New member with a lengthy prop question

[StormH2Oguy]

I am definitely not new to boating but this is my first post here and I'm hoping that some of you technical guys can give me some advice. I have a 2007 Bentley 24' pontoon with a 2007 Mercury 115 HP 4-stroke. The engine runs great and has been serviced at regular intervals. The motor came with a 14x11 prop. For the last 2 years it has run great and I have not noticed any problems with it but mostly all we did was ride around the lake. This year we have started tubing with my 2 boys more and taking a few more people out with us. What I have been noticing is that in sharp turns and when going through rough water (like the wake from another big boat) the prop will occasionally loose it's bite in the water and the engine will rev up 600-800 RPMs, the boat will slow down quickly and I will have to back off the throttle and let it get it's bite again.

The engine currently runs at 5800 RPM at wide open throttle and that pushes me along at 24 MPH (GPS verified). The manual states that the WOT range for this engine is 5800-6400 RPM so I have room to move up in the RPM range some safely. Here is my question, I bought a spare prop from Turning Point propellers using their prop selector and it suggested a Hustler 14x13 for speed and a 14x11 for water sports usage so I bought the 14x13. I got a nick in one of the blades on the original Mercury prop a few weeks ago so I swapped it out for the new Turning Point prop. When I removed the original one I noticed then that it was stamped 14x11. I put the new 14x13 Hustler prop on and today when we went out the engine was revving at 6600 RPM and I still had about 1/4 throttle left but the boat was only going 18 MPH and felt very sluggish. I immediately pulled onto a sandy area and put the old prop back on and ran with it for the rest of the day and it did occasionally loose bite again but my RPMs were where they needed to be. I will be calling Turning Point next week to swap the Hustler prop out but what should I be running? If my original 14x11 prop is loosing bite and is at the low end of my WOT RPM range should I swap the Hustler 14x13 for a 14x11 or should I go down to a 14x9? What about extra cupping or a smaller diameter like a 13.5 or 13.75. Any suggestions before I throw more money at this. The prop is not slipping as I have checked the Flo-Torq II hub insert and it is perfectly fine. The motor also appears to be sitting just right in the water. Any advice would be appreciated.

StormH2Oguy

 

[steelespike]

Re: New member with a lengthy prop question

It has appeared on here that the Hustlers are very agressive but also un predictable sometimes to the point of suspected miss labeling. It appears to me the Hustler is just plain wrong for your application. When I saw it was a 13 I figured you would lose 300 to 400 rpm.
I believe Turning point makes a 4 blade prop but I don't know what to tell you about pitch at this point.A 4 blade prop will resist Ventilation(losing bite)should have better(lower) slip numbers.(pontoons do produce higher slip numbers).The 4 blade should also respond better at the dock.
Maybe Turning point can suggestr a pitch size.On a pontoon If there is a choice of diameters go with the larger. Typically when going from 3 blade to four they suggest a 1" reduction in pitch from the present prop.

 

[StormH2Oguy]

Re: New member with a lengthy prop question

Thanks steelespike. I am curious to see what Turning Point recommends after seeing how the 14x13 performed given that it was one that their Prop Wizard recommended. Does anyone else have any insight on good props for big pontoon boats?

 

[steelespike]

Re: New member with a lengthy prop question

The solas amita 4 blade has been very predictable on most applications
Perhaps someone has a particular prop or experience with a prop on their pontoon.

 

[luckynickles]

Re: New member with a lengthy prop question

i do know when pulling tubes or what ever skiers exc. you really need to put a power prop on as far as over winding when in a turn yu need to watch what you are doing you will spen a bearing on engine so be careful ask your dealer he'll be able tohelp and power prop means just what you hear power to take off and pull not speed you wont be going as fast but less torque on motor

 

[reddogg]

Re: New member with a lengthy prop question

You may also want to add a little cup to help it hold it's bite, esspically in turns.

Red