Your Ultimate Guide to Finding the Perfect Long Shhaft Outboard Engine for Sale

Tired of your outboard cavitating in rough water or struggling on a high-transom boat? That frustrating loss of power just when you need it most isn’t a sign of a bad engine—it’s a sign of the wrong engine. The solution lies in understanding shaft length, a critical specification many boat owners overlook.

A long shaft outboard engine is a motor with a longer driveshaft—typically 20 inches—specifically designed for boats with higher transoms. This extra length ensures the propeller remains properly submerged, delivering optimal power, efficiency, and control. Models with an extra-long 25-inch shaft are also available for even taller transoms, commonly found on sailboats and large offshore vessels.

This comprehensive guide will help you understand if you need a long shaft, what to look for when buying, and where to find the best deals on reliable long shaft outboard engines for sale.

What Is a Long Shaft Outboard? (And Do You Really Need One?)

Choosing the correct shaft length isn’t about preference; it’s about physics and geometry. Getting it wrong means sacrificing performance, safety, and fuel efficiency.

The Simple Science: Shaft Length and Transom Height

The relationship is straightforward: your engine’s shaft length must match your boat’s transom height. The industry standard shaft lengths are:

• 15-inch (Short Shaft): For standard outboard boats and smaller craft.
• 20-inch (Long Shaft): The most common “long shaft” for larger runabouts, center consoles, and boats with elevated transoms.
• 25-inch (Extra-Long or Ultra-Long Shaft): For sailboats, rigid inflatable boats (RIBs), and commercial fishing vessels with very high transoms.

How to Measure Your Transom Height:
1. Have your boat on a level surface, either on a trailer or in the water.
2. Using a tape measure, find the point where the outboard would be mounted.
3. Measure vertically from the top of the transom (the mounting point) down to the bottom of the hull (the keel).
4. This vertical measurement is your transom height. Match it to the corresponding shaft length.

Signs You Need a Long Shaft Outboard Engine

Your boat will tell you if the shaft is too short. Watch for these clear symptoms:

• Propeller Ventilation (Cavitation): The propeller sucks in air, especially in turns or choppy water, causing the engine to over-rev and a sudden loss of thrust.
• Excessive Splashing: Water sprays up around the transom instead of flowing cleanly to the propeller.
• Poor Handling and Lack of Thrust: The boat feels sluggish and struggles to get on plane, as the propeller isn’t gripping solid water.

If you experience any of these issues, switching to a correctly sized long shaft engine will feel like getting a brand new boat.

Key Considerations Before You Buy

Once you’ve confirmed you need a long shaft, the next step is selecting the right engine for your needs.

Horsepower (HP) and Your Boat’s Requirements

Matching horsepower to your boat is crucial for safety, performance, and efficiency. While you should always consult your boat’s capacity plate, here is a general guideline:

Boat Size & Type	Recommended HP (Long Shaft)
14-16 ft. Jon Boat / Skiff	15 – 25 HP
16-18 ft. Center Console / Runabout	50 – 90 HP
18-22 ft. Deep-V Fishing Boat	115 – 150 HP
22-26 ft. Pontoon / Sailboat (Auxiliary)	9.9 – 25 HP
24+ ft. Offshore / Commercial	150 – 300+ HP

2-Stroke vs. 4-Stroke: Making the Right Choice

The debate between 2-stroke and 4-stroke engines is still relevant, especially in the used market.

• 2-Stroke Engines:

  • Pros: Lighter weight, simpler mechanics, higher power-to-weight ratio.
  • Cons: Less fuel-efficient, higher emissions, requires oil-gas mixture (in older models).
  • Best For: Anglers who prioritize a lightweight setup for frequent loading/unloading.

• 4-Stroke Engines:

  • Pros: Superior fuel efficiency, quieter operation, cleaner emissions, no oil mixing.
  • Cons: Heavier, more complex (and costly) to repair.
  • Best For: Most boaters, especially those who value fuel economy, quiet trolling, and environmental friendliness.

Modern direct-injection 2-strokes bridge this gap, but the market has overwhelmingly shifted towards 4-stroke technology for reliability and efficiency.

New vs. Used Long Shaft Outboards

This is a significant financial decision. Weigh the pros and cons carefully.

• New Outboards:

  • Pros: Full manufacturer warranty, latest technology and fuel efficiency, zero wear and tear, financing options.
  • Cons: Highest upfront cost, significant depreciation in the first few years.

• Used Outboards:

  • Pros: Lower initial investment, slower depreciation.
  • Cons: No warranty (or a short remaining one), unknown maintenance history, potential for hidden issues.

For most buyers, a new engine from an authorized dealer is the safest bet. However, a well-maintained used engine from a reputable source can offer exceptional value.

Top Long Shaft Outboard Engine Brands for Sale

When investing in a long shaft outboard, brand reputation matters. Here are the industry leaders known for their reliability and performance.

Yamaha: Reliability and Innovation

Yamaha has built a sterling reputation for building virtually bulletproof engines. Their long shaft models, from the high-thrust F25 to the powerful V6 V8 SHO series, are renowned for corrosion resistance and digital electronic controls. They are a top choice for boaters who prioritize dependability above all else.

Suzuki: Fuel Efficiency and Performance

Suzuki has aggressively captured market share with its innovative lean-burn technology, making some of the most fuel-efficient engines on the water. Their long shaft options offer an excellent power-to-weight ratio, making them a favorite for performance-conscious anglers and commercial operators looking to save on fuel costs.

Mercury: A Legacy of Power

As an American icon, Mercury offers a vast range of long shaft outboards. From the compact 9.9HP FourStroke to the brutish 400HP Verado, Mercury engines are known for their strong mid-range torque and robust construction. Their dealer network is one of the most extensive, a key consideration for service and support.

Honda: Quiet and Eco-Conscious

Honda’s mantra of reliability from their automotive division carries over to their marine engines. Their 4-stroke long shaft outboards are famously quiet, smooth, and eco-friendly. They are the go-to for sailors needing an auxiliary power source and for any boater who values a peaceful day on the water.

Expert Tips for a Smart Purchase

This is where experience separates a great deal from a money pit. Having inspected and sold hundreds of outboards, here is our actionable advice.

The Pre-Purchase Inspection Checklist

Never buy a used outboard, especially a long shaft model, without going through this list.

1. Compression Test: This is non-negotiable. Rent a gauge. All cylinders should be within 10% of each other (e.g., 120, 118, 122 PSI is good; 150, 90, 145 is very bad).
2. Lower Unit Oil Inspection: Drain a small amount of gear oil from the lower unit into a clean container. Look for a milky appearance (indicates water intrusion) or metal shavings on the drain plug magnet (indicating gear wear).
3. Visual Corrosion Check: Pay close attention to the mounting brackets, engine cowl latches, and around the water intake ports. Surface rust is normal; pitting and heavy corrosion are red flags.
4. The Freshwater Test Run: If possible, insist on a test run. Listen for smooth idle and acceleration. Check that the “pee-hole” has a strong, steady stream of water, indicating a healthy cooling system. Observe the gear shift for smooth engagement.

Where to Find Trustworthy Sellers

Your source is as important as the engine itself.

• Authorized Dealers: This is the safest route for a new engine. You get the warranty, and the setup is done by certified technicians. Explore the range at https://hidea-outboardmotor.com/dealers.
• Reputable Online Marketplaces: Sites like Boat Trader, iBoats, and The Hull Truth have established reputations. Always check the seller’s history and reviews.
• Word of Mouth & Local Marinas: Often, the best deals are found through local networks.

A Critical Warning: Be extremely wary of deals that seem too good to be true on general classified sites (like Craigslist or Facebook Marketplace). Never wire money. Insist on seeing the engine in person and completing the checklist above. Scammers often use stolen photos and pressure you to act fast.

Frequently Asked Questions (FAQ)

Q: What is the difference between a long shaft and a short shaft outboard?
A: The primary difference is the length of the driveshaft, which is 20 inches for a long shaft versus 15 inches for a short shaft. This extra 5 inches is crucial for ensuring the propeller stays submerged on boats with a higher transom, preventing cavitation and loss of power.

Q: Can I convert a short shaft outboard to a long shaft?
A: While technically possible for some older models by replacing the driveshaft, midsection, and water tube, it is a complex, labor-intensive job that is rarely cost-effective. The parts can be hard to find and expensive. We strongly recommend buying an engine designed with the correct shaft length from the factory.

Q: What is the typical price range for a long shaft outboard for sale?
A: Prices vary dramatically based on horsepower, age, and condition. A used 9.9HP 4-stroke long shaft might start around $1,500, while a new 25HP model can be $5,000 – $7,000. High-horsepower commercial long shaft engines (150HP+) can easily exceed $15,000.

Q: Are long shaft outboards harder to steer or handle?
A: They can be slightly heavier and have a slightly higher center of gravity, which might be noticeable on a very small boat. However, this is a minor trade-off for the massive performance and safety gain on the correct hull. For larger engines (over 100HP), hydraulic or power-assisted steering is standard and eliminates any handling concerns.

Conclusion & Next Steps

Choosing the right long shaft outboard engine boils down to a few critical steps: accurately measuring your transom height, selecting the appropriate horsepower and fuel type for your needs, and, most importantly, purchasing from a reputable source. A properly matched engine transforms your boating experience, providing the reliable, efficient power you deserve.

Ready to stop battling cavitation and start enjoying smooth, powerful performance? Browse our curated selection of new and pre-inspected long shaft outboard engines for sale at https://hidea-outboardmotor.com/outboards and find your ideal match today.