Cat 3208
I offer the following information in answer to your questions.. My Bertram 1983 Flybridge Cruiser came from the factory with 260 HP Caterpillar diesel 3208s, with 260 HP each. In the late 90s she was repowered with Cummins 6Bs, 315 HP each. In my opinion these are a great powerplant for these boats. From what I have been told the gas powered 33s with 454 cu In 350 HP (aprox) are fine also. Your questions have been answered many times here as well as other sites, but to condense things I will say the following... Gas engines are cheaper to install, and cheaper to maintain. Diesels usually are more trouble free but parts are usually more expensive when you do need them. Gas is cheaper per gallon than diesel, but diesel B33s get about 1 nm per gallon on average while gassers use aprox. 1.3 gal per mile (running both engines at "average" speeds of from 10 to 20 knots}. I suspect that the final fuel cost/nm is less for diesels but here in NC it seems that in the final accounting diesels are somewhat cheaper to run (although lately it seems here that the per gallon cost for both gas and diesel change almost daily so exact fuel burn costs are difficult to pin down.. Diesels are considered by some as being "safer" than gassers due to the flammability factor of gasoline vs diesel, but while safety is sort of an individual concern considering the huge number of gas boats out on the water and the relatively few cases you hear about of gas boats catching fire this aspect of safety becomes a personal thing. In my case I felt that with 2 grandkids aboard safety was/is a major consideration. One other thing to consider if you are thinking about converting a gas boat to diesel is that, with diesel engines running fewer RPMs than gas (my Cummins engines are rated at 2,800 RPMs, and Yanmars usually are rated at about 3,800 RPMs, gas engines often have to operate at higher speeds (in the range of from 4,500 to 5,500 RPMs, although different models do have slightly different maximums), gas engines have to run at higher speeds to reach he same boat speeds as diesel, so the drive train of a gas boat will usually have to be changed to accomodate the lower speed higher torque of the new diesels. Shaft diameters, shaft seals, strut/cutless bearings and propellors all probably will need to be replaced/modified to meet the new diesel engine output characteristics. Finally, the cost to convert from gas to diesel is significant. You are much better off buying a diesel boat from the beginning than buying a gasser you plan to repower. In summary, IMHO, there is nothing wrong with a gas B33, there are some out there and as long as you maintain them and feed them ethanol free gas they can run fine. Diesels are more expensive to buy usually, and last longer but are more expensive to repair when needed, and are somewhat more efficient per gallon of fuel/gas used. As you probably have found, used diesel boats do cost more, but then they sell at higher prices when you decide to sell them. The safety factor of gasoline vs diesel flammability is for the purchaser to evaluate as a personal issue. I hope this post has been helpful. Do not fear, you are not alone in your questions of gas vs diesel. Most of us have asked this same questions at one time or another.
Frank B - IRGuy@aol.com "Phoenix" 1983 FBC Cummins 6Bs - 315HP Wilmington, NC