INSIDER Marine Scene

A River Rat's Guide To Prop Repair

Dave Genz Shows How To Fix Damaged Props

by Steve Hoffman

Some of the best small rivers in the United States receive little fishing pressure. Anglers in most regions know of a shallow, rocky river or two that hold walleyes, but they also know that those rivers are hard on equipment--especially propellers. With aluminum props for small to midrange outboards costing $60 to $90, small-river anglers easily could spend an extra $200 per year for props.

Stainless steel props cost more than aluminum props, but they're also more durable. They're not recommended for use in shallow rivers, though, as the prop shaft rather than the prop blades absorbs the force of the impact. Stainless props also aren't available for smaller motors. Composite props are available from a few manufacturers, but again aren't recommended for small streams because the blades break easily and can't be repaired.

Propeller repair shops can fix most aluminum props, but may charge more than half the price of a new unit. Repairs may also take a week or more, which can be a problem when the fish are biting and fishing time is limited. If a repair shop can fix your damaged propeller, though, chances are that you can do the job yourself.

"Fixing a dinged prop is fairly easy," says Dave Genz, a guide on a particularly rocky, shallow stretch of the Mississippi River near St. Cloud, Minnesota. "Make a mold of a prop that's in good condition (the blades still are at their original pitch, or angle), then use that mold to reshape the prop after impact with an underwater obstruction."

MAKING THE MOLD
Begin by gathering the materials: a five-gallon bucket, a bag of concrete mix, and a propeller. "Make sure the inside of the bucket is clean and dry or the concrete won't stick," Genz says. "Also be sure to buy masonry concrete. The coarser stuff, often used to patch driveways, contains small rocks that may damage the prop."

Follow the manufacturer's instructions for mixing the concrete, then pour the wet mix into the bucket until it's about one-third full. "Let the mix set for a few minutes, then push the prop into the concrete in the center of the bucket," Genz says. "Make sure the front of the prop (the side that faces the boat when it's installed on the motor) faces down."

Another handyman-boater who makes his own molds recommends covering the hub with tape to prevent concrete from drying in the hole. Genz warns, however, "Don't immerse the whole unit in concrete, just push it down far enough to capture the shape of the blades."

Consult the concrete manufacturer's directions once again for recommended drying times and be sure to remove the prop before the concrete is fully set (hardened). If the prop is left in the mold too long, it's possible that it will become stuck in the cement (as one unlucky reader found out -- the hard way (photo). "One the prop is removed the mold is ready for use, but removing the portion of the bucket above the concrete with a saw or torch makes the mold easier to use," Genz says.

USING THE MOLD
When the prop strikes an obstruction hard enough to bend a blade, grab your mold along with a steel file and a rubber mallet. Remove the damaged prop from the motor and inspect the blades. Aluminum blades usually fold over when they hit large obstructions like boulders and logs, but an impact with a sharp edge may produce a small cut. Use the file to remove sharp edges before putting the prop in the mold.

"If you don't file down the sharp edges they will dig into the concrete when you pound on the prop with the mallet," Genz says. "You might still be able to return the blades to their original pitch the first few times you use the mold, but the original shape eventually will be lost. With proper care, a concrete mold probably will last longer than your outboard."

After the burrs have been removed, place the prop in the mold. If the blades are severely bent, the prop won't sit flush in the mold. "That's OK," Genz says, "just line up the prop as much as possible. Then hit the outer edges of the blades sharply with the mallet until they begin to take the shape of the mold. Hit each blade a time or two before moving to the next. Continue this process until the prop fits tightly into the mold."

Some prop shops weld pieces of aluminum to the blades to replace pieces lost during an impact, but again, Genz doesn't think that's necessary. "Those chunks of metal usually pop out as soon as the prop hits another obstruction. Props with missing metal may not perform so well as new props, but most river anglers aren't interested in high-performance boating. They just want to get to the fish."

1. File burrs on the blades.	2. Strike the blades with a rubber mallet.	3. Replace the prop and resume fishing.