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Prop pitch/type 175 merc 4 stroke
1998 ranger 461vs had an evinrude ficht 175 that hit 6000 rpm 70-72mph when new with 4 blade 25 pitch prop. Put on brand new merc 4 stroke 175 and at 60-61mph 6000 rpm with a 21 pitch 3 blade. What in world is going on? Ranger is 17’10”.
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I quickly ran the prop selctor for you and got this:
YOUR SETUP
- Boat type: Bass
- Usage: Top Speed/0 ft
- Engine Manufacturer:
Mercury - Engine Type: Outboard
- Engine Year: 2020
- Number of Engines: One
- Engine Family: ProXS
- Engine: 175hp V6 Pro XS
- Drive / Gear Case: Large OB 175-225 HP 1.85 Gear Ratio
DETAILS
- Calculated Pitch: 24.30
- Calculated Weight with engine(s): 2,483.10 lbs
- Calculated Engine RPM: 5,850
- Calculated Boat Speed: 65.71 mph
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Pmantle... thanks for taking the time to do that. Makes sense to me. It’s my dads boat and trying to help him out. Are a dealer?
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No lol, I am just a guy who loves to read about this stuff. I went through a rough time properly propping my last two boats, so I have read a LOT of boat set reviews.
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I don't think that 4 stroke will turn a prop that size they are sending out boats with 250's on them and 23" pros. If it's turning 6000 now and you put a 24" prop on it you'll lose 600 rpms down to 5400 and you want to be as close to 6000 as you can get. I don't know how PMantle ran that prop selector but I ran it with the info you gave and it says run a 21" prop at 5850 rpm's to get what you have now. You can try a 23" and see what happens but I don't think it's going to gain much. Borrow a larger prop from someone you know and try it.
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The Ranger above is a 1999 18'9"! NOT 17'10". Helping my dad out as his boat and info was incorrect. Anyway..not sure what that changes with the scenarios.....anyone willing to run numbers again?
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The size of the boat doesn't make any difference as far as what the motor is doing or will do with a different prop. If you have access to a different prop larger in pitch try it but I would try something smaller than a 24-25" that's why I said a 23" prop. I don't know why but the new 4 stroke don't seem to be able to turn the bigger wheels they want smaller props at high rpm's. When he ran it would the motor turn more rpm's if he gave it more throttle if it would then it needs a larger prop.
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One more thing that I just thought about you said when it was new it went 70 was that on a speedo because a GPS was just about unheard of in 1999.
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My R83 with the new 4 stroke Mercury gets is best performance with a 23p tempest. I did lose 3 to 4 mph but that’s expected when you drop on pitch.
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