# Yamaha F40 prop



## Salt (Mar 19, 2019)

What is your target WOT rpm for that engine? 
Keep in mind that your rpm’s will be affected by pitch and diameter, among other things. 

My basic understanding is this: Generally a 1” drop in pitch will increase rpm’s by approx. 200. Vice Versa if increasing pitch then rpm drops. Reducing prop diameter (by 1”?) will increase rpm’s by 400-500, and vice versa is true if increasing diameter then rpm drops. 
If you want to get more precise or solve for things like max speed, holeshot, handling, etc., then more info is needed on your boat, weight, type of fishing you do.


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## Tom_Salisbury (Apr 17, 2014)

NathanEvans said:


> What is your target WOT rpm for that engine?
> Keep in mind that your rpm’s will be affected by pitch and diameter, among other things.
> 
> My basic understanding is this: Generally a 1” drop in pitch will increase rpm’s by approx. 200. Vice Versa if increasing pitch then rpm drops. Reducing prop diameter (by 1”?) will increase rpm’s by 400-500, and vice versa is true if increasing diameter then rpm drops.
> If you want to get more precise or solve for things like max speed, holeshot, handling, etc., then more info is needed on your boat, weight, type of fishing you do.


 Thanks. I have the basic understanding of props. I'm trying to get the rpms up. I know top end speed will probably drop but hole shot improve.Just seeing if anyone had any opinions before I drop a couple hundred bucks.


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## mwolaver (Feb 6, 2014)

Tom_Salisbury said:


> I have a salt marsh skiff lowcountry with Yamaha 40. I have a Yamaha hot shot 12 pitch. I can get 5100-5300 rpms . Thinking about dropping to 10 pitch. Any recommendations? I tried powertech and wasn't happy. Thanks Tom


My F40 is on a 16' waterman (tiller). I am running a powertech 13 pitch prop and getting around 5500 rpms and 33 mph. I was really close to buying a 12 in a different (stern lifting) blade, but eventually got over it. Yes, it is best to get full rpm range (6100). But if your hole shot and top end are adequate, you can spend a bunch of money fiddling with props. My 2 cents


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