What if anything would I notice from 3 to 4 blade prop

[Dhadley]

Re: What if anything would I notice from 3 to 4 blade prop

some advise you need to drop a degree when you go three to four... read the Mercury prop selector site...

If we're talking pitch (measured in inches, not degrees) then that can be true sometimes. If we're talking about rake (measured in degrees) you still want a high rake prop for a Ranger regardless if it's a 3 or 4 blade prop. You have to compare the same style 3 and 4 blade prop. Rarely do they operate best at the same X dimension (engine height).

 

[KDAVID1]

Re: What if anything would I notice from 3 to 4 blade prop

yeah--talking pitch. Haven't look at my papers on the rake yet. So do you think staying with the same rake and pitch with a 4 blade would keep my same RPM and speed performance?

 

[Dhadley]

Re: What if anything would I notice from 3 to 4 blade prop

Don't be surprised if you cannot find specific info on rake angle. Anyway, we have found that with the older Rangers the Turbo Lightning to be the fastest. Older Rangers benifit from props with bow lift and Lightnings have a lot. As for a 4 blade - the right 4 blade for your hull design - you're still looking for something with bow lift like the Ultima 4 or perhaps the Fusion 4. Both have great acceleration, mid range carrying ability and very good lift. A comparison will depend a lot on which prop you're running now (brand, style and model).

 

[KDAVID1]

Re: What if anything would I notice from 3 to 4 blade prop

would staying with the same pitch be correct or going down 1==ie. if going with a 4 blade would I need to go down to keep the same RPM?

 

[Dhadley]

Re: What if anything would I notice from 3 to 4 blade prop

Like I mentioned, it all depends on what 25" prop you're running now in order to make that comparison on paper or in theory. Not all 25" props are created equal.

 

[KDAVID1]

Re: What if anything would I notice from 3 to 4 blade prop

ok--roger that. I'll find my paper on it to see what the exact prop I have

 

[KDAVID1]

Re: What if anything would I notice from 3 to 4 blade prop

well I'm screwed--the only thing the paper says on it is Pro-V 14 1/2 X 25P. It doesn't tell me the manufacture of the prop--My dad said it was a Merc but I don't think it is ( nothing on the merc site about Pro-V.

 

[Dhadley]

Re: What if anything would I notice from 3 to 4 blade prop

There is a Pro Series brand made by Yamaha.

 

[KDAVID1]

Re: What if anything would I notice from 3 to 4 blade prop

Well I had another snafu today---went out for the first time this morning by myself (I only weigh 155) no extra gear--water was glass--only ran 55mph--RPM (trimmed correctly) hit 6000!!! My GPS is goofed I think (on previous runs) but the 6000RPM is what is scaring me. Did some calcs online and it is saying to run a 27 or 28 pitch? This engine is only a 2.5L 150 so I am really at a loss--I should be runningaround 68mph at 5500RPM WOT--and at the proper trim and such--I don't seem to have a rooster tail--frankly I don't see how this motor is turning the 25p prop 6000rpm (and the prop is not coming out of the water? Oh--Dhadley--I greatly appreciate your posts on this--it seems it just keeps going and going but I do appreciate your input

 

[KDAVID1]

Re: What if anything would I notice from 3 to 4 blade prop

OK so I went out today (fixed GPS) ran 57.8mph at 5500 RPM--so all is well there--although I think i could trim up a bit more and get more RPM but the RPM's go up too much. so I now I have defined that the 25p 3 blade pro v (which I did verify was a Yam.) is working right. After running today what I would be looking for is a bit more speed and staying in my RPM--handling is pretty good.