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Yamaha Propeller Identification
What Does the “K” Mean on a Yamaha Propeller?
Direct answer: On a Yamaha propeller, the letter K is a propeller-series or application code. In a marking such as 13 1/4 × 17-K, 13 1/4 is the diameter in inches, 17 is the pitch in inches, and K identifies the propeller series. K does not identify the material, and the letter alone cannot confirm that a replacement will fit.
Key Takeaways
- K is a series/application code, not a material grade.
- 13 1/4 × 17-K means 13 1/4-inch diameter, 17-inch pitch and K-series marking.
- Common K-series applications use a 4-1/4-inch gearcase and 15-tooth spline, but the engine model and year still matter.
- Check rotation, hub system, thrust washer and installation hardware before ordering.
- Use the stamped code as a starting point, not as the only fitment test.
How to Read a Yamaha 13 1/4 × 17-K Propeller Marking
Yamaha’s owner documentation uses a marking such as 13 × 17-K to show three separate pieces of information: propeller diameter, propeller pitch and the propeller mark. Yamaha’s propeller FAQ also explains that the numbers identify pitch while the letter code identifies the propeller series. On many propellers, the full diameter and pitch are stamped together.
| Marking | Meaning | What it does not confirm |
|---|---|---|
| 13 1/4 | Nominal propeller diameter in inches | Gearcase, spline count or hub hardware |
| 17 | Nominal pitch in inches | Actual WOT RPM on a specific boat and load |
| K | Yamaha propeller series/application code | Material, final fitment or rotation by itself |
What Does the Yamaha K Code Identify?
The K code tells a Yamaha dealer or parts specialist which propeller family and application range the propeller belongs to. Yamaha describes these letters as series codes: the code groups propellers designed around a particular range of outboard and gearcase applications.
That is why a K stamp is useful when replacing a damaged propeller. It narrows the search to the correct family. However, it is not a complete fitment specification. Two propellers can share a pitch or even a K-series description while differing in blade design, rotation, hub construction or required hardware.
Fitment warning: Do not order only by horsepower or by the letter K. Confirm the exact engine model and year, gearcase size, propeller-shaft spline count, RH/LH rotation, diameter, pitch, hub system, thrust washer and spacer/nut hardware.
Yamaha K-Series Propeller Fitment Checklist
Common K-series applications are associated with Yamaha’s midrange 4-1/4-inch gearcase family. Yamaha’s current propeller information lists K-series 4.25-inch gearcase applications in the F70–VF115 and T50/T60 range for certain propeller families. Older Yamaha application tables also show K-marked propellers across additional engine models. This is why model-year verification is essential.
- Record the engine model and serial information. Do not rely on the cowling horsepower label alone.
- Confirm the gearcase. Common K-series applications use a 4-1/4-inch gearcase, but exceptions and older applications must be checked.
- Count the splines. Xspeed’s common Yamaha 50–130 HP replacement group uses a 15-tooth spline.
- Check rotation. Most single-engine applications are RH, while some counter-rotation installations require LH.
- Read the complete marking. Record diameter, pitch and the letter code, plus any part number visible on the hub or barrel.
- Inspect the hub and hardware. Verify the hub type, thrust washer, spacer, washer and propeller nut arrangement.
- Confirm WOT RPM. Yamaha advises choosing pitch so the engine operates within the specified full-throttle range under the normal maximum boat load.
If any of these details are uncertain, use the Xspeed Propeller Fitment Finder and send the technical team a photo of the existing propeller marking and the engine identification plate.
Does K Mean Aluminum or Stainless Steel?
No. The K letter does not mean aluminum, stainless steel or another material. It identifies the Yamaha propeller series/application family. Material must be confirmed separately from the propeller construction, part number or product specification.
Xspeed offers replacement options for common Yamaha midrange applications in both aluminum propellers for common Yamaha 50–130 HP applications and stainless-steel propellers for common Yamaha 50–130 HP applications. These are application groupings, not a statement that every engine from 50 to 130 HP uses the same propeller.
| Material | Typical selection reason | Fitment items still required |
|---|---|---|
| Aluminum alloy | Lower replacement cost, lower rotating mass and practical service use | Gearcase, spline, rotation, diameter, pitch and hub hardware |
| Stainless steel | Higher stiffness, thinner blade sections and corrosion resistance for demanding use | Gearcase, spline, rotation, diameter, pitch, hub system and engine operating range |
How to Choose an Aftermarket Replacement for a 17-K Propeller
Start with the complete existing marking and engine data. A 17-K marking tells you the propeller has 17-inch pitch and belongs to the K series, but diameter may be stamped elsewhere and must also be recorded. Then compare the engine application, gearcase diameter, 15-tooth or other spline specification, RH/LH rotation and hub requirements.
When replacing like-for-like, keep the same pitch only if the previous setup placed the engine within Yamaha’s recommended WOT RPM range under the normal load. If RPM was too low, too high, or the boat’s load and use have changed, pitch selection needs a separate performance review. Do not treat a pitch change as a fitment shortcut.
Cross-reference note: OEM references such as Yamaha 6E5-series part numbers can help identify a common K-series aluminum application. Always treat an OEM number as a cross-reference and verify the full specifications. Xspeed products are aftermarket replacement products, not genuine Yamaha parts.
Check Your Yamaha Propeller Specifications
Use the Finder for a first-pass match, or send the engine model, year, current propeller marking, gearcase and spline information for technical confirmation.
Frequently Asked Questions
What does 13 1/4 × 17-K mean on a Yamaha propeller?
It indicates a nominal 13 1/4-inch diameter, 17-inch pitch and Yamaha K-series/application marking. It does not, by itself, confirm material or final fitment.
Does the K on a Yamaha propeller mean stainless steel?
No. K is a propeller-series/application code. Aluminum and stainless-steel replacement choices must be identified separately.
Are all Yamaha K-series propellers 15 spline?
Many common midrange K-series applications use a 15-tooth propeller shaft and 4-1/4-inch gearcase, but the exact engine model, year and propeller design must be verified. Do not assume spline count from the letter alone.
Can a 17-K propeller be replaced with any other 17-pitch propeller?
No. Matching pitch alone is insufficient. Diameter, gearcase, spline count, rotation, hub system, hardware and engine application must also match.
Where is the Yamaha propeller code stamped?
The marking is commonly stamped on the propeller barrel or hub area, but its exact location can vary. Check around the outer barrel and near the hub, and photograph every number and letter before ordering.
Sources and References
- Yamaha Outboards — Propellers FAQs
- Yamaha F80A/F100A Owner’s Manual — propeller marking and selection guidance
- Yamaha Outboards — Propellers for Medium & Small Boats
- Xspeed Master Propeller Database V5 — Yamaha 50–130 HP application grouping, checked August 3, 2026
Yamaha is a trademark of Yamaha Motor Co., Ltd. Xspeed products are aftermarket replacement products and are not genuine Yamaha parts. Compatibility information is provided for cross-reference purposes and must be confirmed against the engine model, year, gearcase, propeller shaft, rotation and installation hardware.