I have a 1989 40 hp evinrude. today I broke the prop on a rock and need some help figuring out what kind and style to get for a new one and where I can get one. It had an aluminum 11-3/4 x 17. With this prop I couldnt run the motor at full throttle because it would hit the rev limiter so I would like to put a 19 pitch prop on it. I dont have much knowledge of props and motors so Im not sure how to go about buying a new one and what I need to know before I buy one. I run this boat mostly on a shallow river so the last guy that worked on my motor told me an aluminum prop would be better for that so it would break or bend if it hit something. any advise would be helpfull. Thanks.
I need help chosing a prop for my evinrude.
CedarRiverSlayer
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I have a 1989 40 hp evinrude. today I broke the prop on a rock and need some help figuring out what kind and style to get for a new one and where I can get one. It had an aluminum 11-3/4 x 17. With this prop I couldnt run the motor at full throttle because it would hit the rev limiter so I would like to put a 19 pitch prop on it. I dont have much knowledge of props and motors so Im not sure how to go about buying a new one and what I need to know before I buy one. I run this boat mostly on a shallow river so the last guy that worked on my motor told me an aluminum prop would be better for that so it would break or bend if it hit something. any advise would be helpfull. Thanks.
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where ya from there is a cedar river in Iowa. I just bought the same motor and I am not sure what prop I have on there so I cant be of much help Mine is SS so I look forward to what you hear for suggestions because I need to go to an aluminum one as well.
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Im in northern Iowa by Mason City.
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Last prop I bought came from Dan's discount props website. They have a prop wizzard that can help you choose based on your particular motor, boat, weight load etc. According to the site going up in pitch like you stated should drop your RPM's about 400.
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You don't want to be hitting your rev limiter (actually I didn't know it had one). Increasing pitch will lower your RPMs (the 400 sounds about right), it will also increase the time to get on plane. However, with a 40hp that probably isn't a big issue. If you are reaching a rev limiter, you are loosing top end. The prop wizard software may be the best bet, but going up 2" will only help.
As far as SS vs Aluminum.... that's a personal selection. A SS is more efficient. A SS is also more durable, but damage may be transmitted to your lower unit instead of the prop. An aluminum prop is cheaper and less likely to damage the lower unit upon impact with an obstruction. However, a damaged aluminum prop that is continually run can induce damage over time to the lower unit due to the imbalance. Your choice!!!
All my blah blah blah really didn't help any... did it? :cf:
As far as SS vs Aluminum.... that's a personal selection. A SS is more efficient. A SS is also more durable, but damage may be transmitted to your lower unit instead of the prop. An aluminum prop is cheaper and less likely to damage the lower unit upon impact with an obstruction. However, a damaged aluminum prop that is continually run can induce damage over time to the lower unit due to the imbalance. Your choice!!!
All my blah blah blah really didn't help any... did it? :cf:
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what does the 11-3/4 mean on the prop? is that the diameter? When I buy a new prop does it have to be the same diameter?
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Diameter
Diameter is two times the distance from the center of the hub to the tip of the blade. It can also be looked at as the distance across the circle that the propeller would make when rotating. It is the first number listed when describing a propeller.
Unless you have clearance for a bigger diameter....yes you should stay with what you have
Diameter is two times the distance from the center of the hub to the tip of the blade. It can also be looked at as the distance across the circle that the propeller would make when rotating. It is the first number listed when describing a propeller.
Unless you have clearance for a bigger diameter....yes you should stay with what you have
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I just don't see that little 40hp motor turning a 19'' pitch prop. I think its gonna be too much if you have any weight in the boat at all.
The 11 3/4'' is the prop diameter. It may change when you chance pitch. As long as the diameter is close to the same, you will be fine.
The 11 3/4'' is the prop diameter. It may change when you chance pitch. As long as the diameter is close to the same, you will be fine.
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Tips on selecting the right boat propeller
When choosing a boat propeller, in order to achieve the best performance, you should first find out what your recommended wide open throttle (W.O.T.) R.P.M. operating range is for your engine. This will be in your engine owner's manual, if you don’t have a manual, call a local boat dealer who services your brand of engine and ask them what the W.O.T. range is. We might also know too, but not in all cases.
Usually in the W.O.T. range there ia a 400 to 1000 rpm difference between the lower number and the higher number. If you have the right propeller on your boat you should be in this range (preferably nearer the higher number) while going full speed and fully trimmed up if you have power trim.
Boats without tachometers are harder to prop right but if you can at least get the numbers of your old boat propeller that would help us greatly. (see bellow)
The next thing you should know is what size propeller you have on your boat right now and what your R.P.M.'s are doing with it at full speed and full trim.
Boat propellers come in different sizes. There will be some numbers stamped around the prop shaft hole (on the propeller) on the end where the prop nut goes on.
They also might be stamped in between the blades on the barrel part of the propeller.
These will be a part number and/or the actual size number. Either way we can determine what you have and go from there.
There are always two size numbers for any boat propeller.
The first number is the diameter (measured from the prop shaft hole out to one blade tip times two).
The second number is the pitch (how far a propeller should travel forward through a solid one revolution in terms of inches).
The pitch is the most important number because different pitches will make the engine R.P.M.'s change at full speed.
The theory is for every one inch in pitch the RPM's will change 150 to 200. The higher the number pitch means lower R.P.M.'s, and the lower the number pitch means higher RPM's.
So the quest is to get the right pitched prop that will get you in your recommended W.O.T. R.P.M. operating range.
When choosing a boat propeller, in order to achieve the best performance, you should first find out what your recommended wide open throttle (W.O.T.) R.P.M. operating range is for your engine. This will be in your engine owner's manual, if you don’t have a manual, call a local boat dealer who services your brand of engine and ask them what the W.O.T. range is. We might also know too, but not in all cases.
Usually in the W.O.T. range there ia a 400 to 1000 rpm difference between the lower number and the higher number. If you have the right propeller on your boat you should be in this range (preferably nearer the higher number) while going full speed and fully trimmed up if you have power trim.
Boats without tachometers are harder to prop right but if you can at least get the numbers of your old boat propeller that would help us greatly. (see bellow)
The next thing you should know is what size propeller you have on your boat right now and what your R.P.M.'s are doing with it at full speed and full trim.
Boat propellers come in different sizes. There will be some numbers stamped around the prop shaft hole (on the propeller) on the end where the prop nut goes on.
They also might be stamped in between the blades on the barrel part of the propeller.
These will be a part number and/or the actual size number. Either way we can determine what you have and go from there.
There are always two size numbers for any boat propeller.
The first number is the diameter (measured from the prop shaft hole out to one blade tip times two).
The second number is the pitch (how far a propeller should travel forward through a solid one revolution in terms of inches).
The pitch is the most important number because different pitches will make the engine R.P.M.'s change at full speed.
The theory is for every one inch in pitch the RPM's will change 150 to 200. The higher the number pitch means lower R.P.M.'s, and the lower the number pitch means higher RPM's.
So the quest is to get the right pitched prop that will get you in your recommended W.O.T. R.P.M. operating range.
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19 does seem high for a 40hp. We have a 48hp johnson on or boat. It had a 17p on it but had problems planning out when loaded with fish. We actually dropped to a 13p, got better hole shots and are able to run faster when loaded down. Of course everything will vary depending on boat size and weight. We stayed with aluminum because most of the lakes we fish are stumpy and I would rather pay $30 bucks to have one reworked than tear up something in the lower unit.
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I think a 19 pitch would be about perfect on it. do I need to know the size of the shaft or anything specific like that? or do I just find a 11-3/4 X 19 prop for a 40 hp evinrude and it should fit?
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I put all the specs into the prop wizard and it still recomended the same 11-3/4x17 prop that I already have on it. With the 17 pitch prop my 16 footer was on plane in no time at all and was easily bouncing off the top end of the engine range. I had to run it at about 85% of the throttle so it wouldnt.
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nope no tilt or trim, it would be nice though.
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JpEater is right.... 19"pitch is huge for a 40hp. My father has a Bass Tracker TX17 with a 40hp... used just for fishing. All he can turn is a 13" pitch SS prop... and no where near over revving it. It doesn't jump out of the hole either. Anything bigger wouldn't work.
Of course the lower unit gear ratio makes a big difference, so all 40's aren't the same, but I don't think most 40hp outboards are designed for high pitch props.... maybe yours is diff. :cf:
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Im still stumped on this one. when I got the boat it had a 13 pitch prop on it and it was over reving at about 60-70% of the throttle. I jumped it up to a 17 and it helped alot but still does over revs right at the top end. I.ve been looking for a 19 pitch but cant even find one for my motor.
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