On Bay Pelican, a Krogen 42 single engine trawler, I have installed a Yanmar 27 hp get home with its own shaft and max prop. This wing engine is off center to starboard. It serves three purposes: 1 Gives me greater maneuvering ability in close quarters. I turn the wing engine on every time I enter a marina, mooring field or attempt to dock. The main engine pulls to starboard in reverse and the wing engine pulls to port, so its assistance is substantial. I can actually dock on a wall to starboard and pull off backward to port. This is the most useful feature of having wing engine. 2 With the addition of a large alternator, the wing engine serves as a backup to my generator. Although not as quite as the generator it is much quieter than the main engine, much more fuel efficient and can charge the batteries fairly rapidly. In ten years however, I have never needed to use the wing engine for this purpose, other than testing. 3 The wing engine serves as a backup to the main engine. In calm water it moves a Krogen 42 at 4 1/2 kts. Again in 10 years I have never needed this backup, with the exception of one time when docking when I killed the main and needed an immediate reverse. Can't say whether the cost is justified for a get home engine. After 10 years with a single engine boat, I appreciate both the fuel efficiency and the ease of maintenance. The wing engine although a second engine is not used under way and requires little maintenance, usually only once a year. Marty Campanella Bay Pelican KK42