Propeller selection informationhow to choose a propeller

How to pick the right boat propeller:

  • Selecting the proper propeller for your boat is one of the most important tasks you as the boat owner must undertake.
  • To select the correct propeller, you need your boat loaded the way you use it normally. At full throttle, the engine must be able to reach the upper portion of its maximum rpm range. It should be able to reach this rpm range without excessive triming of the engine and with the boat on normal plane.
  • If your engine is matched with the correct size propeller, it will greatly extend its life. Targeting any other goal will derease its life.
  • For the best overall performance, select the largest diameter propeller available and select the pitch to allow the engine to max out the rpm at the top of its range.

High Performance Propellers:

  • For those of you who are into going fast, we will take a look at some choices.
  • A high performance propeller available from your local dealer is a propeller designed to allow your boat's engine to turn a larger diameter and pitched propeller than it physcially can. This is achieved in several ways. Some propellers have ventilation holes in the hub of the propeller that allow exhaust gases to bleed onto the surface area of the blades allowing them to slip. By slipping, the motor turns higher rpms and when coupled with larger pitch and diameter, this provides additional speed. One thing to note about these types of propellers. They do not operate well at lower rpm ranges and place a heavy load on the engine.
  • Another type of high performance propeller is the surface riding propeller. This is a specialty propeller used to get the most out of what you have. It is designed to operate with half of the blades out of the water. The result is higher rpms and speed. A light boat which is properly rigged, which may use a 19" propeller if rigged standard, may use a 26" or higher prop and reach speeds 20+ more than the standard prop achieved. If you choose this type of setup, be prepared to replace powerheads often.
  • Another aspect to look at in high performance propellers is bow and stern lift. As indicated, high performance propellers are available which lift either the bow or the stern of the boat. The purpose is to reduce the wetted surface area and drag, which allows more rpm and therefore speed. Choosing which one works for you depends on hull type and many other factors. Most "Vee" bottom high performance hulls, run with bow lift propellers, while tunnel hulls tend to use a combination.

 

How many Blades?

  • Todays propellers come in a wide variety of designs and blade configurations. The number of blades on your propeller will effect its effciency. More is not always better however. Three blades are the fastest propellers available, unless you have a heavy load. Beyond four blades, your getting no benefit other than a great holeshot, while giving up top end speed. You can't make a 5 or 6 blade propeller slip enough to gain rpm and allow a larger propeller selection.
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