cummins 555s were truly bullet proof. I had a pair with 8000hrs and the ran well used no oil were hard to start when cold and parts were harder to come by. I traded them out for Yanmars now have 2500hrs on them and hope I will get 8000hrs out of them before i die. The yanmars use about the same amt of fuel at 20knots as the cummins did at 14. I am pushing my 42 convertible around love the boat. wide open will do 26knots. ron "undecided" out of edmonds wa > Date: Wed, 20 May 2009 10:20:31 -0700 > Subject: [UnifliteWorld] Re: A diesel engine perspective > From: [email protected] > To: [email protected] > > > Good discussion. I think there are trade offs with all the engine > choices and have not heard of a clear economic winner except for maybe > the smaller twin diesel trawlers which we all should have -except for > a desire for speed. Again it's all in what you value the most. > > When you consider the trade offs, I value safety and reliability.(no > gas fume worries and reliable starts). Also driving a boat is like > driving a loaded truck uphill. I have been told that diesels like > running hard so I don't feel like I am hurting anything when I go 2400 > rpm (18 knts) with a 20 ton boat full of fuel and water. > > If the fuel price gets too ridiculous I guess I'll sell the boat take > up golf. Diesel in Seattle used to be a big advantage because there is > no road tax (roughly 60 cents/gal) on diesel sold at the dock (love > that fishing lobby!). When I bought the boat I paid 60 cents a gallon > for fuel which was $1.20 on the road. Now the road tax savings makes > diesel just a bit less than gas. > > FYI I have the dreaded Cummins 555's for 12 years and, maybe I'm > lucky, but they have been bulletproof (knock on wood!) > > Never had a parts problem, but haven't needed many. I joined a site > called diesel.com which has been really helpful. > > I would probably look for another diesel, but would buy a gas boat if > the deal were right. > > Thanks for the discussion. > > > > On May 20, 9:04 am, Rocco <[email protected]> wrote: > > I have been spending a lot of time recently studying information about > > diesel engines, as we're considering buying a different boat. The > > size boats we are looking at are too large for gas engines and all > > have diesels. This has led me to do some comparison among different > > models and manufacturers of engines typically built in the 1980s. Let > > me say first, I am no mechanic and there are several people who > > contribute to this group who are, so I'm writing only as a consumer, > > not an expert. > > > > There's a lot to digest but the short story is this, two cycle engines > > are inefficient, smelly and leaky but reliable and easy to maintain > > and rebuild - EXCEPT Detroit V9 series. These engines represent early > > engineering efforts to increase horsepower and RPMs in diesels to make > > "go fast" boats. Unfortunately the result turned out to be short- > > lived engines. Rebuilds at 1500 hours are the norm. > > > > This decreased life holds true for four-cycle engines too. Many > > diesel people scoff at two-cycle engines and will explain the value of > > modern four-cycle diesels. However, when one begins to look into it, > > the true benefits are relatively recent and are based on problems > > encountered early in the designs, especially from the era of boosting > > HP. Even today, there are faults to be found. For example, fuel > > quality or cleanliness is critical in new four-cycle diesels as they > > tend to clog much more easily than older two-cycles. This is an > > important factor for anyone considering long-distance cruising and > > likely to encounter careless fuel facilities. > > > > What we see nowadays are four cycle engines being lightened > > considerably and run at almost twice the RPMs to acheived HP and > > speed. This equates to higher engine temperature with less metal to > > withstand it. > > > > What about fuel consumption? Well, that seems to be a hard one to pin > > down, mostly I suspect because diesel owners are reluctant to reveal > > the true facts. Apparently, it takes a certain amount of energy to > > push a boat through the water at a certain speed - no kidding! The > > higher the speed, the higher the fuel consumption. So, when diesel > > owners were talking about 10KT boats cruising at 1500 RPMs, the torque > > of a diesel was a significant advantage. However, pushing a diesel > > engine to 2500 RPMs to get 22KTS changes things significantly. > > Usually the number I hear for normal crusing with diesels is about 1NM/ > > 1GAL. > > > > Like everything else, each manufacturer has it champions and its > > detractors. (Note: Cummins 555 are engines to be avoided because > > they are not supported any longer and parts are difficult to obtain > > and expensive.) The rules for engine life - diesel or gas - remain > > the same: change the oil often and don't run them hot. Experts will > > say monitoring diesel exhaust temperature is the best way to protect > > an engine. > > > > The point of my comments is to suggest we might present a more > > positive attitude with respect to gas engines. There are lots of > > negative feelings out there towards gas engines that are, I think, > > unjustified. The long term reliability, initial cost, quiteness of > > operation, ease of repair, lower rebuild costs, etc. easily outweigh > > the added fuel costs for gas engines. In fact, the fuel cost > > differences are not as great as they used to be. > > > > Diesel or gas, the answwer I keep running into is: to save money, > > slow down. Still, I keep imagining us cruising on Sturdy Girl at > > 22KTS...aaah. > > > > That's my two cent's worth (and you get what you pay for). > > > > Rocco > >
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