The Wheel Deal
The right set of propellers can smooth the ride and increase efficiency.
Cruising in your boat is a pleasant experience. If you could make it more enjoyable while spending less money than you might expect—and throw in some fuel savings while you’re at it—it would be a no-brainer, right? Then you should consider upgrading your propellers.
Whether you’re buying a new boat, one that’s new to you, or just looking for ways to upgrade your current pride and joy, going with a new or reworked set of propellers is one of the best ways to get rid of vibration and improve fuel economy.
The latest trend in propellers is toward increased numbers of blades to improve midrange efficiency and to reduce engine- and shaft-related vibration and noise.
“A four-blade is going to give you the most efficiency, but a five-blade is going to be smoother,” says Greg Platzer, president of Platzer Marine Propulsion in Fort Lauderdale, which does custom and semicustom propellers.
Today, propeller makers fabricate custom wheels just as frequently for owners of “regular boats” as they do for custom builds and megayachts. “Day in and day out we do a lot of customs,” says Kevin Mitchell, naval architect at Michigan Wheel Marine. “In the 50-foot to 60-foot range, where the boats are sophisticated enough and expensive enough, people want to optimize the whole propulsion system.”
For example, Michigan’s EQY Series is a more sophisticated design than a traditional Dyna-Quad to begin with, but the company can take a pair of EQY wheels and further match them to a given boat through fine-tuning to optimize efficiency.
EQYs cost a little more than off-the-shelf props but the results could be worth it. Platzer estimates they’re 20 percent more expensive than semi-custom props and 40 percent higher than a two-of-a-kind pair designed specifically for your boat. Michigan Wheel’s Mitchell says a semicustom set could cost as little as five percent more if he is customizing props that are already close to optimum for a given application, but a full-on custom pair could cost 50 percent more depending on the tooling costs.
Of course, you need to determine if you’re going to keep your boat long enough for the investment in new props to pay off in savings due to improved fuel economy. The numbers vary from boat to boat. “Time and time again we’ve gone through this analysis, and if you increase efficiency by two to five percent, you look at the economies to see if it’s worth it,” says Mitchell.
If you don’t want to buy new wheels, the other option is to have your current props custom-tuned for maximum efficiency. The best-known systems for doing this are the Hale Measurement Recording Instrument (better known as MRI) or Prop Scan Enhanced Propeller Scanner (EPS). The MRI propeller-recording system and equipment are available through Michigan Wheel, while Prop Scan comes from Propeller Dynamics in Australia. Both systems use a computer program to read propellers’ specifics and then custom-match the wheels to improve efficiency and eliminate vibration. These processes are typically most effective on propellers that were built by hand. If your propellers were designed and built with computer numerical-control processes—well, computers do a pretty good job of getting things right the first time.
In the end, whether you decide to spend the money on a new pair of props or have your wheels tuned up by computer, the investment could be worthwhile. “A general principle is that for all these boats, it’s worth it to go through the process to determine if the propulsion system is reasonably optimal,” advises Michigan Wheel’s Mitchell. At the very least, it will make your cruising more pleasant.
Michigan Wheel Marine
Platzer Marine Propulsion
Prop Scan USA
This article originally appeared in the April 2012 issue of Power & Motoryacht magazine.