Finding the right propeller for Yamaha 115 outboard motors is one of those things that seems simple until you're staring at twenty different options and wondering why your boat suddenly feels sluggish. It's arguably the most important piece of gear on your boat because it's the only part that actually translates all that engine power into movement. If you've got a Yamaha 115—which is basically the "goldilocks" engine for mid-sized boats—you want to make sure you aren't leaving performance on the table by running the wrong wheel.
I've spent a lot of time talking to folks at the docks who complain that their boat "just doesn't have the get-up-and-go it used to," only to find out they're running a prop that belongs on a completely different hull. The F115 is a legendary workhorse, but it's sensitive to how it's propped. Let's break down how to pick the right one without getting bogged down in too much technical jargon.
Understanding the Basics: Pitch and Diameter
When you start looking for a propeller for Yamaha 115 outboard engines, you'll see two numbers stamped on the side, like "13 x 17" or "13-1/4 x 19." The first number is the diameter, which is just the total width of the circle the blades make. For a 115hp, you're usually looking at something in the 13 to 14-inch range. It matters, but it's not the number that usually trips people up.
The second number is the pitch, and that's the big one. Think of pitch like the gears on a bicycle or a car. A lower pitch (like a 15) is like a low gear; it gives you tons of "holeshot" or pulling power, which is great if you're pulling tubers or have a heavily loaded boat. A higher pitch (like a 19 or 21) is like a high gear. It's better for top-end speed, but it takes longer to get the boat up on plane.
If you go too high on the pitch, you'll "lug" the engine, which is terrible for a Yamaha 115. It's like trying to start your car in fifth gear from a stoplight. If you go too low, you'll hit the rev limiter before you even get moving fast. You want to find that sweet spot where your engine can hit its recommended Wide Open Throttle (WOT) RPM—usually between 5,000 and 6,000 RPM for these Yamahas.
Aluminum vs. Stainless Steel: Which Is Better?
This is the age-old debate at the bait shop. Most Yamaha 115s come from the factory with an aluminum prop. They're affordable, easy to repair, and they're actually designed to fail. That sounds weird, right? But if you hit a rock or a stump, the aluminum blades will usually bend or break off, which protects the expensive gears inside your lower unit.
On the flip side, a stainless steel propeller for Yamaha 115 outboard setups offers much better performance. Stainless steel is way stronger than aluminum, so the blades can be made thinner and more efficient. They don't flex under pressure, which means you get better grip in the water, better fuel economy, and usually a bit more top-end speed.
The downside? They cost three times as much, and if you hit something hard, that energy is going straight into your driveshaft. If you boat in deep, clear water, go stainless. If you're constantly dodging oyster bars or shallow river rocks, stick with aluminum and keep a spare in the hold.
Three Blades or Four?
Most people stick with a three-blade prop, and for a good reason—it's the best all-around performer for speed and efficiency. It's what the Yamaha 115 was designed to run most of the time.
However, don't sleep on the four-blade options. If you find that your boat struggles to stay on plane at lower speeds, or if you feel like the back of the boat is "squatting" too much, a four-blade might be the answer. Four blades provide more surface area, which gives you better "lift" and more control when docking. You'll probably lose 2 or 3 MPH at the top end, but for many family boaters or offshore fishermen, that trade-off is worth the extra stability and smoother ride in rough water.
Matching the Prop to Your Boat Type
The "perfect" propeller for Yamaha 115 outboard use depends entirely on what kind of boat you're driving. A 115hp engine on a lightweight 17-foot aluminum fishing boat needs a completely different setup than a 115hp on a 22-foot pontoon.
Pontoon Boats
Pontoons are essentially big wind sails that sit on top of the water. They have a lot of drag. For a Yamaha 115 on a pontoon, you generally want a large diameter prop with a relatively low pitch (often a 13 or 15 pitch). Look for props specifically designed for "high thrust." These have wider blades that help push all that weight and keep you in control when the wind picks up.
Bass Boats and Light Skiffs
If you're running a light fiberglass or aluminum rig and you want to beat your buddies to the fishing hole, you can usually go with a higher pitch, like a 19. Since the boat is light, the engine doesn't have to work as hard to get it moving, allowing you to take advantage of that higher "gear" for better speed.
Center Consoles and Bay Boats
These are the most common homes for the Yamaha 115. Usually, a 17-pitch stainless steel prop is the "magic number" here. It provides a good balance of acceleration for getting over waves and enough speed to get home before the storm hits.
Signs You've Got the Wrong Propeller
It's pretty easy to tell if your current setup isn't working. If you push the throttle all the way down and the engine screams but the boat barely moves, you're likely "spinning out" or your pitch is way too low.
Conversely, if you pin the throttle and it takes forever for the RPMs to climb, and you can't get the engine above 4,800 RPM, your pitch is too high. You're overworking the motor, which can lead to carbon buildup and long-term engine damage.
Another thing to watch for is ventilation. This happens when air gets sucked into the prop blades, causing the engine to rev up and lose grip. If this happens every time you try to turn, you might have the engine mounted too high on the transom, or you might need a prop with more "cup"—that's the little curved lip on the edge of the blade that helps it grip the water.
Maintenance and Care
Once you find that perfect propeller for Yamaha 115 outboard performance, you've got to take care of it. I always tell people to pull their prop off at least twice a year. Why? Because fishing line is the silent killer of outboards. It gets tangled behind the prop, melts into the gearcase seal, and lets water into your oil.
While you have it off, grease the propeller shaft with a good marine-grade grease. There's nothing worse than needing to change a prop and finding out it's "cold-welded" to the shaft because of salt and corrosion.
Also, keep an eye on the hub kit. Most modern props use a plastic or rubber insert (the hub) that's designed to spin if you hit something. If you notice your engine revving but you aren't moving, you might have "spun a hub." It's a cheap fix, but it'll leave you stranded if you don't have a spare hub kit on board.
Final Thoughts
There isn't a single "best" propeller for Yamaha 115 outboard engines because everyone uses their boat differently. The goal is to find the one that lets your engine breathe in that 5,000–6,000 RPM range while carrying your typical load.
If you're unsure, talk to a local prop shop. Many of them have "try before you buy" programs where you can test a couple of different pitches to see what actually works on your specific hull. It's worth the extra effort. When you get the propping right, it feels like you've bought a brand-new boat—the steering is lighter, the ride is smoother, and that Yamaha 115 will purr like it's supposed to.