How to Choose the Right Shaft Length for Your Trolling Motor

One of the most common mistakes anglers make when buying a trolling motor is getting the shaft length wrong. Too short and your prop cavitates out of the water in choppy conditions. Too long and you're dragging unnecessary weight and risking damage. Getting it right makes a real difference in performance and control.

Here's exactly how to choose the correct shaft length for your boat.

How to Measure for the Right Shaft Length

Start by measuring the distance from the mounting surface (the top of your bow) down to the waterline. Then add 20 inches. That's your minimum recommended shaft length.

Example: If your bow is 18" above the waterline, you need at least a 38" shaft — so a 45" shaft would be your starting point.

For rough water or high-speed fishing, add another 5–10 inches of buffer to keep the prop submerged when the bow rises.

Shaft Length by Boat Type

Jon Boats & Small Aluminum Boats (under 16 ft)

These sit low to the water with minimal bow height. A 36"–45" shaft is typically sufficient.

Bass Boats (16–21 ft)

Bass boats have a moderate bow height and are often fished in variable conditions. A 45"–60" shaft is the most common range, with 52" being a popular sweet spot.

Pontoon Boats

Pontoons sit higher off the water than most people expect. A 60"–72" shaft is usually required, sometimes longer depending on the model.

Walleye & Multi-Species Boats (18–22 ft)

These boats often run in rougher water. A 52"–72" shaft gives you the depth needed to stay submerged in chop.

Large Bass & Tournament Boats (21 ft+)

High-performance tournament boats have elevated bows and are pushed hard in rough conditions. A 72"–90" shaft is recommended.

Offshore & Large Center Consoles

These boats have significant bow height and are used in open water with real wave action. A 90"–120" shaft is required — this is where the Rhodan Gen5 (up to 120") and Garmin Force Kraken (up to 110") shine.

Kayaks

Kayaks sit extremely low to the water. The Garmin Force Current is purpose-built for kayaks with a compact, adjustable design that works in tight spaces.

Shaft Length Options by Brand

Here's what we carry at Captain Mason Yacht Services:

• Garmin Force Kraken — 48", 63", 75", 90", 110" shafts
• Garmin Force Current (Kayak) — Compact adjustable design
• Minn Kota Ulterra Quest — 45", 60", 72" shafts
• Power-Pole MOVE PV — 36", 45", 52", 60", 72", 84", 96", 110" shafts
• Power-Pole MOVE ZR — 45", 52", 60" shafts
• Rhodan Gen5 — 108", 120" shafts

Common Mistakes to Avoid

• Going too short — The most common mistake. When in doubt, go longer. A prop that breaks the surface loses all thrust instantly.
• Not accounting for rough water — Calm lake measurements don't account for bow rise in chop. Add buffer if you fish open water.
• Ignoring motor mount height — Some aftermarket motor mounts raise the mounting surface, which effectively shortens your shaft. Measure from the actual mount, not the deck.

The Bottom Line

Shaft length is one of the most important — and most overlooked — specs when buying a trolling motor. Measure your bow height, add 20", and factor in your typical water conditions. When in doubt, size up.

Browse our full lineup by brand to find the right shaft length for your boat:

Shop Garmin Force Trolling Motors →
Shop Minn Kota Trolling Motors →
Shop Power-Pole MOVE Trolling Motors →
Shop Rhodan Trolling Motors →