Repowering Your Boat:By Michael Vatalaro
What You Need To Know
Published: April/May 2013
There are many considerations when starting a repower project, including some that are unrelated to the performance requirements of your boat, such as having a local dealer or mechanic nearby for servicing that you like and trust. The following should give you a good starting point from which to plan your shopping list.
Transom Limitations: Space & Weight
The physical limitations of your transom will dictate how much horsepower and weight you can put back there. While modern four-strokes are getting close to their two-stroke counterparts in weight, they still will add to the load at the stern. If you were not running the maximum-rated horsepower in your previous set up, you may have some wiggle room, and be able to absorb some extra weight without impacting seaworthiness. It's a good idea to check with your boat builder what the design limitations were before you start shopping. Weight considerations could limit you to DI two-stroke technology.
Space is more of an issue if you are running twins (or more) because some of the high-horsepower modern four-strokes need more width between the engines, but not always. Honda, for example, designed their four-strokes to fit the standard footprint for easy repowers.
In addition, with the increased horsepower ratings available today, you may wish to switch from twins to a single outboard configuration. For example, swapping twin-150s for a single 300-hp motor, in theory, will reduce both weight and drag, which should increase fuel economy without sacrificing performance. However, boatbuilders caution that the increased power and torque of these modern, power-dense outboards can be too much for transoms that weren't designed for it. A safe bet is to limit horsepower to the highest horsepower single engine configuration offered as original equipment. The boatbuilder should be able to go into greater detail.
Stop and trust your senses. They've got some important news for you
Here's what's new, and what's hot in electronics from the 2014 Miami International Boat Show
What you should know about this often overlooked marine system