COMPOSITE MATERIALS, combinations of resins, plastics and space-age fibers, are replacing metal in everything from bicycle frames to car engines. Now composite construction has entered the mainstream marine world in the form of the COMPROP, a composite propeller.
     The COMPROP was introduced several years ago as a three-blade design intended as an inexpensive "get-home" spare wheel. Now the COMPROP has been redesigned as a primary-use, four-blade propeller, and it will be offered by Regal, Wellcraft and Corona as the original-equipment propeller on a limited number of new boats.
     One such boat is the Regal 202SE. To see how the COMPROP stacks up against the aluminum alternative offered by Regal on this boat, we headed to the boat-builder's test center in Orlando.
     The COMPROP can handle up to 200hp (outboard or stern drive) aboard boats as big as 21' and/or 3,000 pounds. Our 19'10" bowrider test boat, with its 180-hp MerCruiser 4.3LX V-6 engine and an Alpha One outdrive, fit those parameters easily.
     COMPROP has a 13 1/2" diameter, and it's offered with 18", 20" and 22" pitch. Composite Marine Propellers, which manufactures the COMPROP, says changing from three blades to four smaller blades spreads the load out over more area, eliminating the excessive blade flexing that hampered the performance of earlier models. CMP says the COMPROP blades now flex about as much as an aluminum prop's blades.
     CMP refuses to divulge the exact material used in the prop, other than to say it's a composite—let's call it Unobtainium.
     It's very light—the 22" model weighs just 2.5 pounds, compared to 4 pounds for an equivalent aluminum prop. The entire prop is one piece, with splines for the prop shaft molded into the hub. There's no rubber hub cushion.
     The alternative offered by Regal on this boat is that long-time favorite, a three-blade Quicksilver aluminum prop with a machined spline insert and a rubber hub.
     In our test, the aluminum propeller showed the strongest midrange speeds while the COMPROP provided the quickest acceleration—as would be expected of a four-blade prop—and top speed (see chart).
     But what about the COMPROP's durability? CMP claims the COMPROP stands up well in general use. In a high-speed, solid impact, the COMPROP blades are designed to break off the hub, thus protecting the shafts and gears of the drive unit.
     This is why the COMPROP doesn't have a rubber hub center. CMP's point is that it's better to break an inexpensive prop than an expensive gearcase.
     In the same circumstances, aluminum blades would likely bend, absorbing some shock, while the rubber hub would (you hope) handle the rest.
     If bent, the aluminum prop could perhaps be repaired, not necessarily replaced. And unless it is severely damaged, the aluminum prop remains a propulsion device.
     According to Quicksilver marketing manager Bill Gius, "Our rubber hub and the ductility of the metal material will protect the gearcase. It's still more economical to repair an aluminum prop than to continually replace a composite prop."
     The cost (or even possibility) of repairs, of course, is determined by the extent of the damage to the propeller.
     Perhaps the COMPROP's strongest feature is its price. The 22"-pitch COMPROP lists for $94.95, compared to $140.75 for the Quicksilver aluminum prop.
     The COMPROP is available with hub splines to fit MerCruiser and OMC Cobra stern drives and all brands of outboards.
     It also can be ordered from marine dealers and through catalog houses like Overton', Bass Pro Shops and West Marine. Outboard Marine Corp. sells it under the Prop-Tech label through its OMC Parts and Accessories division.
     The original three-blade COMPROP also is available in several sizes for smaller outboards.
     It's the COMPROP's low price that has attracted the attention of boat-builders. But performance can't suffer to save a buck, and Regal is certain its customers will be happy with the COMPROP.
     Clearly, space-age materials are coming of age.

For more information, contact: Composite Marine Propellers, Dept. B, 9808 Pflumm Rd., Lenexa, KS 66215-1208, Bass Pro Shops, Dept. B, 1935 S. Campbell, Springfield, MO 65898, 800/227-7776;  913/492-7767; OMC Parts & Accessories, Dept. B, 200 Sea Horse Dr., Waukegan, IL 60085, 708/689-6200; Overton's, Dept. B, Box 8228, Greenville, NC 27835, 800/334-6541; Quicksilver, Dept. B, Box 1939, Fond Du Lac, WI 54935, 414/929-5000; Regal Marine, Dept. B, 2300 Jetport Dr., Orlando, FL 32809, 407/851-4360; West Marine, Dept. B, Box 50050, Watsonville, CA 95077, 800/538-0775.