12 1/4 x 15 13-Spline Aluminum Boat Propeller RH JSPROP

In this review of the OEM Upgrade 12 1/4x15 propeller the bottom line is simple: this is a practical replacement for owners of Johnson and Evinrude outboards in the 40-75 HP range who need a correctly sized, easy-to-install spare. The reviewer found the propeller delivers reliable fit and noticeably improved throttle response for routine recreational use, and the focus on a 13 spline, 12.25 in diameter and 15 in pitch ensures it matches common OEM references such as 778774. It is presented as a straightforward, value-minded upgrade rather than a high-end performance part.

Key Features

• Correct fit specification: The 13 spline, 12 1/4 in diameter by 15 in pitch design ensures compatibility with Johnson and Evinrude 40-75 HP engines when the previous propeller uses the same reference.
• Right-hand rotation: The RH three-blade configuration provides conventional handling and predictable steering response for most single-prop sterndrive setups.
• Aluminum construction: A lightweight aluminum build gives a balance of durability and lower cost while keeping acceleration and top speed acceptable for recreational boats.
• Anti-corrosion coating: The black patented coating improves resistance to corrosion and extends service life in salt and fresh water conditions compared with bare metal props.
• Includes hardware and hub: The propeller is supplied with an interchangeable hub and required hardware, making installation straightforward for owners with basic tools.

Who It's For

This propeller is aimed at boat owners running Johnson or Evinrude outboard or sterndrive engines between 40 and 75 HP who need an accurate replacement for reference 778774. It is best for recreational anglers, small sport boat operators, and weekenders who prioritize value, ease of installation, and reliable everyday performance.

It is not intended for high-performance racing applications or owners seeking exotic materials or custom blade geometry to chase top-end speed gains; those buyers should look for specialized stainless or performance-tuned props instead.

Pros & Cons

Pros

• Good fit: matches the 13 spline and 12.25 in x 15 in specs for a direct replacement on compatible engines.
• Value for money: customers report the prop offers solid performance and fit at a lower price than OEM equivalents.
• Easy installation: supplied hub and hardware simplify swap-outs during routine maintenance.
• Durable finish: patented anti-corrosion coating helps longevity in marine environments.

Cons

• Aluminum rather than stainless: durable for normal use but not as resistant to damage from impacts as harder alloys.
• Not a performance-tuned prop: buyers seeking maximum top speed gains may find limitations compared with specialized designs.

Specifications

Our Verdict

For owners of Johnson and Evinrude engines who need a dependable, correctly sized replacement, this 12 1/4 in x 15 in, 13-spline propeller represents good value and straightforward performance. It installs easily, resists corrosion better than bare aluminum, and restores reliable throttle response for everyday boating, making it a sensible choice for routine use.

Frequently Asked Questions

Will this prop fit my Johnson or Evinrude engine?
Check that your old propeller is 13 spline with a 12 1/4 in diameter and 15 in pitch and that the engine power range is 40-75 HP; if those match, this prop is intended to be compatible.

Is the propeller ready to install out of the box?
Yes, it ships with an interchangeable hub and the necessary hardware so most owners can install it with common tools.

How durable is the finish?
The propeller uses a patented black anti-corrosion coating to extend service life in both fresh and salt water compared with uncoated aluminum.