prop.

[DjGiese1995]

will a 141/8 x21 prop. get me up on plane faster than a 14 3/4 x15

[ESOX]

No if anything it would be much slower to plane. That is a huge difference in prop sizes one of them has to be just plain wrong for the application.

[DjGiese1995]

does lower number pitch mean faster plane say 14x15 or14x11 have 14x15 now boat came with13 1/4 x17 went with 14 3/4 x15 need to replace again

[Big Frank 25]

Look here http://www.turningpointpropellers.com/default.php

[waterfoul]

Lower pitch does not always mean faster to plane.... it can mean faster to blow up your motor. You want to pitch your motor to run up to it's top RPM with a normal load onboard... if you under pitch your boat you might get on plane faster but you will go slower and over rev your motor.

I've played with a lot of props on a lot of boats and there is no true science to picking the correct prop. Testing them is the only way to be sure a prop does what you need it to.

[just ducky]

Okay, somebody help an idiot understand please :evilsmile

First off, let me say that speed really isn't my concern. Normally my boat is used for duck hunting, pushing a lot of weight, so slower and steadier is fine. But once in a while in the summer, we get the kids out on a tube, so as much speed as possible would be nice. I have a 50hp Merc 2 stroke, haven't gauged it but the specs are the WOT is 5500. I currently have a 13 pitch prop on it, which I think works fine. Through reading LOTS of posts about props on various websites, I guess I've learned that generally lowering the pitch will increase speed...maybe :lol: So I've done some research on my engine and Merc. has several suggested props, and for top speed I believe they recommend one with an 11 pitch. My question is this...with a 50hp outboard, how much addtional speed am I realistically possibly going to get dropping the pitch by 2? Is it worth getting another prop (I have two already :dizzy:). I can see it having an impact with a larger outboard, but with a 50??? I just can't imagine there will be that much difference with a 50hp.

[Priority1]

By droping from a 13 to 11 pitch same dia prop, you will probably gain about 400 rpm WOT. The pitch thing is not an exact science. The boats weight and load enters into the equation. You may loose 2-5 MPH. Your best bet is to use an accurate tach while checking WOT and go to a prop that will give you the WOT RPM. Dash tachs are actually a poor way to judge WOT RPM. Dash tachs can be off by as much as 10%. 10% can be critical.

Generally speaking you will gain or loose about 200 RPM for every inch of pitch change.:)

Think of a prop like this: a thirteen Pitch prop will move the boat through the water 13 inches for every turn of the prop. Granted this never happens due to friction etc.

[waterfoul]

Going from a 13 pitch to an 11 pitch prop will do two things:

1) You will go slower
2) You will blow up your motor.


And in that order.

[just ducky]

Going from a 13 pitch to an 11 pitch prop will do two things:

1) You will go slower
2) You will blow up your motor.


And in that order.

If that's the case, why would Mercury recommend it for this particular motor? Now I'm really confused. But I know one thing...I'm gonna leave well enough alone.

[waterfoul]

If you are HEAVY, and I mean loaded up that smaller pitch prop might be o.k. BUT, do you want to take the chance of over-revving the motor, especially since you don't have a tach? I would simply leave well enough alone.

[Big Frank 25]

I've a Mirocraft Big Lake Fisherman bare bone, 1500lbs! With my 1977 Merc I ran 15" and 17" props. With the new Merc I'm running a 15" prop that runs 31 mph (gps) @ 5100 rpm.

[just ducky]

I've a Mirocraft Big Lake Fisherman bare bone, 1500lbs! With my 1977 Merc I ran 15" and 17" props. With the new Merc I'm running a 15" prop that runs 31 mph (gps) @ 5100 rpm.

Frank,

What size Merc is that? Seems as if I clocked my 17' Alaskan with 50hp Merc in the high 20's with the GPS last year. Honestly can't remember exactly. All I know is it gets out of it's own way real well. And good enough to pull an adult on a tube across Houghton Lake really well :lol:

[Big Frank 25]

I stuck with a 50.