Right Boat Prop to Sail Through The Tide

Posted by veronikaadaam on June 4th, 2013

Selecting the correct prop

Boat propellers are perhaps the most important part of a boat. Choosing the right one is key to efficiently run your boat engine keeping it within its recommended rpm range allowing it to deliver the maximum horsepower. Unlike a car or bike a boat does not have multiple gears to switch between. The propeller size basically determines what gear you are driving in. There is no hard and fast chart to give you information about the choice you need to make. However, basic knowledge about the points you need to consider in while deciding is enough to make the right decision.

The following are some of the factors you must take into consideration while choosing a boat prop:

oSize- The boat props size is measured by its diameter and pitch. The diameter is basically twice the distance between the centre of the hub and edge of the blade. Pitch is the pushing power of the propeller. It is the distance covered by one complete revolution of the prop. Lower pitch will give greater acceleration while higher pitch will provide faster top speeds.

oNumber of propeller blades- 3 and 4-blade propellers are ideal for outboards and stern drives without much effect on the performance. If the number of blades is changed, the diameter and pitch must be adjusted to keep the RPM in the optimum range.

oMaterial- boat propellers are available in composite, stainless steel and aluminium. Composite boat props are reasonably priced, very durable and deliver good performance. Aluminium props are most widely used given the wide range of styles available. Stainless steel propellers are the most durable and deliver the highest performance.

oRPM- This is the most important factor you must consider. The prop must be able to maintain the RPM in the optimum range. The optimum range is about 5000 to 5500 RPM for outboards and 4400 to 4800 for stern drives. It is essential that the prop be able to maintain the RPM within this range. Only then will the engine be able to give maximum performance.

If you are about to replace your boat prop keep these above factors in mind. Further, if your boat prop is giving satisfactory performance and yet, you want to replace it, go with a propeller of the same diameter and pitch while upgrading to a stainless steel version and maybe, even a 4-blade prop.

If your engine over-revs with the present boat prop, chose a prop with a lower pitch and vice versa since the pitch of the boat prop is inversely proportionate to the RPM.

This is as much information as you will need to make an informed decision when buying boat propellers.