On this blog, we often mention MarineDiesel engines as being suitable for repowering a variety of different vessels and applications. Indeed, perhaps 20% of our new engine orders are destined for repowering or retrofitting projects.
When should you decide that a repower if preferable to simply rebuilding the engine?
This is often not an easy decision to make. Most diesel engines can be rebuilt three or four times without any problems. It is important to note, however, that every time that an engine is rebuilt, no matter how competently, there will always be a degradation in engine performance. This should be a concern when deciding, “Should I rebuild?” or “Should I replace?”
Suppose your engine has never been rebuilt before. It has only been used in fresh water. It is still delivering an appropriate amount of horsepower, but starts sluggishly and you are needing to replace different components more often as they wear out. In this scenario, rebuilding the engine is probably a good bet. It is far less expensive than buying new, and it is just simply starting to near the point of requiring a complete overhaul.
In a different scenario, assume an engine has had extremely heavy use, always in salt water, and under a wide variety of throttle settings. The engine has had some hard wear. Symptoms start going beyond merely sluggish starting and may include smoke, noticeable decreases in power, and high increases in the number of spare parts required to keep it operating. The engine may have been rebuilt one or more times previously. This engine is a good candidate for replacement, and repowering.
Ultimately, the decision usually comes down to cost. Rebuilding an engine, on average, costs approximately 60% of the cost of buying new, assuming the use of OEM parts and keeping in mind the wide variation in labor costs around the world. Additionally, unless being replaced with the exact same engine make and model, new mounts, couplings, shafts, drives, and possibly propellers will also need replacement.
It is also important to note that engine technology has progressed at nearly light speed over the past two decades. In particular, emissions requirements have led to engines that are smaller, more powerful, and far more fuel efficient than even identical brands were twenty years ago.
Indeed, fuel efficiency should never be neglected in making this decision. Gains and operating cost reductions from more fuel efficient operation can easily cover the cost of repowering your vessel, as can the reduced maintenance that owners of new engines will experience.