A propeller strike rarely stops at the propeller. Discover Boating says a damaged propeller is likely unbalanced and can cause vibration, and that after a hard strike the shaft should be checked too.
How to inspect it
Discover Boating says to take the kill switch out, put the engine in neutral and turn the propeller by hand. Look for bent blades and nicks in the leading edge, and run your fingers along the edges for burrs. BoatTEST adds cracks, and notes that galvanically corroded bronze becomes brittle and prone to cracking.
On the sea trial, vibration that wasn't there before is the sign. A boat that's slow to move under throttle may have a spun hub.
Repair or replace
- Aluminium. Discover Boating says replacement may be more cost-effective, and BoatTEST that aluminium props usually aren't worth repairing.
- Stainless. Repair often makes economic sense, per Discover Boating. BoatTEST puts the repitch limit at usually 2 in.
- Bronze. BoatTEST calls replacement a last resort, and puts the repitch limit at 3 in for a propeller in as-new condition.
- Spun or damaged hub. BoatTEST says replacement is the best option. Discover Boating says a shop can usually replace a spun rubber hub.
BoatTEST warns against straightening a propeller yourself. A shop scans it and checks it for cracks with dye penetrant. Bends are straightened with heat.