You need to pick the right boat prop if you expect your boat to perform at its best. This means you need to pay special attention to the prop size, number of blades, the material used to make it, its rpm at wide open throttle, and the functions of the boat.
The size of the prop is an important factor. Installing the wrong size could damage the boat and its engine. The same goes for the ventilation and cavitation. The size is dependent on the prop’s diameter and pitch. You will see it on the hub. The first digit is for the diameter while the second one is for the pitch. When the boat is powerful enough, a higher pitch will boost the speeds travelled. A larger diameter will mean the boat accelerates much higher.
A prop can come with three to five blades. The more the number of blades, the better its performance. For higher top end speed, racing boats will need three bladed props. It is even better if they are cupped blades. Cupping is the curve at the end of a blade. It is what prevents ventilation and helps the boat make sharp turns. There is also the rake of the blade. The performance shall also be affected by the angle of the blade with the prop hub.
You need to then think of the material used to make the prop. Aluminum is what is commonly sourced and remains affordable. It is the lighter choice that shall also keep the boat safe when you hit obstacles. It however easily rusts and cannot stand salt water. Stainless steel would, but you would then have to pay a lot more for it. It is more durable and can withstand the effects of salt water. You can, however, be sure it will destroy the engine if you hit an obstacle. You shall need to have a composite and plastic prop for emergency cases.
Every engine shall also have its unique settings when it comes to rpm at wide open throttle. This should guide you as you make your choices.
You need to also think of the job the boat was designed to do. There are props designed for different types of boats, such as pontoons, bass boats, as well as those meant for skiing, fishing, racing or leisure. You need to also think of the water on which you shall use the boat. Some of these props are meant for the lakes, rivers, and other slow waters. Others are designed for the high seas. There shall also be the flat, heavy boats frequently used for transporting passengers and goods. There are some meant for high performance like racing.
Once you figure out such details, choosing a prop becomes much easier.