I would disagree that a bigger better maintained main engine is in any way preferable to a backup or get home engine. Sometimes things just can't be fixed (hence the term catastrophic failure). This applies to any mechanical device, no matter how careful you are. A catastrophic failure can happen for any reason, and it's usually at the worst possible time (Murphy). I'm not talking about bad fuel, stuck injectors, overheating or simple, fixable things, I mean looking in the bilge for your crankshaft, checking your rod caps through a new inspection port in the side of the engine, seized up solid can't move the flywheel with a 5 ft. bar sort of failure. One of my biggest concerns is the ability to maintain stearage and headway. I prefer twins but would not presume to suggest that it's the best thing ever. I require some sort of redundancy in propulsion on a boat, for my own peace of mind. I would think that a dedicated get home setup would cost almost as much and take up almost as much space as another identical main engine. Which by the way, could have been downsized to begin with had they been twins originally, and cheaper than a large main and small auxilary. It seems a better idea would be a genset with a big enough engine to act as a backup system, probably around a 20 kw. for the average 45 to 55 ft. trawler. Hydraulic drives would be easy to fabricate without the need for variable engine speed. A swash plate piston pump could be used to control shaft speed and manual valveing could be used for forward and reverse, all very simple, proven stuff, and relatively cheap. I'm thinking less than 4 g's for the whole thing. The problem with hydraulics is that once you start useing it you can't stop and will find all kinds of things to use it for. Hydraulic bow and stern thrusters can make the most hamfisted captain look like a hero at the fuel dock.

At 02:22 AM 1/12/05 +0000, you wrote: >I would disagree that a bigger better maintained main engine is in any way >preferable to a backup or get home engine. Sometimes things just can't be >fixed (hence the term catastrophic failure). This applies to any >mechanical device, no matter how careful you are. A catastrophic failure >can happen for any reason, and it's usually at the worst possible time >(Murphy). I'm not Twins are expensive, vulnerable, use more fuel, have extra drag. Get home wing engines suffer from some of the same issues. If you don't buy a reliable main and a lot of engines don't fit that bill, maintain it like your life depended upon it, maintain spares on board with tools to suit, then you need another engine. I run a lot of twins and the mentality of twin screw owners is: "what me worry". Mike Capt. Mike Maurice Tualatin(Portland), Oregon