Express Mach4 4-Blade Stainless Steel Propeller – 15" x 15" | Left Hand (Counter) Rotation

Express Mach4 4-Blade Stainless Steel Propeller – 15" x 15" | Left Hand (Counter) Rotation

The Express Mach4 15" x 15" Left Hand is the counter-rotation version of the Mach4 15x15, designed for twin-engine setups where one engine requires a left-hand (counter-clockwise) rotating propeller. It shares the same Dual Geometry blade design, TP17™ stainless steel construction, and performance characteristics as the right-hand version — delivering 4-blade acceleration and stern lift without sacrificing 3-blade top-end speed.

If you’re running a single-engine application, see the Express Mach4 15" x 15" Right Hand instead.

Key Features

• Left Hand (counter) rotation — Designed for the port-side engine in twin-engine configurations that require counter-rotating props for balanced handling and reduced torque steer.
• Dual Geometry blade design — Two blades use a high-performance variable rake profile for hole shot and cornering; two use an offshore-style design for top speed and maximum stern lift. 4-blade handling with 3-blade top-end speed.
• Proprietary TP17™ stainless steel — 20% higher chromium content than standard stainless for superior corrosion resistance and a higher-gloss finish. Nearly 250% stronger and 5x more durable than conventional stainless steel.
• Lifts the hull higher under load — Increased stern lift reduces wetted surface area, minimizing speed loss when the boat is fully loaded — where a three-blade can lose up to 3 mph.
• Large free-flowing exhaust ports — 40% more exhaust flow area than competing designs reduces backpressure and improves horsepower delivery and hole shot.
• Wide engine compatibility — Fits COX®, Evinrude®, Honda®, Johnson®, Mariner®, Mercury®, MerCruiser®, Nissan®, OMC®, OXE®, Parsun®, Suzuki®, Tohatsu®, Volvo Penta®, and Yamaha® outboards and sterndrives.

Specifications

• Diameter x Pitch: 15" x 15"
• Blades: 4
• Material: TP17™ Stainless Steel
• Rotation: Left Hand (Counter)
• Gearcase Fit: 4.75"
• Engine Range: 90–300+ hp
• Hub System: 500 Series (under 200 hp) or 700 Series (200+ hp) — sold separately

Hub Kit Required

A MasterGuard installation hub kit is required and sold separately. Use the 500 Series for engines under 200 hp, or the 700 Series for engines 200 hp and above. Mercury Verado® and ProXS® owners with a 1.25" fat shaft will need the MasterTorq® 621 FSH Fat Shaft Hub Kit instead. Refer to the application chart for your engine’s required kit number.

• MasterGuard Hub Kit 500 – 500 Series
• MasterGuard Hub Kit 502 – 500 Series
• MasterGuard Hub Kit 506
• MasterGuard Hub Kit 508
• MasterGuard 700 Series Hub Kit – 200+ hp

Right Hand Version & Related Models

• Express Mach4 15" x 15" – Right Hand Rotation
• Express Mach4 14" x 19" – RH (4.75" Gearcase)
• Express Mach4 14" x 21" – RH
• Express Mach4 15.3" x 13" – RH (4.75" Gearcase)
• Express Mach3 14.25" x 19" – 3-Blade Stainless RH
• Express Mach3 14.25" x 19" – 3-Blade Stainless LH

Parts Desk Insights

Best use case: This is the correct prop when a customer with a twin-engine setup needs the port-side (counter-rotation) version to pair with the Mach4 15" x 15" RH on the starboard engine. Counter-rotation props are critical for twin-engine balance — running two right-hand props on a twin-engine boat causes torque steer and handling issues. Always confirm the customer’s engine configuration and which side requires counter rotation before selling. The performance profile is identical to the RH version: best suited to high-horsepower applications (90–300+ hp) on heavier hulls, loaded boats, watersports, tri-toons, and sterndrives where hole shot, stern lift, and load-carrying performance are priorities. Hub kit selection follows the same rules as the RH version — confirm engine HP and shaft type before recommending a kit number.