Need help with Prop Choice

Dacar92

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Oct 11, 2010
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Hi guys,

I have a 24' 2000 Manitou pontoon with a 90 HP Johnson outboard. I need to get a new prop but there is nothing on the prop to indicate the pitch. It is a 3 bladed prop and the only stamped numbers or letters on it are D52B. That's it. Is there a standard used for pontoons and 90 HP outboards?

I pull kids on tubes, other than that it is just a cruiser.


Thanks in advance.
 

Dacar92

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Re: Need help with Prop Choice

For some reason, my edit to the OP will not submit.


EDIT:

I found a couple other stamped items. On the inner hub there are two set of numbers:

391668

&

14 X 13
 

Dacar92

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Oct 11, 2010
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Re: Need help with Prop Choice

I assume that one is an OEM part number
391668

and the other is the diameter and pitch. Is my thinking correct?

Thanks
 

jestor68

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Jun 12, 2012
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2,308
Re: Need help with Prop Choice

I assume that one is an OEM part number
391668

and the other is the diameter and pitch. Is my thinking correct?

Thanks

Yes. The 14 X 13 is the diameter and pitch.

What WOT rpm does the motor achieve using that prop?
 

Dacar92

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Re: Need help with Prop Choice

Yes. The 14 X 13 is the diameter and pitch.

What WOT rpm does the motor achieve using that prop?

Hi. Thanks for the reply. I have no idea about that answer. The boat does not have an RPM meter. Plus, it's winterized and the prop is at my house. Not on the boat.

Are you asking to help optimize my prop choice? If so, thank you. However it seems I have no choice but to replace it with the same type.

Would one of these be the right choice?

13” Pitch Evinrude Outboard Boat Propellers 90 HP 1981 & Newer - iboats

Thanks
 

jestor68

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Re: Need help with Prop Choice

For what it is worth, I had a 24 ft pontoon boat with a 90 HP Mercury motor.

It turned a 15" pitch Solas aluminum prop at 5400 WOT rpm.
 

steelespike

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Joined
Apr 26, 2002
Messages
19,069
Re: Need help with Prop Choice

A 13" prop is a reasonable selection.
it is important for best performance and the health of your motor to have a tach.
Also good to have a gps for speed. your motors wot rpm range is 5250-5750.
The motor should be propped to operate within that range at wot, even if you mostly only cruise.
 

Dacar92

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Re: Need help with Prop Choice

A 13" prop is a reasonable selection.
it is important for best performance and the health of your motor to have a tach.
Also good to have a gps for speed. your motors wot rpm range is 5250-5750.
The motor should be propped to operate within that range at wot, even if you mostly only cruise.

Thanks very much for that info. I can install a tach next year in the Spring. I'll have to get a 13" this winter and I will monitor the WOT during the summer. Go for this one?

Solas Amita Aluminum Boat Propeller #2411-138-13 for Evinrude 90 HP Outboard 1981 & Newer - iboats

Whats the difference between that one and this one? Besides the little bit of diameter? Will I notie any performance difference at all?

http://boatpropellers.iboats.com/Ev...-138-13_Propeller/86/20288/?*******=608717241
 

steelespike

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Apr 26, 2002
Messages
19,069
Re: Need help with Prop Choice

These are esentially the same prop.
The Rubex has a separate hub. If there was a bigger difference in diameter I would go for the larger on a pontoon.
A few months ago there was a discussion here regarding the hub getting stuck in the prop
making it sometimes a difficult for in the field replacement when changing for water sports etc.
I guess if you were inclined to want to fiddle with different props you might be able to try a Merc Rubex prop on your Johnson.
And of course if you wanted 2 or 3 props for specific use you might be able to save a little.
 

jestor68

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Re: Need help with Prop Choice

Mercury calls there's Flow Torque. Solas is Rubex. Michigan is Vortex.

And yes, I assumed that you were interested in optimizing the performance of your boat.

Since you cannot know if the prop that happened to be on there is the correct one, a tachometer needs to be used to determine the correct one.

I suggest you pay a visit to a local marine dealer and request their assistance in determining the correct prop. They should agree to go with you, using their shop tach to select the best prop; provided you purchase the prop from them.

As a retired marine service manager, I have done this numerous times for our customers. You'd be surprised how many times that the prop that came on a boat was not the best choice.

Your target rpm range is 4500-5500 rpm for a 2000 Johnson 90.
 
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