[Noslo5oh]

I have a 1996 240 with a 502 mpi and needing some assistance with the best prop for the job. The boat came with a 13" 23P SS prop but had a tore up aluminum 15" 23P proip in the boat when i purchased it. it seems at higher speeds the prop tends to free spin. just looking to know if anyone might know the factory prop size that this boat would have came with and what would be the best size prop for mid range and top end performance..

[mikeyt]

The boat likely came with the 15" - 23p aluminum prop. How does the boat perform with the existing prop? What is your WOT rpms and top speed?

If you want, Mercury has an online Prop selector which guides you thru the steps to selecting a prop for your boat. You can check that out here.

[Motoxxx43]

There are a few factors to consider when picking your prop. As for the stock setup I can't help you. I will say that with your particular setup the 15" prop is the way to go. I'd highly recommend getting stainless too.. What pitch? Depends on how many blades you run. I have a Shabah 250 with a 7.4 mpi. She's heavy. I run a 15"x19p Mirage. The Mirage has become my new favorite prop even though its only 3 blades. I have a 4 blade on the SC21 we use to ski with.

[Noslo5oh]

What kind of speeds and RPM's are you seeing with the 15" 19P prop?

Mikey, with the 13" 23P SS it will go up to 60mph but at 4000 RPM's and try to give it throttle it goes into a free rev.

[Motoxxx43]

Originally Posted by Noslo5oh

What kind of speeds and RPM's are you seeing with the 15" 19P prop?

Mikey, with the 13" 23P SS it will go up to 60mph but at 4000 RPM's and try to give it throttle it goes into a free rev.

Speeds will differ between us. I'm at 5000' elevation. I can hit 46-48 GPS depending on load. It runs 4600 at WOT. I put a 23p mirage on there an it was a dog. I had a similar top speed but at 4100 rpm. I could tell the motor did not like that pitch at my elevation.

Sent from my DROID RAZR HD using Tapatalk 2

[mikeyt]

4000 rpm at WOT is too low for that engine. You need to be up around 4600-4800. I also think that a 13" dia prop is too small (should be around 14.25" to 15") for that motor so, all that said i would recommend a 20" - 4 bade or a 21" - 3 blade in SS. You could go as low as a 19" - 3 blade and really increase your low end acceleration but it means your top end will suffer somewhat more than you likely want. You have to understand that everything with props is a trade off. Its either max low end - mid range grunt or max mid range acceleration - max top speed and the points in between those two extremes. I've yet to see a prop that achieves everything. And as Motoxxx43 notes, elevation changes things.

[Andy b]

Originally Posted by mikeyt

You have to understand that everything with props is a trade off. Its either max low end - mid range grunt or max mid range acceleration - max top speed and the points in between those two extremes.
I've yet to see a prop that achieves everything.

how deep are your pockets then mikey

The Power Pitch® Pro

[Motoxxx43]

Hey Andy my boat buddy bought one of those last season(possibly the exact brand). It was a 19p to a 21p. It did exactly like the description says. He used it for one weekend an sent it back. It shifts hard. I'm talking like neutral drop hard. And that's on both acceleration and deceleration. He didn't see that being good on the out drive/motor. When the boat was loaded it still did not like the 21p top end. Just food for thought if you were considering.
Ingenious idea though. You can adjust when it shifts too. Pretty gnarly till you get caught between shift points and hitting a wave down shifts and quickly upshifts again.
Sent from my DROID RAZR HD using Tapatalk 2

[Andy b]

A friend over here has one on a 3.0L and loves it. Maybe they don't like the power.
It's still new tech and i'm sure there will be many improvements.
We will see more of this type of thing in the next few years i'm sure.

One thing I will say is he's terrified that he'll ding it!

[mikeyt]

Originally Posted by Motoxxx43

Hey Andy my boat buddy bought one of those last season(possibly the exact brand). It was a 19p to a 21p. It did exactly like the description says. He used it for one weekend an sent it back. It shifts hard. I'm talking like neutral drop hard. And that's on both acceleration and deceleration. He didn't see that being good on the out drive/motor. When the boat was loaded it still did not like the 21p top end. Just food for thought if you were considering.
Ingenious idea though. You can adjust when it shifts too. Pretty gnarly till you get caught between shift points and hitting a wave down shifts and quickly upshifts again.
Sent from my DROID RAZR HD using Tapatalk 2

I've heard the same stuff about that prop from various sources. Until they get one that shifts as smooth as a car automatic transmission, it can stay on the store shelf.