I need help for prop size
 

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

If everything is as it should be with the boat/motor setup the 17 should turn up a little too high and the 21 too low.
Try the 19 and see how it performs.

Most guys with a 150 horse do real good with a 17 pitch, some with a 15 and a couple with a 19.

try the 19 first, you want it to turn around 5500 at WOT

What do you mean by "good for your boat"? If you mean what is the best prop for your engine, then the answer is whichever prop lets your engine turn at 5500 RPMs with the throttle wide open is the best for your boat.

It's hard to guess accurately what prop that would be since there are so many things that can effect your final speed. Amount of fuel, number of persons on the boat, food, bait, tackle, anything that adds weight will effect your top end speed. Additionally, if your hull is smooth or rough will effect it also, plus how you have your engine trimmed... All these things can and will have an effect.

As both Spareparts and Tsubaki have already said, try the 19 Pitch prop first. If your engine RPM is right around 5500 rpm then it probably is the best one for your boat. Only you can make that determination after trying it though.

Most run a 17. If you don't carry any additional weight and want to have more top end speed run a 19, but it won't plane off as quickly.

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...

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) :head:

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

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

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