Your Outboard Motor
If you’ve dinged a propeller really badly lately, you know that a replacement prop can put an even worse ding in your wallet. A new aluminum prop can cost $200, and stainless-steel wheels start at $350. But now there’s a third alternative. The COMPROP is a composite propeller (please don’t call it plastic) that will equal or better the performance of a good aluminum prop for less than $100. Available for most brands of outboards and stern drives up to 200 hp, the COMPROP is now installed at the factory by some boat manufacturers, including Wellcraft, Regal, and Glastron.
Molded of a proprietary fiber-filled resin material, the COMPROP has a splined aluminum hub insert to mate with the propshaft. Unlike aluminum and steel props, COMPROPs do not have a rubber-cushioned hub to protect the gearcase from prop impacts–the company says its blades will flex to absorb minor impacts or simply break off in a hard impact. The theory is, it’s much less expensive to replace a COMPROP than risk damage to the expensive gearcase or to repair a metal prop.
We had the opportunity to test the COMPROP on Alaska’s Kenai Peninsula. The rough Anchor River beach launch we use to reach halibut on Cook Inlet often requires running through rocks and gravel to return to the landing.
Our test boat was a heavily loaded 19 1/2-foot Almar Lite aluminum boat, powered by a 1983 Evinrude 115 outboard and running a 13- by 19-inch OMC SST II stainless-steel prop. We started by measuring the boat’s performance with the old prop (see chart). We then gathered the same speed and acceleration data with a new OMC SST II, an OMC aluminum prop, and a COMPROP, all 13 by 19 inches. The COMPROP met its claims, producing about the same top speed, and better acceleration, than the aluminum prop. It was only 0.8 mph slower than the new SST II, and almost 3 mph faster than the battered original prop—proof that it pays to run a straight prop.
Note that the COMPROP is a four-blade design, so thrust is spread over the two drive blades that are always in the water. This elminates the problem of the composite blades flexing under load, not a concern with aluminum or stainless props at this performance level. And after the performance test, we ran the COMPROP through a gravelly area along shore, succeeding only in slightly chipping the blade edges.
We left the COMPROP with the boat’s owner for the season, hoping to get some long-term time on it, but when push came to shove, he stuck with the stainless prop. He reasoned that if he were running up the Ukon River, say, and the COMPROP sheared its blades, he’d be up the proverbial creek for real. Losing the blades completely is the COMPROP’s one serious weakness. Even a badly bent metal prop will likely produce some thrust, but when the COMPROP’s blades go, so does your control.
The COMPROP we used had a suggested retail price of $89.95, compared to $110.95 for the OMC aluminum prop and $355.95 for the OMC SST II. Johnson and Evinrude dealers can order a COMPROP directly from OMC Parts and Accessories. As an alternative to aluminum and stainless props COMPROP is worth consideration by boaters who don’t demand the ultimate performance and don’t operate in unusually rugged conditions. For more information contact Composite Marine Propellers Inc., 240 Scottsville Blvd, Jackson Ca 95642. Contact Cathy.