What Pitch Propeller Do I Need for Top Speed?

What Is Propeller Pitch?

Propeller pitch refers to the distance (in inches) a propeller would move forward in one full revolution without slip — like a screw going through wood. For example:

• A 21-inch pitch propeller theoretically moves 21 inches forward per revolution.

In real-world boating, water resistance and load reduce that distance. This is called prop slip.

🧠 How Pitch Affects Speed (and Engine Health)

Choosing the right pitch isn’t just about speed — it also protects your engine. Here’s how:

Your goal is to balance pitch with your engine’s Wide Open Throttle (WOT) RPM range — usually listed in the owner’s manual. A mismatch means you’ll either lose speed or risk engine damage.

🛠️ Step-by-Step: How to Choose the Right Propeller Pitch for Top Speed

✅ 1. Know Your Engine’s WOT RPM Range

Every outboard motor has a recommended WOT RPM range — usually something like 5,200 to 6,000 RPM. You need a prop that lets your engine hit that range at full throttle.

✅ 2. Check Your Current RPM and Speed

Run your boat at full throttle and record:

• GPS speed

• RPM reading

If your RPM is too low, you likely need a lower pitch prop.
If it’s too high, go for a higher pitch to reduce RPM and increase speed.

✅ 3. Use the 150–200 RPM Rule

Changing prop pitch by 1 inch will typically change your engine RPM by 150–200 RPM.

Example:

• Current prop: 19″ pitch

• WOT RPM: 6,400 (too high for a 6,000 limit)

• New pitch recommendation: 20″ or 21″

✅ 4. Consider Your Load & Usage

Are you running solo or carrying gear and passengers? More load = more drag = you may need less pitch. Want max speed on flat water? Go higher — if your engine can handle it.

🚤 Real Example: Yamaha 150hp Outboard

Let’s say you’re running a Yamaha 150hp outboard on a 19-foot fiberglass boat.

• WOT range: 5,000–6,000 RPM

• Current prop: 19″ pitch, hitting 5,700 RPM

• You want more speed — but you’re near max RPM.

• Solution: Try a 20″ or 21″ pitch prop, retest speed and RPM, and see what works best.

This process is how we help customers at Meridian Outboard Motor dial in the right propeller every time.

📊 Quick Reference: Best Pitch by Use Case

Remember: More pitch ≠ always better speed — your engine must be able to turn it efficiently.

🧪 Pro Tip: Use a Propeller Calculator

To simplify your decision, use our Propeller Pitch Calculator (coming soon to MeridianOutboardMotor.com). It will estimate ideal pitch based on:

• Boat weight

• Engine horsepower

• Current RPM

• Desired speed

Until then, reach out to our support team for free advice.

🧾 Bonus: How to Read Propeller Size

Most props have a number stamped like this:
13 ¾ × 21

• 13 ¾ = diameter (in inches)

• 21 = pitch

Knowing this helps you compare options or upgrade intelligently.

🧰 Propping Tips from the Experts at Meridian Outboard Motor

• Always test under typical load conditions

• Avoid guessing — always measure RPM

• Stainless steel props often give better speed and efficiency than aluminum

• When in doubt, drop pitch before you raise it — it’s safer for your engine

• Keep your old prop as a backup or for towing/utility use

🙋 Frequently Asked Questions (FAQs)

❓ What happens if my pitch is too high?

Your engine may “lug” — failing to reach proper RPM — and your boat will feel sluggish despite wide-open throttle.

❓ Can changing pitch really affect speed that much?

Yes! A 1″ pitch change can add or subtract several mph — especially on lighter boats or when finely tuned.

❓ Should I go for 3-blade or 4-blade prop for speed?

For top speed, a 3-blade prop is usually faster. A 4-blade gives better control and acceleration, but may shave 1–2 mph off top end.

❓ What pitch prop is best for a 150hp outboard?

It depends on your boat type, load, and RPM. Most fall in the 17″–21″ range, but test and tune for the best result.

❓ Can Meridian Outboard help me choose a prop?

Absolutely! We offer free propeller consultations and ship performance-tested props for most outboard brands. Contact us here.

🏁 Final Thoughts: Go Fast, But Go Smart

If you’re chasing top speed, pitch is everything — but only when matched to your engine’s powerband. Don’t waste money on guesswork. Let MeridianOutboardMotor.com help you pick the right prop, dial in performance, and maximize your time on the water