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 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
