Express Mach3 Propeller 13.75x15 – 3-Blade Stainless Steel, RH Rotation | 40–150hp (4.25" Gearcase)
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Express Mach3 Propeller — 13.75 x 15, 3-Blade Stainless Steel, Right-Hand Rotation
The Express Mach3 is a premium 3-blade stainless steel propeller built on nearly 40 years of race boat and high-performance prop design expertise. Machined from proprietary TP17™ stainless steel and engineered with aggressive pitch angles, radical blade geometry, and sharp cup profiles, it delivers best-in-class speed, handling, and acceleration for mid-range outboards and sterndrives from 40 to 150hp with 4.25-inch gearcases.
Best Use Case
The Mach3 in 13.75 x 15 pitch is an excellent all-around stainless upgrade for mid-horsepower outboards and sterndrives running 40–150hp engines with 4.25" gearcases. The 15-pitch delivers a strong balance of hole shot and top-end speed, making it well-suited to mid-weight fishing boats, bay boats, and runabouts where you want noticeably better performance than a stock aluminum prop — sharper acceleration, better fuel economy at cruise, and more confident handling. It’s also an ideal upgrade over older OEM stainless designs.
Why Upgrade to Stainless Steel?
Stainless steel propellers are significantly more durable than aluminum and deliver better all-around performance. The Mach3 runs within 0.5–1 mph of the equivalent Hustler aluminum design under most conditions, but holds that performance more consistently over time, resists flex under load, and outperforms competitive OEM and aftermarket stainless designs. In many cases, the fuel economy gains alone can offset the cost of the upgrade within a season or two.
Key Features
- TP17™ Proprietary Stainless Steel — Formulated specifically for the Mach3 and Mach4 series. 20% higher chromium content than standard stainless for better corrosion resistance and a higher-gloss finish. Nearly 250% stronger and 5x more durable than conventional stainless steel alloys.
- Performance-Tuned Geometry — Aggressive pitch angles, optimized rake, and sharp cup profiles engineered for maximum speed, acceleration, and handling.
- Tuned Exhaust Vents — Performance-optimized exhaust flow pathways reduce back-pressure and improve hole shot and top-end output.
- Race-Proven Finish — State-of-the-art casting and finishing processes drawn from race boat prop development.
- Broad Engine Compatibility — Fits Evinrude, Honda, Johnson, Mariner, Mercury, MerCruiser, Nissan, OMC, Parsun, Suzuki, Tohatsu, and Yamaha outboards and sterndrives.
Specifications
- Part Number: 31431512
- Diameter x Pitch: 13.75" x 15"
- Blades: 3
- Material: TP17™ Stainless Steel
- Rotation: Right-Hand (Standard)
- Gearcase: 4.25" (mid-large)
- Compatible Engine Range: 40–150hp outboards & sterndrives
- Hub System: 500-Series hub kit required (sold separately)
Parts Desk Insights
Hub kit required — not included. This propeller uses the 500-Series interchangeable hub system. Confirm your engine make, model, and year against the application chart to select the correct kit before ordering.
The 15-pitch is a mid-range choice for this gearcase family — a strong all-around starting point. If your engine is over-revving at wide-open throttle, step up to a higher pitch. If you’re struggling to reach your engine’s recommended RPM range, drop down to a lower pitch for more bite. Browse the Mach3 lineup for this gearcase:
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.