I need help for prop size

[reelapeelin]

Originally Posted by Shubbar

Hello every one i have wellcraft V20 step lift and Johnson 175 Ocean Runner 1995 Counter-rotating and i have 3 size prop 17 19 and 21
what is the best prop i can used to my engine i need speed and good for my boat engine
thank you

Those were the same 3 choices available to me when setting up my 1st 200HP on my present '84 V20...and you are right between my present and past motors re HP!!......BOTH 150s I had performed their best w/17s...the Honda spun up to 6 grand w/a 17...perfect for THAT motor...my 200, I'm still not sure about, but indications are the 19 will be the pick...haven't actually run the 17, but will before final decision...I'm thinking the 19 for yours since the 175's redline is 55...you want to test that under best possible conditions...flat water, no wind, light load(not the trip for all your buddies and their beer...lol!!), low fuel, top down and motor trimmed out as far as possible and still getting FULL BITE...if under that condition, she redlines @ WOT, then THAT'S yer prop...let us know how it comes out...

[Destroyer]

Originally Posted by reelapeelin

...my 200, I'm still not sure about, but indications are the 19 will be the pick.....

Reel, I run a 19Pss on both my Cruisers 200 Merc and my Wellcraft 200 Johnnyrude. Seems like the proper prop for a 200 engine.. I know a lot of different things make the final determination, but I'm willing to bet that you'll settle on the 19 (or maybe a 21 if you go Alum)

[reelapeelin]

Originally Posted by Destroyer

Reel, I'm willing to bet that you'll settle on the 19

I'd make the same bet, but w/a 17 sittin' there staring at me, I gotta at least give it a try...

[randlemanboater]

Shubbar, are all 3 props you have 15 inch diameter?

I beleive all the replys so far are assuming that they are 15" diameter.

[Shubbar]

hi now i don't know what prop i used i need speed and low RPM

[Destroyer]

Originally Posted by Shubbar

hi now i don't know what prop i used i need speed and low RPM

NO, you need speed and whatever the RPM is that your engine maker says you need. The higher the RPM, the higher the speed. Your engine maker will give you a figure for a point where your engine is most comfortable running. That figure is expressed as WOT or Wide Open Throttle. Typically, that will be around 5500 rpms for a 2 stroke engine. That is the speed that your engine is most comfortable at.

[Shubbar]

Thanks alot for all replay now if the RPM is 5500 that mean is good prop ??

[Destroyer]

Originally Posted by reelapeelin

I'd make the same bet, but w/a 17 sittin' there staring at me, I gotta at least give it a try...

LOL... I'd do the same thing... Never let a chance to experiment go to waste...