We have been using this down time, with Paul III and Cindy both convalescing from their injuries, to research engine selection. Among my other skills, I'm certified to teach classes in a very systematic and objective means of solving problems and making decisions. I've taken this opportunity to introduce Paul III to these skills, by performing a detailed, systematic, and objective decision analysis of which engine would be the best to install into the trimaran that he and I are building. The results surprised and amazed me, and perhaps a few of you might also find it interesting. We first listed all our objectives that we hoped to achieve in making this decision, and then we spent a great deal of time consolidating them into a list of eleven objectives. (That took a week.) Two of the objectives we classified as "MUST'S," which served as a quick up front go/no-go filter. The engines had to put out a minimum of 175 hp, rated at "Medium Intermittent," 3000 hours per year, 25 percent at full power. The second MUST was that it had to fit into the very narrow hull of the boat. Normally, in a decision like this, I would have a maximum permissible cost for the engine, but we chose to leave that one off. Of the nine WANT's that were left over, we selected the one that was more important to us than any of the others, and gave it a weight of ten. Our top objective was to minimize the probability of it being dead in the water off shore, and not being able to easily get it running again. (In the end, this one became the most difficult one to evaluate, and it was also the most subjective of all our objectives.) Other top objectives were that we wanted to have easy in frame maintenance and repairs, we wanted parts and service to be easily available, and we wanted to maximize the full intermittent power rating of the engine. All these got either an eight or a nine, in comparison to the one that we called a ten. Less important objectives all got a five or a six. They were to maximize mean time between overhauls, we wanted to minimize maintenance costs, and to minimize the weight of the engine. That is a quick summary of the objectives. In actual fact, we wrote long statements defining exactly what each one meant to us, and how we would evaluate each engine in its performance toward meeting the objectives. The MUST objective filters left us with five engines to consider: The John Deere 6068. I have no direct experience with this engine at all, but I've been impressed with what all the other fleet owners have to say about it. The one down side is that it has a week injection pump. Of all the engines, it is the easiest to maintain and repair in frame. It was a little light on the desired power, though. This is the only engine that I considered for which I have zero direct experience, and I left it in the group only because it gets such strong recommendations from people who I trust. The Cummins 6B5.9. I left this one in mostly out of respect for Captain Wil, who seemed to think it was the only engine I should consider. It gets high marks for being cheap and light, yet with a good record for reliability. Parts are most easily available at any NAPA store. This is a very common industrial engine, and we have many in our fleet, so I have a good idea as to what to expect from them. Before we did this decision analysis, I wanted to eliminate this one from consideration because it is basically a throw away engine with a solid block. I also saw this one as the second most easy engine among this group to repair and to maintain. It has the shortest life expectancy of all engines under consideration. The CAT 3208. I put this one into the group only because everyone else seems to consider it, and many select it for marine use. It is also a solid block throw away engine, but it has a history of lasting a very long time, and you can rebuild it at least a few times. It got the lowest marks for ease of maintenance, mostly because it barely fits in our hull, so we would have little room to work on it. Its V-8 configuration also was a bit more difficult to work on than the rest of them, which were all in-line engines. This one also got low marks on cost, because it was one of the more expensive engines under consideration. It also got low marks on weight, since it was a large engine. Of all the engines, it got the highest marks for power output, since it was a big engine, and it can be spun at high shaft speeds for rather impressive power levels. The CAT 3304. This is a very excellent industrial engine, very comparable to the John Deere 6068, though a bit smaller. I give all in-line CAT's very high marks for parts and labor availability, and fair marks for the cost of those two things. This engine put out the least power of all those under consideration here, and it is a heavy engine for the amount of power it does put out. I do like the low shaft speed of this engine, though. The CAT 3306. Everything that I said about the 3304 also applies to this engine, except it has two more cylinders. It's power to weight ratio is a bit more desirable, but still pretty bad. It is an expensive engine compared to others on this list, and it is by far the heaviest. Each WANT objective had a score, and each engine was scored as to how well it met each objective. The two numbers were multiplied together on each point for a weighted score, and then all the weighted scores were added up for a total score for each engine. The two engines that came out on top and only 0.6 percent apart from each other are the 6B5.9 and the 3306. That blew my mind away. This is like doing a decision analysis for buying a vehicle to drive to work, and then a Corvette ends up equal to a one ton four door pick up truck. On each objective where one performed well, the other did poorly. That worked to equal the two out against each other in the total score. The one engine that finished dead last was the 3208. The other two engines were close to each other, and about half way between the top and the bottom performers. I'm very certain that if we used someone else's objectives, then we would have a totally different result. Right now, I'm negotiating a price on an essentially new CAT 3306, with the complete marine package and an "E" rating. I'm very optimistic that I can get a very exceptionally good price, even though it will cause me to blow the budget that I've given to my son to build his boat. In my heart, that is the engine that I really want anyway; though this decision analysis has forced me to take an objective look at the engine I least wanted, the Cummins 6B5.9. If the deal on the CAT falls through, my intention is to pick up a junk yard Cummins engine and marinize it ourselves--probably with a keel cooler and a dry stack. That will cost a whole lot less than the 3306. This engine is even cheap enough that we can buy a spare to drop in if the other one ever goes down for maintenance at a bad time; and we used that rational as justification for increasing its score on some points of the decision process. The other advantage of this decision analysis is that it eliminated objectively the other engine that I was in love with, which was the John Deere 6068. If that engine put out more power, then it would have performed much better in this decision analysis, and we would probably be arranging to buy one. I really did not want to post this note, since it is rather technically boring and tedious. Several folks did ask how I intended to make this decision, though; so I decided to go ahead and post it. I hope that at least a few folks found it interesting enough to read this far. :-) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ :: Paul and Cindy Kruse :: KJV Joh 14:27 Peace I leave with you, 165 South Kenneth Court :: my peace I give unto you: Merritt Island, FL 32952 :: not as the world giveth, give I unto you. E-mail: plkruse@iu.net :: Let not your heart be troubled, 407-453-6206 :: neither let it be afraid. :: +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Paul Kruse wrote: > > > The John Deere 6068. I have no direct experience with this engine at all, > but I've been impressed with what all the other fleet owners have to say > about it. The one down side is that it has a week injection pump. Of all > the engines, it is the easiest to maintain and repair in frame. It was a > little light on the desired power, though. This is the only engine that I > considered for which I have zero direct experience, and I left it in the > group only because it gets such strong recommendations from people who I trust. > Alastair Bayne We had the 6068 DFM( nonturbo)135 hp in our Krogren 42, it was wonderful and very economical and the support I got from John Deere when we had a few problems as a result of incorrect instalation of hydraulics was equally impressive, and everything was resolved to my total satisfaction, and the time you need support is if things go wrong. We are taking our new (10) years old Trawler from a single cummins VT555 270 HP to twin John Deeres, 6068TFM 220 hp each, and we reviewed all the competition, who knows what the best answer is. The Caterpillar dealer in the Stuart Florida area did say when servicing our Northern Lights equipment, and I asked him for the advantages of the caterpillar, all he said was whem people become disillusioned with Caterpillar the generally go to John Deere, the reverse is probably also the same. We also got a very competitive deal on the engines, and if anyone is seriously interested email me direct and I may be able to point them in the direction of the right deal I also believe that Grand Banks preferred option is also now John Deere Alastair and Rosemary Bayne Moby Dick of Guernsey KK42 Nelsons Lady Lord Nelson 49 Victory Tug