Where is the size/part number located on an outboard propeller?

When we are trying to dial in the correct propeller for a customer’s application, the two most important pieces of information we need are: What can the customer get for WOT RPM with the prop that is currently on there, and what is the current prop’s part number or diameter and pitch? Just knowing the motor size or serial number is usually not enough since every boat is different and in most cases there is not a stock prop that comes with the motor.

Ideally, we would like to know: The propeller manufacturer, propeller size, and propeller part number.

We often have customers tell us, “There isn’t a part number or size on the prop.” There usually is, you just need to know where to look and how to uncover it.

The easiest way to find the part number is to remove the prop from the boat so you can look at all angles and have good lighting. You also may need a razor blade or something to scratch off any growth, corrosion, or extra paint, in order to get a better view. If you can’t get a complete part number, a partial may help.

The size/part number are usually going to be in one of the following places:

• 1.On the outside of the hub between the blades (Image A).

• 2.On the aft end of the prop (the side furthest from the motor) underneath where the nut, aft spacer, or aft washer would go (Image B).

• 3.On the forward end of the prop (closest to the motor). This is not as common as the previous two locations (Image C).

• 4.On the forward side of one of the blades (closest to the motor). This is usually found on older, smaller OEM Japanese propellers (Yamaha, Suzuki, Honda).

The size is usually going to be in the following format:

Diameter X Pitch. For example, a 14.5x19 has a diameter of 14.5” and a pitch of 19.

Volvo Penta Duo Props don’t follow this format, instead they will usually have the series, size, and sometimes whether it is a front or rear. For example, “B3R” would mean it is a B series propeller, the size is 3, and it is the rear propeller (the rear on dual prop systems is the one farthest from the motor). See Image D.

Some OEM Yamaha propellers will just have a pitch and a series code embossed int the webbing between the prop hub and the prop body. It may look something like 19-K, which tells us it is a 19 pitch propeller in a “K” series prop (70-130 HP). See Image E.

Common part number code formats/examples:

Quicksilver - QA1916X, QS5002X, 8M0055536.

Mercury (may or may not contain “48” before the number) – 48 8M0151393, 77348A45.

Solas – 9571-155-15, 4113-100-07A.

Michigan Wheel (6 digits, or a letter and number code on older props) – 032042, 953421, PR21, PR-21.

Powertech – SCD3R17P-YM90, OFS3R21P-CL200

Volvo Penta (6 or 7 digits and may contain size, ex B3, and then a part number) – B3R 854832, 854832, F2 3857558, 3587558.