Outboard Propellar Pitch

[hammersley]

My son has a 2005 90 HP Optimax with a 3 blade 19:1 pitch propellar. He is getting an over rev code stored for exceeding the RPMS. The dealer said he should get a 4 bladed 20:1. They didn't have one.



He called a shop and they said they can change the pitch to 20:1 for only $20..... Does that sound right??????



Anybody have any experience with this sort of thing?



Also - where can one get a 4 Blade Propeller for that application at a good $$$$



2 questions... ... .

 

[guava]

My son has a 2005 90 HP Optimax with a 3 blade 19:1 pitch propellar. He is getting an over rev code stored for exceeding the RPMS. The dealer said he should get a 4 bladed 20:1. They didn't have one.



He called a shop and they said they can change the pitch to 20:1 for only $20..... Does that sound right??????



Anybody have any experience with this sort of thing?



Also - where can one get a 4 Blade Propeller for that application at a good $$$$



2 questions... ... .

Here is two links to try with pretty good info:

link one

link two



Somewhere on the net, and I think it was one of the major outboard motor manufacturers had a prop 'calculator' which determined the best prop for your given configuration. I can't find it now... .



To answer your first question... repitching the prop is pretty easy to do. Its just a matter of reshaping the prop by taking material away. A little is ok, eventually you make it significantly weaker.



In this case, changing the pitch probably isn't enough. You have the difference of an extra blade in the water is significant between the two...



Hope this helps

 

[HOBrian]

If he is going up in blade number he might be able to get more pitch like a 21".

 

[juicedcummins]

He needs to go to a 3 blade 21 pitch of the same diameter as the current prop.

If you go to a 4 blade the overall diameter will be a little less and the pitch will be along the same lines you are headed to 21 pitch.



Note: If you go the 4 blade route you will loose some top end speed even as much as 5mph but it will come on plain faster and in some boats they will corner better. These props are not for every one or every application. The so called prop charts are a waste of time and are nothing more than a reference. Make a deal with the shop you are buying the prop from and take all three props and return the ones that do not make the spec. Make sure you know the rated rpm of the engine and load the boat the same as normal when testing the props.

 

[mberry]

My son has a 2005 90 HP Optimax with a 3 blade 19:1 pitch propellar. He is getting an over rev code stored for exceeding the RPMS. The dealer said he should get a 4 bladed 20:1. They didn't have one.



He called a shop and they said they can change the pitch to 20:1 for only $20..... Does that sound right??????



Anybody have any experience with this sort of thing?



Also - where can one get a 4 Blade Propeller for that application at a good $$$$



2 questions... ... .

He can go a couple of routes here. 1st he can have the pitch changed by the shop for the $20. Even if 20" isn't enough and has it changed to 21" then he has only spent $40. Ususally cheaper than a new prop.



2nd. he can get the 4blade prop. 4 blade props usually go in even numbers i. e. 20", 22" etc... If he goes that route, have him start with the 20". Remember he's only running 90hp, not 900. Take small steps and he'll eventually get it right where he wants it.



He may also work out a deal with the prop shop to test out different props for free until he finds the one he likes the best. Good luck. There is no "one size fits all" when it come to getting the right prop.

 

[hammersley]

Thanks for the info.....

will tell you how things go... ... ... ... he had the prop repitched but obly ran it for 5 min - test will come this week.....

 

[Jumbo Jet]

I have a 3 blade SS prop that has been rebuilt three times. The first time it had a pitch change from 19" to 21". Second time it was changed to 22".



SS props eliminate and/or reduce prop cavitation on higher HP engines and/or heavier vessels.



Engine revved way too high with the 19" and would even pass the redline with the 21".



175 HP I/O Mercruiser.