How do I choose the right shaft length for my trolling motor?

Choosing the correct shaft length is important so that the angler's electric motor does not cavitate, creating fish-spooking noise. The rule of thumb is that the top of the motor section should be submerged 12". In general, shaft length selection is more critical with bow-mount motors versus transom-mount motors. Most boat transoms are similar in their distance to the water, and Minn Kota’s standard transom shaft lengths should be adequate. With bow-mounted motors, there is much greater variation in shaft length requirements. Measure down from the mounting surface of the transom or bow to the water level. Add 5" to waterline measurement for fishing in rough water. Add 12" to waterline measurement for steering a hand control motor while standing. Use this measurement and the tables below to find the appropriate shaft length.

Transom Guide

Transom to WaterlineRecommended Shaft Length
 0"-10" 30"
 10"-16" 36"
 16"-20" 42"
 Over 22" Consult Factory

Bow Guide 

Bow to WaterlineRecommended Shaft Length
 0"-10" 36"
16"-22" 42"
 34"-44" 72"

Engine Mount Guide

  • Minimum clearance required from spine of outoard to end of cavitation plate (see diagram below).
  • Cavitation plate to waterline 13" (minimum).

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