Three Blade Prop

[mulliganmagic]

I have a question about going from a three blade prop to a four blade prop. We have a 17.5 ft Norris Craft Bass boat with a 1986 Mercury 150 hp XR2. Currently it has a 23p three blade Quicksilver prop on it and will turn 5800 rpm. We found a loner prop from a family member to try, but it is a 26p four blade prop. We've been wanting to try a four blade prop to see what kind of performance change it gives, but I was curious if this is too much pitch for that motor and will it make it lugg too much with that high of a pitch. Do we need to find a lower pitch four blade or would it hurt to try this prop and what kind of rpms should I expect to turn?

 

[69GlassparMan]

Re: Three Blade Prop

I hear those PROPULSE adjustable pitch 4 blade props are awesome. Dont know if it would be similiar to what you are proposing.

 

[Dhadley]

Re: Three Blade Prop

Since you didnt mention what brand the 4 blade is -- its hard to say. General rule of thumb is that a 4 blade will run at a much higher X dimension than a 3. Sounds like your pretty well dialed in with the 3. Stick the 4 on and see. But dont (mis)judge all 4 blade props by this one. Not all props are created equal.

 

[mulliganmagic]

Re: Three Blade Prop

I didn't happen to look and see what brand the four blade was (I don't have it here where I can look at it). But we'll stick it on there and see what it does.

 

[heybaylor]

Re: Three Blade Prop

my 86 XR2 wont spin a 25 pitch..i/e 5000 rpm is<br />max . let alone a 26 ...good way to waste your motor..<br />The 86 XR2 is a 2.....repeat..<br /> 2 liter motor<br />23 is about as far as ya should go ...5500-6000.<br />if you want to try a 4 blade ...dunno why ?....I would use a 22 pitch...

 

[bluewater19]

Re: Three Blade Prop

Heybaylor,<br />Don't you think the size, weight, and hull type of the <br />boat should figure into how much pitch a given motor will turn?

 

[danie]

Re: Three Blade Prop

Answer to heybalor's question, a four blader turns much smoother (less vibration) and bites better (less slip) and improves holeshot when compared to a same pitch 3 blader.<br />D

 

[heybaylor]

Re: Three Blade Prop

I believe "magics" boat turns a 23 3 blade at 5800<br />That IS the hull/weight of his boat ..<br /><br />His XR2 will not turn a 26 pitch 3 or four blade at proper rpm on that boat<br /><br />Also not to get into a contest , but a 4 blade is not smoother, nor does it "not slip as much as a 3 ..<br />It does have more friction , and to turn it the same rpm as a 3 requires a lessor pitch ..<br /><br />Ask a good prop guy about pitch /rake /cup and dont forget the size/shape of the vent holes.<br />and if it is over the hub , or through the hub exhaust<br />All these come into play as to fine tuning any given hull..<br />not just pitch of the prop.<br />hmm, if more is better , how come the "high five " is now a joke

 

[sangerwaker]

Re: Three Blade Prop

Excuse me....High Five a joke? Sounds like someone is "high". <br /><br />EDIT: Ok maybe I jumped the gun a little with my comments. The high five is an awesome prop for the right application. For heavy loads and pulling power, they cannot be beat IMO.

 

[LubeDude]

Re: Three Blade Prop

Just throw it on and see what it does. Its likely too much prop for you though.<br /><br />I am running a turbo four blade, 25P 14.25 on my 18' Bass Boat with a 2 liter 150, it runs around 60 MPH, and around 5,600 RPM. Best prop Ive ever tried. You can run the engine higher on the transom with a four blade

 

[lyra]

Re: Three Blade Prop

26 pitch 4 blades sounds like to much. You need to consider boat weight,engine height,max rpm(wot)and what you trying to get(top speed or heavy loads).

 

[danie]

Re: Three Blade Prop

heybaylor<br />You definitely missed out on some serious information along the way. You can check by means of the search facility about vibration, slip, bite (holeshot) etc regarding 3 and 4 bladers. Start with the topic "Props: 3 VS 4 Blades."<br />There is no question about a 4 blader being smoother than a two or three. I will try and obtain the links to the relevant topics and website and make a posting for your information as soon as possible. It makes very interesting reading material and contains information all boaters should know.<br />I also speak of experience from help by members of this forum like Dhadley.<br />D

 

[danie]

Re: Three Blade Prop

heybaylor<br />Information I promised is available in postings under "Outboard Non-repair Discussions; Information: Propeller types/design".<br />D

 

[heybaylor]

Re: Three Blade Prop

Damdan , I guess this is a gentlemens "agree to disagree" subject <br />I respectfully stand by my statement.