Those pits and craters eating away at your prop blades? That's cavitation damage. It's one of the most common—and most misunderstood—forms of propeller wear.
What Is Cavitation?
Cavitation occurs when water pressure around the prop blade drops low enough to form vapor bubbles. When those bubbles collapse against the blade surface, they create tiny but violent implosions that erode the metal over time.
How to Identify Cavitation Damage
- Pitting: Small craters or honeycomb patterns on the blade surface, usually near the leading edge
- Erosion: Material loss that makes the blade thinner or creates rough texture
- Location: Damage typically appears on the suction (back) side of the blade, near the tip or leading edge
Common Causes
- Incorrect pitch: A prop that's too aggressive for your engine creates excessive blade loading
- Running too shallow: Aerated water from surface proximity disrupts flow
- Damaged blade edges: Dings and nicks disrupt smooth water flow
- Engine over-propping: Lugging the engine at low RPM under high load
Prevention Tips
Choose the correct prop pitch for your application. Repair dings promptly before they worsen. Avoid running in excessively shallow or aerated water. Consider cupped blades for better bite and reduced ventilation.
When Repair Isn't Enough
Severe cavitation damage weakens the blade structure. If pitting extends through more than 20% of blade thickness, replacement is often safer and more cost-effective than repair.
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