Curt, that is a good video. Many of the comments made were spot on. I do disagree with the 80% load all day long when talking about the Yanmar and Volvo 150 hp. That will increase longevity more at 30 to 40% load not decrease. The other issue I would have with the engine choice. I would not want to decrease power. Its to bad that Fluid Motion built the boat around a engine. They should have built a boat with power options like most do.
The Repower option should not even be being talked about. The oldest Ranger or Cutwater on the water is not even 20 years old. I just finished the Loop, a 6000 mile run. The highest percentage of new boats doing the Loop were Rangers and Cutwaters. Most of the boats had an average age of 20 to 30 years old. Cruising with originally installed engines. I cruised daly with a couple that had a 1989 38' Bayliner Motor Yacht with a pair of Hino's. Original engines 4500 hours. Not one issue all the way around. The key to longevity as I stated in the thread about timing belt replacement is maintenance, maintenance, maintenance!!! Maintain the engine on the conservative side. Not how many hours can I get out of an oil change, water pump, timing belt, belts, air cleaner, fuel filters...... The manual says X amount of hours or once a year. Marine age is as important as hours if not more important." I only put 30 hours on the engine this year should I change the oil? " Yes, Yes, Yes.
I believe If one of theses engines, Yanmar or Volvo in topic is propped correctly, operated at 30 to 40% load, all preventative maintenance kept up. The engine will last longer than you or the next two owners will own the boat. There are many small Diesel engines installed in 50 year old boats that are still running strong. There are also many that are on the third engine!! Manufacture tells you the maximum times for maintenance items.Either hours or marine age years. Those are maximum recommended. That doesn't mean you can not do it sooner. You just don't want to do it later. Manufactures give the engine's designed maximum RPM @ WOT. If you read the fine print in many manuals it will say if this recommendation is not met it may result in damage to the engine. The damage is not instantaneous it is damaging the longevity. Reducing engine hours of life operation. Poor condition of cooling system, restricted water flow (R27, R25, C26) all have this with the 1" thru hull. If you add any blockage in the cooling system that is already marginal you are not helping the engine to maintain longevity. Bottom line maintain the system ,flush it often. The antifreeze does two things in the aluminum block aluminum head engines. Acts as a coolant, and acts as a corrosion protector. The yellow anti freeze or extended life antifreeze has additives in it. Theses additives break down after a few years of use. The results is less protection from corrosion and could have sludge build up in the water jackets causing less heat transfer and uneven cooling in the block. The cure, change the antifreeze every two years and flush the block.
Don't worry about what engine you are going to replace the old one with. Worry about maintaining what you have. The BMW and Volvo automotive engines will be pushing your boat for many years to come if they are maintained properly. There is nothing wrong with exceeding the engine manufactures recommendations when it comes to maintenance.
