Hi, my name is Naroa, I don’t know much about boats. I’m doing an investigation on the length of time a 115Hp motor should be going. We have a fleet of boats that coast guard a manmade lake that supplies water to the Panama Canal. We have 3 shifts a day which means that the boats have their motor running for 8 hours. I need to know what you consider the life expectancy of these boats to be? PS Your answer is VERY IMPORTANT.
Hi Naroa: I’d be happy to try and answer your question–but first I need a bit of information.
1-What sort of engine, gas or diesel? 2-Which make and model? 3-What percentage of time at idle and how much time under load does the engine spend?
A well maintained diesel—which means change the oil at regular intervals—in commercial service—is typically good for between 10,000 and 15,000 hours of operation. On a sailing yacht, where the engines tend to spend a lot of time unloaded and not have regular maintenance, this figure usually ends up more like 7500 hours.
Taking a guess, if this were a four-cylinder Yanmar, and your Coast Guards spent 1/3rd of their time at fast idle underway, 1/3 at half power and the rest at full continuous power, and if you changed the oil every few hundred hours, I would say you should be able to get 12,000 to 15,000 hours between major overhauls.
Note: Making sure that the engine and prop are correctly matched, i.e. that the engine can reach its maximum rated rpm underway, is a critical factor in your type of application.
I’ll try and get you more specific data if you can answer the questions. Regards–Steve Dashew
PS: We came through the canal on our sailboat, BEOWULF, last February (2000/my third trip). Steve Dashew
Posted by Steve Dashew (November 30, 1999)
