1. Propellers Boat Parts For Sale
  2. sku: 12157730229426793
  3. MERCURY 48-78120A40L

MERCURY 48-78120A40L Rh Prop Pitch Spline 3/4

fits make: Mercury. year: 2013–2019.

48-78120a40l Mercury Rh Aluminum Prop 13 3/4 X 19 Pitch 15 Spline 78120

( Manufacturer Part Number: 48-78120A40L ), ( Part Type: Aluminum Prop ), ( Propeller Rotation: Standard )

Review MERCURY Rh Aluminum Prop 3/4 Pitch Spline 78120 fits 2013–2019

The **Mercury 48-78120-A40L RH Prop 13 3/4" 19 Pitch 15 Spline** is a high-performance, right-hand drive (RH) propeller designed for marine applications, engineered to deliver exceptional efficiency, reliability, and power transfer in outboard and sterndrive systems. Crafted from durable, corrosion-resistant materials, this propeller features a **13 3/4-inch diameter** blade span, optimized for a balance of thrust and fuel economy, making it ideal for medium to large displacement boats ranging from fishing vessels and cruisers to performance-oriented personal watercraft. The **19-pitch** design ensures smooth acceleration and reduced cavitation, allowing the engine to operate at peak efficiency across a broad RPM range while minimizing wear and tear on the drive unit. With a **15-spline shaft connection**, this propeller is engineered for precise alignment and secure engagement, reducing the risk of slippage or misalignment that could compromise performance or lead to mechanical stress. The **A40L** designation indicates a specialized blade profile, featuring a refined hydrodynamic shape that enhances lift and reduces drag, contributing to improved speed, handling, and fuel efficiency. Whether deployed on a high-speed cruiser, a deep-sea fishing boat, or a versatile stern drive setup, this propeller excels in delivering consistent power delivery, smooth operation, and longevity, even under demanding conditions. Its robust construction and precision engineering make it a trusted choice for boat owners seeking a balance of performance and durability in their propulsion system.

### **Pros and Cons of buying a Mercury 48-78120A40L RH Prop (13 3/4" Pitch, 15 Spline)**

#### **Pros:**

1. **High Performance and Efficiency** This is a high-quality, marine-grade propeller designed for powerboats, offering excellent thrust and efficiency. The 13 3/4" pitch is well-suited for mid-range RPM applications, providing a balance between speed and torque.

2. **Durable Construction** Made from **7075-T6 aluminum**, this propeller is corrosion-resistant and built to withstand harsh marine environments. The **15-spline shaft** ensures a secure, vibration-dampening connection to the engine.

3. **Right-Hand (RH) Rotation** Designed for engines that rotate clockwise when viewed from the rear, ensuring proper thrust direction and compatibility with most outboard and sterndrive setups.

4. **Balanced for Smooth Operation** Properly balanced propellers reduce vibration, improving engine longevity and ride comfort.

5. **Aftermarket Support & Availability** Mercury Marine is a well-known brand with extensive aftermarket support, making replacements and tuning adjustments easier.

6. **Versatile for Different Applications** Works well on **V8, V6, and inline engines** in mid-sized powerboats, fishing boats, and cruisers.

7. **Customizable Options** Mercury offers different blade designs (e.g., cupped, flat, or hybrid) that can be swapped for performance tuning.

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#### **Cons:**

1. **Cost** As a high-performance propeller, it is more expensive than standard stock props, especially when purchased new. Prices typically range from **$300 $600 **, depending on dealer markup and customization.

2. **Potential for Damage** If not installed correctly or if the boat frequently runs aground, the blades can bend or crack. The 15-spline shaft is strong but not indestructible.

3. **Requires Proper Tuning** A poorly matched propeller (wrong pitch, RPM, or blade design) can lead to **poor fuel economy, excessive wear, or reduced speed**. Tuning may require professional assistance.

4. **Weight** Being made of aluminum, it is heavier than some plastic props, which could slightly affect handling in smaller boats.

5. **Limited Lifespan with Abuse** While durable, prolonged exposure to saltwater corrosion (if not properly maintained) can degrade performance over time.

6. **Installation Complexity** Requires proper alignment and torque specifications to prevent shaft damage or misalignment.

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### **Conclusion & Recommendation**

The **Mercury 48-78120A40L RH Prop (13 3/4" pitch, 15 spline)** is an excellent choice for boat owners seeking **high performance, durability, and efficiency** in a mid-sized powerboat. Its **aluminum construction, balanced design, and compatibility with Mercury engines** make it a reliable upgrade for those looking to optimize speed, fuel economy, and ride quality.

**However**, it is not the best option for:

- **Budget-conscious buyers** (due to higher cost).

- **Boats with extreme wear or frequent grounding** (risk of damage).

- **Those who cannot properly tune the propeller** (poor matching can negate benefits).

#### **Final Recommendation:**

- **Buy if:** You have a **Mercury-powered boat**, need better performance than stock props, and are willing to invest in proper tuning and maintenance.

- **Consider alternatives if:** You want a **cheaper option** (e.g., a high-quality aftermarket prop like **Volvo Penta or Mercury s own "Performance" line**) or a **lighter plastic prop** for smaller boats.

- **Best for:** **Fishing boats, cruisers, and performance boats** running at **2,500 3,500 RPM** with a **V6 or V8 engine**.

For optimal results, **consult a marine mechanic or propeller specialist** to ensure the correct pitch, RPM, and blade design for your specific engine and boat setup.

Details:

Hub is spun and needs replacement. Buyer Pays Return Shipping. Mercury RH Aluminum Prop 13 3/4 x 19 Pitch 15 Spline 48-78120A40L 78120.

part #: 4878120a40l prices

  • $25.00-$65.00

specifications propboapar:

  • for makes: Mercury
  • for years: 2013-2019
  • mpn: 48-78120a40l
  • part type: Aluminum Prop
  • propeller rotation: Standard

seller propboapar:

  • city: Gravois Mills, Missouri
  • # reviews: 545
  • rating: 99.6%

offer propboapar:

  • availability: In Stock
  • options: Ship-to-home
  • started: February 18, 2026
  • sold: 0
  • quantity: 1
  • best offers: True

shipping propboapar:

  • type: Calculated
  • class: Standard
  • cost: $15.62
  • service: USPS Ground Advantage
  • transit: 9-13 Days
  • carrier: USPS

returns propboapar:

  • policy: Returns Accepted
  • paid by: Buyer
  • time: 14 Days

payments propboapar:

  • other
  • wallet: Paypal
  • credit card: Discover

general propboapar:

  • Parts Accessories > Boat Parts > Propellers
  • condition: For parts or not working
for makes: mercury, for years: 2013-2019, part type: aluminum prop, propeller rotation: standard,
category: boat parts > propellers, sku: 12157730229426793,
Mercury 48-78120A40L Is Similar To:
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3 offers $25.00–$65.00 USD
  • Used. Offer #1 priced at $25.00 + $25.00 shipping estimate = $50.00* total. IT WILL FIT THE FOLLOWING ENGINES BELOW WITH A15 SPLINE PROP SHAFT,4.75" GEARCASE AND CORRECT MOUNTING HARDWARE.+$25.00 shipping
  • For parts or not working. Offer #2 priced at $50.00 + $16.87 shipping estimate = $66.87* total. +$16.87 shipping
  • Used. Offer #3 priced at $65.00 + $15.75 shipping estimate = $80.75* total. Make sure this will fit your application. Would make a great spare and put it on and go.+$15.75 shipping

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