Shaft Length Explained: Choosing the Right Fit for Your Transom
One of the most common mistakes when buying a new outboard motor is selecting the wrong shaft length. If the shaft is too short, the propeller will ventilate (sucking air) and lose grip. If it is too long, it creates unnecessary drag and can affect the boat’s handling. At Wave Engines, we want to ensure you get the perfect fit the first time.
Measurement should be taken vertically from the top of the transom to the bottom of the hull.
Industry Standards: 15″, 20″, and 25″
Marine manufacturers have standardized shaft lengths to match boat designs. When you browse our online store, you will see motors categorized by these measurements:
| Standard Category | Actual Height (Approx) | Common Boat Types |
|---|---|---|
| Short Shaft | 15 Inches (38cm) | Small Tinnies, Inflatables |
| Long Shaft | 20 Inches (51cm) | Runabouts, Center Consoles |
| Extra Long | 25 Inches (63cm) | Offshore Fishing Boats |
How to Measure Your Boat
To determine what you need, follow these steps or consult our Frequently Asked Questions:
- Ensure the boat is level on its trailer.
- Place a tape measure at the very top edge of the transom (in the center).
- Measure straight down to the “V” or the lowest point of the hull (the keel).
- If your measurement is close to 15″, you need a Short Shaft. If it’s near 20″, you need a Long Shaft.
Expert Assistance in South Melbourne
If you are still unsure, don’t risk a costly mistake. Our team at 85 Tope Street can help you confirm your boat’s requirements. We also provide advice on propeller pitch and diameter to ensure your new Honda or Suzuki performs at its peak.
© 2026 Wave Engines Pty Ltd. All motors are genuine Australian stock with full manufacturer warranty.