The selected boat propeller determines how well a boat shall perform. When choosing a boat propeller, there are some things you have to consider. You need to think of its size, number of blades, the material it is made out of, its RPM at the wide open throttle, and the use of the boat.
Of all these, you need to be most keen on the prop size. Choosing the wrong size often leads to a damaged boat and engine. You need to look at the boat prop’s diameter and pitch when gauging its size. The higher the pitch, the more speed the boat shall manage, given it has a powerful engine. Those with a larger diameter, however, manage to accelerate much faster.
There are props with three to five blades. A higher blade count means the boat shall manage even better performance. The lesser the number of blades, the more top speed it can reach. You will thus see most racing boats with three bladed props only. If it is cupped blades, even better. Cupping points to the curve at the end of the blade that helps the boat make sharp turns. There is also the rake of the blade to think of. The angle between the prop hub and blade is the rake. It aids in minimizing slipping.
The material used in making the prop matters. Aluminum props are easily found and are cheaper. They make for lightweight and strong props. They are however not good for use in salty water. You would need to go for stainless steel there. Those are not as cheap. They also present the danger of damaging the entire engine system, which is not the case with aluminum props. There are also composite and plastic props, which serve their purpose well in case of an emergency.
When it comes to the RPM at the wide open throttle, there are specifications for each engine and boat. There are manuals from which you can refer for more info on this.
The purpose of the boat is the other factor you need to consider. There are many prop types out there, meant for different uses. You shall find some designed for pontoons, bass boats, and skiing boats, those for fishing, racing, or relaxation. The kind of water the boat shall be traveling also matters. Some props are great for lakes, while others are ideal for rivers or slow-moving waters. You will find a selection meant for the high seas. Some are specially designed for flat, heavy passenger or goods boats. There are all manner of uses for these props, which must be factored in the purchase. You should also get an extra prop, in case an emergency comes up.