How to Pick a Boat Propeller
- 1). Decide on the aspects most important to you. If you are looking for a prop to fit a trolling motor you won't look for the same things you would in a speedboat prop, or for excellent handling in a cruiser.
- 2). Know the water you are most likely to be in. Props come in many different materials. Stainless steel and super strength stainless steel are long-lasting materials for props, but very expensive. These offer a lot of power. However, if you boat in water that has a lot of hazards, floating debris or shallow areas, the chances of damaging the prop are high, and it doesn't make financial sense to invest in extremely expensive props. Aluminum props are better for areas likely to get damaged, and are easier to fix. However, although they work well on lightweight boats, they may not be able to get a big, heavy cruiser up on plane.
- 3). Water-sports enthusiasts choose heavy, strong props made out of stainless steel because less flexibility is important when maneuvering at high speeds. Racing boats do better with stainless steel props, too. Both types of boats are less likely to do much traveling in areas with a lot of underwater hazards, so the expensive, strong props work best.
- 4). Pick the right number of blades. Props come in three- and four-blade styles. Three-blade props are the most common. They are the most affordable and work well for general boating. They have average planning abilities, are faster at top speeds, and come in many sizes. Four-blade styles produce a more stable ride, and are better for heavy seas. They push the boat up on plane faster, and keep it there easier with the least amount of speed. They accelerate faster, but do not have a fast top-end speed. The four-blade prop gives a more stable ride in a cruiser at low speeds.
- 5). Know in what direction your prop turns. Normally props turn in a clockwise motion. However, dual-engine boats have one prop that turns counter-clockwise and one that turns clockwise, so if one prop needs replacing you must know which one it is. Some modern engines have dual props on one shaft; one spins clockwise and the other counter-clockwise. The dual action of two props in opposition combats "slip" in the water and greatly improves control.
Prop and Pitch
- 1). Pick the right size and pitch. Your boat's prop is its transmission system. A boat, unlike ground vehicles, only has one mechanism to determine the speed in forward, or reverse: the prop. Determine what the diameter and pitch of the current prop on the boat is by examining it.
- 2). Props show their diameter and pitch on the label. A 13-inch prop with a 19-inch diameter will have a label that reads "13x19." Diameter is the distance of the circle created by the blade tips. The pitch is the forward propulsion the prop moves with one 360-degree rotation.
- 3). Know what your engine's limits are. The owner's manual has the information you need for maximum RPM (revolutions per minute). Increasing the pitch of the prop by only 1 inch will add 150 to 200 RPMs to the top end of your power. This gives your boat more speed, but also creates a hazard if it exceeds safe speed limits.
- 4). Learn the proper sound of your engine. If you know what your engine should sound like during peak performance, and how it should operate at all speeds, it will be easier to tell if you make the right choice in a new prop, or need to change to a different pitch or diameter.