What prop do I have?

papasmurf79

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Oct 2, 2017
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Im very new to boat ownership so I apologize if my question doesn't come out right. Recently bought a 1982 Infinity Del-Magic. It has a 1982,115 Merc outboard. It seems like the motor has to work to hard to get the boat moving. I tried finding markings onn the prop to see what we had but can not find anything. I thought it would be marked on it somewhere. Its an aluminum three blade. Is there someplace else I can look to try and find out what the prop is? Thanks for your help.
 

ondarvr

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Apr 6, 2005
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Sometimes you need to take the prop off to find the numbers.
 

papasmurf79

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Oct 2, 2017
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Ok I pulled the prop off and found the part #48-77344-17
I believe from what I can find its a 13.25x17 then. Now my next question would be, How do I figure out if its right for what we have. The boat is 17 foot and weighs about 1200 I believe. I would like to be able to have a few people in the boat and pull a tube without issue. Im also in colorado so we are at 5000 ft up here.
 

ondarvr

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Apr 6, 2005
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You need a tachometer and and gps for speed, plus know the RPM range for your motor.
 

jimmbo

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May 24, 2004
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An 82 115hp would have a WOT range of 5000 - 5500 rpm. I doubt, at a 5000ft altitude you are getting this with a 17. You might have to drop down to a 15" or even a 13" to get the rpms into the 5000 - 5500 range. As propeller efficiency drops as the pitch goes down, a better choice would be a gearcase with a 2.3:1 ratio instead of the standard 2:1. The engine is also running rich due to the altitude, but jetting it leaner might not be an options as I have never seen a chart for that year of engine. You are certain it is an 82? there were many differences between the 81 and earlier engines and 82 and later engines
 

papasmurf79

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Oct 2, 2017
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Thank you for your responses. The serial number on the motor is 6052035. From what Im finding, yes its an 82.
 

racerone

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Dec 28, 2013
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Step # 1 is to determine the condition of the motor.-------Changing props to get the rpm you need may not be the proper approach.----What if low compression is the problem ?---What if carburetors are partially plugged ?
 

papasmurf79

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Oct 2, 2017
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Thank you very much. We are going to look at a few more things and try to get some numbers for comparison. Think we might actually have a bad prop bushing?
 
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