1801 115HP Prop size
- Thread starter rileykate
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Many factors on why each boat would be faster. Are you talking Top Speed? Hole shot? 2 / 4 stroke? Carb/FI? Bottom condition?
I've run the Yamaha
17p SS
17p Alum
19p Alum
I've run the Yamaha
17p SS
17p Alum
19p Alum
CobbFisherman
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The 1801s at my local dealer all come with a 13'' diameter x 19 pitch prop. Based on my experience with a 115 E-tec on my 1800, I think that's too little diameter and too much pitch, although I have never ridden in a late model 1801 with the stock Yamaha and factory prop.
Knowing just the pitch isn't useful. Props are listed as diameter and pitch. I have a 14.8'' diameter x 17 pitch 3 blade aluminum prop on my E-tec 115 on an 1800. I'm getting 36 mph at 5500 RPM at WOT with a loaded down boat. I think its slightly over propped, and would probably drop down to either a 14'' diameter x 17 pitch or a 14.8-15'' diameter x16 pitch prop.
They say that for every 1 pitch you drop you gain 500 RPM at WOT and for every inch of diameter you drop you gain ~300 RPM at WOT. These are definitely generic estimations, but I've found them to be generally true.
Lower pitch will give you better hole shot and higher WOT RPMs but a lower top speed. Smaller diameter will spin up faster and have a higher WOT RPM, but smaller diameter will also 'slip' more. Bigger diameter gets better traction and reduces slip, at the cost of reducing WOT RPMs. Too much slip will kill your efficiency and gas mileage. Its all a balance.
Blade shape is also a big factor. Some of the higher speed props have less blade surface area, which will give you higher WOT RPMs than a prop with the same diameter and pitch specs with a bigger blade area. For general discussion, I think we can assume that we're not talking about fancy performance shape props though.
Based on some articles comparing outboards, I think the 115 E-tec makes almost 10 more horsepower than a 115 Yamaha, which might help me get away with a slightly bigger/steeper prop compared to what you guys are running on the Yamahas.
Knowing just the pitch isn't useful. Props are listed as diameter and pitch. I have a 14.8'' diameter x 17 pitch 3 blade aluminum prop on my E-tec 115 on an 1800. I'm getting 36 mph at 5500 RPM at WOT with a loaded down boat. I think its slightly over propped, and would probably drop down to either a 14'' diameter x 17 pitch or a 14.8-15'' diameter x16 pitch prop.
They say that for every 1 pitch you drop you gain 500 RPM at WOT and for every inch of diameter you drop you gain ~300 RPM at WOT. These are definitely generic estimations, but I've found them to be generally true.
Lower pitch will give you better hole shot and higher WOT RPMs but a lower top speed. Smaller diameter will spin up faster and have a higher WOT RPM, but smaller diameter will also 'slip' more. Bigger diameter gets better traction and reduces slip, at the cost of reducing WOT RPMs. Too much slip will kill your efficiency and gas mileage. Its all a balance.
Blade shape is also a big factor. Some of the higher speed props have less blade surface area, which will give you higher WOT RPMs than a prop with the same diameter and pitch specs with a bigger blade area. For general discussion, I think we can assume that we're not talking about fancy performance shape props though.
Based on some articles comparing outboards, I think the 115 E-tec makes almost 10 more horsepower than a 115 Yamaha, which might help me get away with a slightly bigger/steeper prop compared to what you guys are running on the Yamahas.
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Forgot that part
Yamaha-K 3 blade SS 13.25"
The 17P is my favorite for all around.
40mph @ 5700rpm in the flats
Yamaha-K 3 blade SS 13.25"
The 17P is my favorite for all around.
40mph @ 5700rpm in the flats
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This is all great information. I will be out on the boat next week and will note the rpm, speed and what prop is on the engine. My pick-up and the curse is comfortable. Its just slower than the 2005 I had. Fuel burn is great! It has a 40 gallon tank and I never put over 20 gallons in the tank. The 115 sips fuel all day long. I will post my findings next week If anyone is interested the boat can be purchased for a fair price. The boat that I have sells new for just under 60k with a trailer. I will take 35k. Boat is mint and never been fished. I poke around Palm Beach Inlet enjoying the water and sun. Thanks
