How to Measure Outboard Shaft Length

Proper outboard shaft measurement ensures correct propeller fit and optimal performance. Measure from the lower unit's mounting flange to the tip of the shaft.

Essential Measurement Steps

  • Locate the lower unit mounting flange on the engine
  • Measure straight down to the shaft tip using a tape measure
  • Include any threaded sections in your measurement
  • Verify against manufacturer specifications

Measurement Methods Comparison

Method Cost Time Accuracy
Manual Tape Measure $0 5 minutes High
Shaft Gauge Tool $25-50 2 minutes Very High
Professional Measurement $50-100 10 minutes Excellent

Common Measurement Mistakes

  1. Not measuring to the actual shaft tip
  2. Ignoring threaded portions of the shaft
  3. Failing to account for trim adjustments
  4. Measuring at an angle instead of straight down

Why Proper Measurement Matters

Incorrect shaft length causes cavitation, reduced performance, and potential damage to the outboard motor. Always verify measurements before purchasing replacement parts or making modifications.