Should you get a long-shaft or Short Shaft Outboard Motor after you know how much horsepower it has? Some yacht owners don't realize how important shaft length is, but experienced owners do. Choosing the wrong shaft length will make even the best outboard motor not work as well as it could. So, what are the distinctions between outboard engines with long shafts and those with short shafts?
What Does "Shaft Length" Mean?
The distance between the engine mount to the Anti-Ventilation Plate above the propeller is the shaft length. It tells you how deep the propeller will be in the water once the outboard motor is put in. The shaft length of a short tail outboard motor is 38 cm, the shaft length of a long tail outboard motor is 51 cm, and the shaft length of an extra-long-shaft outboard motor is 63 cm.
Why Shaft Length Matters So Much?
The length of the shaft needs to be the same as the height of the sternplate. If they don't match, the performance will be bad. For instance, if the shaft is too short, the propeller will be too close to the waterline, which may cause ventilation problems and loss of thrust. If the shaft is excessively long, the propeller will go too deep into the water, which will slow it down, use more fuel, and make it go faster. A shaft length that is right for the boat motor will make it work better and more efficiently, and it will also make it more safer.
Long Shaft Outboard Motor Vs Short Shaft Outboard Motor: Key Differences
1. Height Of Installation:
Short leg outboard motors work with boats that have a sternplate height of 38 cm, while long leg outboard motors work with boats that have a sternplate height of 51 cm.
2. Different Types Suitable For Different Waters:
Short-shaft boat motors work best in calm, shallow waters because they respond faster and are easier to handle. Long-shaft boat motors work best in rougher waves because they keep the propeller buried.
3. Different Types For Different Boat Types:
Short-shaft outboard engines work well with tiny inflatable boats, aluminium fishing boats, small boats, and service boats. Long-shaft outboard engines work well with fibreglass boats, center-deck boats, and deep-sea fishing boats.
4. Stability And Manoeuvrability:
Short-shaft boat engines are better for small boats because they are easier to steer and glide faster. Long-shaft boat engines are preferable for larger boats because they grab waves better and give more stable propulsion.
How To Choose The Right Shaft Length?
1. Measure The Height Of The Aft Plate:
Get an exact measurement of the distance from the bottom of the hull to the top of the stern plate and compare it to the normal shaft length.
2. Think About The Type Of Boat:
For inflatable boats, small aluminium boats, fibreglass fishing boats, and boats that travel to sea, short-shaft outboard motors are best.
3. Think About The Use:
Short-shaft outboard motors work better in calm lakes and rivers, while long-shaft motors work better in broad seas and turbulent waters, as well as on boats that are fully loaded.
Things To Stay Away From:
❌ Thinking that all outboard motors are the same.
❌ Not paying attention to the height of the stern plate.
❌ Picking only based on pricing.
❌Don't think that "longer shafts are always better."
❌ Don't forget about the water conditions.
Keep The Following In Mind While Choosing A Shaft Length:
① The anti-ventilation plate should be level with the hull.
② When you have to choose between two sizes, a shaft that is a little longer is usually safer, but you should be careful.
③ Always read the boat manufacturer's instructions.
④ Think about what the boat will be used for and how much it will carry.
Conclusion
Always think about the sternplate height, hull type, and operating conditions when picking a shaft length. Keep in mind that the length of the shaft and the length of the hull are the same. The process of choosing is not hard, but it is very important. Please get in touch with us for additional information about the Yamaha Enduro Boat Engine:
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FAQ
Q1: Can I put a long-shaft outboard motor on a small sternplate?
A1: No. Doing that will make the outboard motor work less well.
Q2: Is a long shaft always preferable than a short one?
A2: Not always; it depends on the boat.
Q3: What if the shaft isn't long enough?
A3: The propeller can break the surface, letting air escape and losing thrust.
Q4: How precise does the measurement need to be?
A4: Very accurate. A mistake of only a few inches can have a big effect on how well it works.
Q5: Can you change the length of the shaft after you buy it?
A5: You can't change it directly, but you can use a raise plate or sternplate extension to change the height of the outboard motor.
References
Wikipedia Outboard Motor