Prop Size Question

[b_spill]

My fishing partner is looking into buying a new prop for his 96 Johnson Intruder 150. We aren't sure what pitch is on there now, but I believe we could move up a size. It planes out in no time and our top end isn't the best. What size would be best for more top end on this motor? Also, are there any recommended brands?

[Way2slow]

You are asking questions there are no one magic answer.

First, you need to know the motors max recommended RPM and how many RPM the motor is currently turning at WOT and the current prop size. You want a prop that lets the motor turn within 100-200 rpm of its max rated. 100 over is better than 200 less. Trying to go to a higher pitch prop than the motor can turn near max rpm can actually slow you down.

As for the best type of prop, that is determined by the hull. Some hulls like a prop with a lot of rake, some don't. Some do better with a three blade, others do better with a four.

Not knowing any more than you posted, would be like trying to tells you what golf club to play a shot and knowing nothing about where the ball is.

[b_spill]

I guess I will clarify, is there anyone with this motor that would have any advice on the best prop size and brand?

[Way2slow]

I guess I will clarify!  The motor is on a boat, it does not run down the lake by itself.  The size and design of the  boat is what determines the size and type prop for a given motor.   Unless, someone has a mighty fine crystal ball, it's impossible to answer your question without a lot more info.  GOOD LUCK.

 

I'm done.

[J Francho]

Look up "prop slip calculator" and capture the required data, and you'll have a better idea of what pitch will work. No one solution even works perfect for all, and setup (height and setback) can change things too.

[b_spill]

The boat is 19 1/2 Stratos.

[Hi Salenity]

That's a start, we now MUST have an accurate WOT RPM and the prop pitch that's on the he boat now. And is its 3-4 blade?

[Ski213]

This is repetitive i suppose but the hull that is being pushed is at least as important as the outboard that's pushing it.

There's a whole lot that factors in. You can't say that this or that prop is the way to go with 150 anymore than you can say 33x12.50 is the right tire size for any vehicle with a 350 in it. If that 350 is pushing a full size truck ok, but if it's in a Camaro its not gonna work out so well.

Man I'm in no way criticizing your question but one hull with that 150 will respond very differently than another hull with the same 150.

[Fishing Rhino]

And, it depends upon the weight and where it is (weight distribution) that a boat is carrying.

 

A boat can be run bare bones, or, it can be loaded down with gear.

 

Before changing props, since it currently gets up on plane in a flash, try moving weight back.  It may not get up on plane as quickly, but it may increase top end speed.

 

To reiterate, the motor should run at the recommended revolutions per minute at wide open throttle.

 

Boats are complicated creatures, and as such, are at best, compromises.  It's why bass boats have power trim and power jack plates to find the ideal combination for hull design and load.  Generally speaking, bass boats sacrifice ride and comfort for speed.  It's easy to make a fast boat that rides like a buckboard, think hydroplanes, or a comfortable boat that is a turtle when it comes to speed, but can mush through rough water.

[Way2slow]

He probably thinks we're a bunch of dumb**** because we can't tell him what prop his buddies 150 Johnson should run, and probably fed up and posted it another sight looking for the answer.

[Logan S]

Generally speaking, lower pitch props will get on plane faster but sacrifice top end....Higher pitch props are better on top end and sacrifice hole shot.  At the very least, in order to make a change you'll need to know what is actually on the motor in the first place.  

 

3-blade, 4-blade, venting, prop make/model, motor height, motor setback, weight distribution, and probably a bunch of other things all have a measurable impact on performance.  It's usually not a simple process, sorry to say.

 

Having said all that, if you want the simple shot in the dark answer...You should have him try a 24P Raker, but there's a good chance that's what he already has.  

[Way2slow]

There are a number of members on here very knowledgeable of how select the right prop, but a little more info than provided is needed. I would have a hard time seeing something like a Stratos 295 under powered with a 150, turning a 24" Raker.