Prop Talk Vol: 12548662548

[Waffles]

Inmates please help me understand what to look for when choosing a different prop. Mind you, Ive had my 25' pontoon for 2 seasons now and have never worried about knowing if im running the correct prop because im a "if it aint broke, dont fix it" kinda guy until the last couple of trips when it started "slipping" going up against the current(first prop boat so im assuming this is what cavitation is). I used mercs prop selector tool and it kind of threw me off with the results it came up with when choosing the "overall performance option".

25' pontoon running the inline 4 3.0 with alpha 1 drive

Currently running this prop and it gps's 18 max @ 4200rpms

http://www.boatpropellerwarehouse.c...-max-16-x-14-mercury-rh-propeller-48-16438a45

Merc is suggesting i run a 16' 12 or 13 pitch prop with pontoon cupping?

http://www.boatpropellerwarehouse.c...toon-16-x-13-mercury-rh-propeller-48-78114cp1
http://www.boatpropellerwarehouse.c...toon-16-x-12-mercury-rh-propeller-48-16436cp1


or a 15.3" w/ 14p

http://www.boatpropellerwarehouse.c...a-15-3-x-14-mercury-rh-propeller-48-898988a46

Am i running the wrong prop?

 

[HavaToon]

Enertia is the best all around prop for a pontoon, but is typically used on higher HP than you have. Usually 250hp+.

The smaller diameter and more pitch of the enertia will give you better midrange and top end. While the larger diameter and lower pitch of the Black Max will give you better low speed control/reverse and load carrying (people).

So it really depends on how you boat. I'd suggest trying both and comparing to your current prop. Pick your favorite to your style of boating.

 

[outboardrick]

Pontoons are fairly hard to prop because you will never see enough speed to "feed" the prop correctly and it will cavitate under full throttle. A small pitch with LOTS of cup is usually the best way to go. Be sure you are able to get close to your WOT rpm area so you don't overload the motor.

 

[fishing fool]

If you are thinking that the prop is slipping going down on pitch will make it slip more.
With your current prop gps speed and rpm is that WOT? What is your max rpm?

 

[Waffles]

If you are thinking that the prop is slipping going down on pitch will make it slip more.
With your current prop gps speed and rpm is that WOT? What is your max rpm?

Pontoons are fairly hard to prop because you will never see enough speed to "feed" the prop correctly and it will cavitate under full throttle. A small pitch with LOTS of cup is usually the best way to go. Be sure you are able to get close to your WOT rpm area so you don't overload the motor.

Will running it below the recommended wot range overload the engine? According to Mercury, wot should be between 4400-4800.....I run it at 4-4200 max......

 

[Trash]

If you are thinking that the prop is slipping going down on pitch will make it slip more.

That's not true at all.

The key is the second part of your question relating to WOT recommended rpm etc.

To truly solve his dilemma we need more data through out the entire rpm band.

I recommend taking GPS speeds at 200 rpm increments from idle to WOT. THEN you can see what the prop is doing. Slip is not a constant and changes drastically through the rpm band. Slip at idle is approaching 50% in many cases and doesn't get less than that until around 1800-2200 rpm when a normal V hull begins to plane.

As stated earlier being a pontoon boat aggravates things as they don't quite plane the same, nor is the prop fed the same.

For this application I'd run the biggest diameter prop at a pitch that will allow max WOT rpm. I'd also look into a 4 blade prop.

 

[HavaToon]

Will running it below the recommended wot range overload the engine? According to Mercury, wot should be between 4400-4800.....I run it at 4-4200 max......

Yes, absolutely it can/will.

 

[HavaToon]

What prop are you currently running?

 

[outboardrick]

Will running it below the recommended wot range overload the engine? According to Mercury, wot should be between 4400-4800.....I run it at 4-4200 max......

When you say you're running 4-4200 max, does that mean WOT or that's just as fast as you push it? If you normally run at or close to WOT then try to get it into the recommended range. If you normally run at half throttle then it's not as big of a concern.

 

[Waffles]

What prop are you currently running?

Right now I'm running the black max 16" 14p (48-16438a45)

When you say you're running 4-4200 max, does that mean WOT or that's just as fast as you push it? If you normally run at or close to WOT then try to get it into the recommended range. If you normally run at half throttle then it's not as big of a concern.

Not true wot but as wot as I'm willing to push it. I've generally ran it at 4k thinking the harder I run it the worse it is for the motor but if it's the other way around, I'll start running it at it's true recommended wot range

 

[outboardrick]

Right now I'm running the black max 16" 14p (48-16438a45)

Not true wot but as wot as I'm willing to push it. I've generally ran it at 4k thinking the harder I run it the worse it is for the motor but if it's the other way around, I'll start running it at it's true recommended wot range

WOT rpm is really only used for getting the correct size prop. The reason I asked is that if your WOT rpm is in the recommended range then running 4-4200 is ok.....If that were true WOT rpm and that's where you run it then you need a smaller pitch prop. Pontoons that are relatively slow seem to be run at higher rpms most of the time. As has been mentioned in most of these replies, its usually trial and error. I had an old 24ft Party Barge with a 115 Johnson and it liked the smallest prop I could find, and it went faster with the smaller prop.

 

[HavaToon]

Right now I'm running the black max 16" 14p (48-16438a45)

Not true wot but as wot as I'm willing to push it. I've generally ran it at 4k thinking the harder I run it the worse it is for the motor but if it's the other way around, I'll start running it at it's true recommended wot range

Ok, based on this, you should be able to hit true WOT I'd stay with what you got or go with the enertia 14p if your looking for every last ounce of performance.

And you don't need to run true WOT, you can cruise at any rpm. It only matters when you run true WOT and the prop is to big not allowing you to reach the recommended RPM range.

 

[Waffles]

Ok, based on this, you should be able to hit true WOT I'd stay with what you got or go with the enertia 14p if your looking for every last ounce of performance.

And you don't need to run true WOT, you can cruise at any rpm. It only matters when you run true WOT and the prop is to big not allowing you to reach the recommended RPM range.

What am I looking at "performance" wise if I were to go with the enertia? Will I feel a noticeable difference with a smaller 15" prop with the same pitch or is more of a cosmetic factor since it's stainless.
I'll be out again in a couple of weeks to run it as it sits at the recommended wot range before making any decisions.

 

[HavaToon]

What am I looking at "performance" wise if I were to go with the enertia? Will I feel a noticeable difference with a smaller 15" prop with the same pitch or is more of a cosmetic factor since it's stainless.
I'll be out again in a couple of weeks to run it as it sits at the recommended wot range before making any decisions.

Because it's stainless vs aluminum there won't be the blade flex. I would guess that you would see small improvements through all rpm range maybe 1-2mph. But I think the biggest change you will notice is in cruise speed vs rpm and fuel economy. I would also think that if you currently experience any cavitation or blowout this will be greatly reduce possibly eliminated.

 

[Waffles]

Because it's stainless vs aluminum there won't be the blade flex. I would guess that you would see small improvements through all rpm range maybe 1-2mph. But I think the biggest change you will notice is in cruise speed vs rpm and fuel economy. I would also think that if you currently experience any cavitation or blowout this will be greatly reduce possibly eliminated.

Perfect. Thanks for your input 🍻

 

[Waffles]

Got this beaut in from brown santa today and wow....What a huge difference between the enertia and the elephant ears it has on right now. Itching to drive out this weekend and try it out 🤙

 

[HavaToon]

Got this beaut in from brown santa today and wow....What a huge difference between the enertia and the elephant ears it has on right now. Itching to drive out this weekend and try it out 🤙

View attachment 573806 View attachment 573807

Enjoy! I'm sure you'll be happy with the results. Let us know.

 

[mobldj]

let us know if you still get prop blowout

 

[HavaToon]

Well? How'd it run?

 

[Waffles]

Well? How'd it run?

Didnt get a chance to go out unfortunately. Got hit with a 102 fever that night that lasted till saturday night. Trying to go out this weekend.

 

[Waffles]

So here's my overall reaction with this prop....WOW.

I definitely noticed an improvement out of the hole and top end. Moving around the ramp and docks is also easier now. I'd have to give the old elephant ears some love for it to move whereas now the thrust/reaction is almost instant. This thing grips. Top end I ended up gaining an average 3.5mph which doesnt seem like a lot but it's a lot more than I was expecting. Only thing that somewhat concerned me is WOT. This prop seemed to have dropped it's true wot to around 4300 where the old prop I still had some left in the throttle to get the rpms up.

 

[Waffles]

Going up river full tank dual Bimini up

Vs down river with half a tank dual Bimini up.

 

[MSum661]

So here's my overall reaction with this prop....WOW.

I definitely noticed an improvement out of the hole and top end. Moving around the ramp and docks is also easier now. I'd have to give the old elephant ears some love for it to move whereas now the thrust/reaction is almost instant. This thing grips. Top end I ended up gaining an average 3.5mph which doesnt seem like a lot but it's a lot more than I was expecting. Only thing that somewhat concerned me is WOT. This prop seemed to have dropped it's true wot to around 4300 where the old prop I still had some left in the throttle to get the rpms up.

You just hit the point where your motor can't pull the new prop. Lol....you know what that means, mo $$$$.

 

[Waffles]

You just hit the point where your motor can't pull the new prop. Lol....you know what that means, mo $$$$.

I was afraid of this lol. Going down in pitch will increase my rpms right? What are my options? 15.6x13p? 16x11p?
Mind you this is what Mercury recommends

 

[Runs2rch]

How was the 3-3500k cruise speed where you probably spend most of the day.

 

[HavaToon]

Your motors rpm band is 4400-4800. I'd say stay with the 14P or drop to the 13P. I wouldn't go all the way down to the 11P as you will loose midrange and top end by a lot.

 

[Waffles]

How was the 3-3500k cruise speed where you probably spend most of the day.

Definitely not by choice lol. Didn't know why at the time but the faster I went the more water I would take in the bilge area. Didn't know what was causing this at the time so I had to cruise back down. Long story short. There are panels of aluminum between the center pod and the pontoons that "protect" the engine wiring and such. The rivets on the front end of the left panel ripped off( I'm assuming from the wash created by the center pod and toon and age) and with the pressure bent that sheet of aluminum straight down about a foot at a 90? angle creating a scoop for the water to get into the engine bay. Such a cluster lol