Propeller 101: SOLAS and RUBEX Part Numbers


Ever wonder what all those numbers mean on your propeller? Here is a breakdown of the SOLAS propeller part numbers.

Propeller 101: Diameter and Pitch


Propeller Size

Propellers are sized and described by their diameter and pitch. A propeller listed as a 15 ? x 17 x 3 would indicate a 17 inch pitch, 3 blade propeller having a diameter of 15 ? inches. Pitch is the theoretical distance that the boat will move forward with each revolution of the prop shaft, minus the slippage. The pitch ultimately is responsible for the top speed of the boat, much like the main jet in a carburetor is responsible for the ultimate power and speed of an engine.

The pitch must be matched to the engine’s recommended rpm range for full throttle. For most engines, this top range is about 500 to1000 rpm (typically 5,000-5,500 for 2-strokes, 5,000-6,000 for 4-strokes). A light boat and load will pull a high numerical pitch prop, whereas a heavy boat and load would have to run a smaller numerical pitch to load the engine less and allow the engine to reach recommended full throttle rpm. Keep in mind that most propeller manufacturers design their pitch in a progressive manner, to the point that the actual pitch will vary across the blade surface. Also, keep in mind that different propeller manufacturers each measure their pitch in slightly different ways with different tolerances. This means that two propellers of the same diameter and pitch from two different companies can yield different performance data.

For anglers slow-trolling for species like rockfish and flounder, a propeller with lower pitch (less distance per turn) that still allows the engine to rev to the top of its range will offer lower trolling speeds. It will also push loads easier and make maneuvering around a dock easier. On the other hand, a prop with more pitch that lets the engine turn to the lower end of its range may yield higher top speed

Propeller 101: Aluminum vs Stainless Steel


Solas aluminum propellers use an exclusive squeeze-cast process to make them more durable and non-porous compared to traditional die cast propellers on the market. Solas stainless steel propellers are made with the industry’s highest percentages of chromium, nickel and molybdenum, resulting in a propeller that is more durable, highly rust-resistant and less brittle.

Propeller 101: Using the Rubex Prop Finder


The Rubex Prop Finder is a valuable tool to help in finding a propeller for your boat.

Propeller 101: 3 Blade or 4 Blade


3 blade propellers can provide greater top end speed. 4 blade propellers can provide better acceleration and thrust which help get the boat to plane and keep it there at lower speeds. With 4 blade propellers, you may gain bottom and mid-range performance while sacrificing top end.

Propeller 101: SOLAS VS RUBEX


Solas propellers are designed to replace a specific engine manufacturer application. It comes with a pressed in-rubber hub already installed which allows you to use the original hardware that came with your engine. Rubex propellers are designed with an interchangeable rubber hub to match a wide variety of outboard and sterndrive engines.

© Solas Science & Engineering Co., Ltd. All Rights Reserved