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Proper prop

Discussion in 'Members Zone: Props and Power' started by Totak, May 28, 2013.

  1. Totak

    Totak Member

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    Help Needed: Boat: 2013 22 SSX with sea legs, 115 Yamaha 4-stroke, and 25 inch toons

    Prop: Came with 13 pitch Yamaha aluminum. It was hitting the rev limiter and the GPS speed was 20mph

    Switched to a 15 pitch. Hit 5950 rpm at 22.5 mph

    Thinking of trying a 17 pitch. Any predictions or recommendations? My dealer says the 17 will slow it down. I was hoping to get 27-28 mph. I know the sea legs will slow it down. I just want maximum efficiency, etc.
     
  2. cwag911

    cwag911 Moderator

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    I think a 17p will be too much. Is the boat underskinned? You have the added weight of the Sea Legs also.
     
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  3. Totak

    Totak Member

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    No underskinning due to sea legs. Thanks for the feedback.
     
  4. Shawn

    Shawn Well-Known Member

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    I don't have much help to offer, however, I have a 24SLi with a 115hp and see typical GPS speed of around 27mph - getting 29 once with very clean logs. Your speed seems to be lower than what I would have expected. Others will have prop advice...
     
  5. keithkz

    keithkz Well-Known Member

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    The 17 will not 'slow it down.' What is your motor's max RPM? What is it's 'optimal'RPM range? What diameter prop are you using (14.5"etc)? The more pitch you can turn with the RPM's being near the max RPM range for the boat the faster your boat will go. That said I would bet the 15 pitch will be best for that motor. So perhaps a larger diameter than what you are using is what you should try.
     
  6. Totak

    Totak Member

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    Thanks Keith. The RPM max is 6000 with a range of 5000-6000. The prop is a 15x13.75.
     
  7. keithkz

    keithkz Well-Known Member

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    I would try going up in diameter first....say a 14.25 or 14.5, and keep the 15P. That will lower your RPM's a bit but of course you don't want to lower them too much or you will decrease your speed. I have a really hard time believing that motor will turn a 17P prop. But I would also ask the experts at propgods.
     
  8. Bigtop

    Bigtop Well-Known Member

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    Totak,

    Just FYI, your running a 13.75 pitch prop, not a 15. Which is unusual as i have never seen a stock prop with a pitch that is a partial number such as your 13.75. Usually they are 13, 14, or 15 and so on. The first number is your diameter and the second is the pitch. Be sure when comparing speeds with other boats that you are comparing apples to apples. Shawn posted above his speeds of 27 to 28, but it doesn't have his exact setup such as number of tubes and size. Go to the pinned post on here regarding members prop and speed to a more true comparison. Changing the pitch or diameter will change your performance. A good general rule of thumb is to have your boat peak out on RPM's with your typical load. Looks like your real close with the prop you have. Just my two cents.
     
  9. Ben & Suzy

    Ben & Suzy Well-Known Member

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    A larger diameter prop is typically a good suggestion, but in this case, 14.25-14.5" is wrong. The Yamaha F115 has the smaller gearcase which will accept a maximum diameter of 14".

    The boat should easily run into the upper 20's mph range with a 15p. IMO, you have other issues and the prop isn't the culprit. The first thing I notice when looking at those RPM / Speed numbers is that you have a HUGE slip percentage of over 40%. You need to look elsewhere for the problem. Is the engine mounted too high? Are you over-trimming the boat? I have no experience with boats using Sea legs, but I think that's the next place I would look. Could the Sea legs be causing a disturbance in water flow to the prop? Something is causing the prop to slip.
     
    Last edited by a moderator: May 29, 2013
  10. keithkz

    keithkz Well-Known Member

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    Wow 40% slip? And I thought mine was bad at 24%. Cannot wait for my new prop to arrive this week from propgods.
     
  11. Ben & Suzy

    Ben & Suzy Well-Known Member

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    That new Enertia should be a nice improvement for you. If it isn't exactly what your boat needs, Ken @ Propgods will be more than helpful in getting you the right prop. If you need any custom work done to get it right, he uses one of my favorite prop guys, Rich Junker @ Leading Edge Propellers. Rich has cut a few drag props for me. My best all around performing 16" diameter prop for our tritoon was cut by Rich. It is the smoothest running 3 blade I've ran to date. I guess that's why I like it soooo much. It may not be my fastest prop, but the overall performance is well worth the trade-off for a few mph on top IMO.
     
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  12. keithkz

    keithkz Well-Known Member

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    Yeah Ken has been great and he told me the same thing....that if this Enertia isn't the perfect setup to send it back and he will send a different one. I feel like a kid waiting for Christmas to come waiting for this prop to arrive.
     
  13. Totak

    Totak Member

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    My mistake. It's a 13.75 x 15 pitch. I had the numbers turned around. Thanks for all the ideas. I've got some experimenting to do.
     
  14. keithkz

    keithkz Well-Known Member

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    Yeah I figured that's what you meant the first time you posted that actually.

    I really think you're right there...like I said, you want to be near the max RPM with the largest pitch that motor will turn and you appear to be there. No way should you be able to turn a 17P with that 115HP motor. If you still think you need to come down a little on the RPM's then go to a slightly larger diameter....say a 14 or 14.25. 15P is the pitch you should be using though.
     
  15. v1rot8

    v1rot8 Member

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    I think I have some information that may help you with your search for the proper prop. My boat is nearly identical to yours. I have a 22 SLMX with a Yamaha F115 four stroke. The pontoons are 25" diameter with no lifting strakes. I drove myself crazy about 2 months ago dealing with the same issues you are having with your propeller. My dealer set my boat up with the 13pitch Yamaha propeller when I picked it up also. In fact, Bennington provides the dealers with a chart that gives propeller recomendations based on motor and pontoon. For a 22' pontoon with the F115 engine they recommend two different propellers. The first being the aluminum 13 pitch you started with and the second being a Yamaha Stainless Steel 14" x 13 pitch (MAR-PNTN3-V4-13).

    My boat also hit the rev limiter (6250 RPM) and was ventilating when I first ran the boat. My top speed on the GPS was 27MPH with this prop. When I brought the boat back to the dealer and discussed the issue with him he installed the 14" x 13 Yamaha prop mentioned above and told me to try it. I have had lots of issues with my dealer and feel that he is always trying to make a quick dollar rather than having my best interest in mind. Needless to say when he put the stainless prop on I thought it was just a way to get another $400 out of me. Reluctantly I dicided to give it a try. If you read this forum and many others the value of a Stainless Steel propeller is ofen debated especially on a 115hp engine. I will leave you to read about the pros and cons of stainless but the performance spoke for itself. With the 14" x 13p stainless the boat ran at 6000 RPMs and on the GPS the top speed was between 31 and 32 MPH. I was pleased with the holeshot and the top end speed.

    *****By the way the boat was loaded with a full tank of gas and my son and myself with a collective weight of 300 pounds. Weather conditions were roughly 60-70 degrees for all of the props. and winds pretty much calm. *****

    Not beleving that I needed a stainless prop on a pontoon I set out to find an aluminum propeller that would perform as well.....I went to a local prop shop and he was nice enough to fill the back of my truck with a bunch of new props. He let me try them and bring back the ones that I did not want. I tried several brands and sizes.

    Here are my test results:

    1) Yamaha 13 pitch 6250rpm on rev limiter 25-26MPH (aluminum)

    2) Yamaha 13.5 x 15 pitch (6E5-45947-00-00) 5400 rpm 26-27 MPH (aluminum)

    3) Mercury Black Diamond (QA2034x) 13.75" x 15 5200 RPM 26-27MPH (aluminum)

    4) Mercury Black Diamond (QA2032X) 14" x 13p 5900RPM 28-29MPH (aluminum) ***** BEST PERFORMING ALUMINUM PROP I FOUND AND IS NOW MY SPARE****

    5) Mercury Black Diamond (QA2832X) 14" x 13p "Pontoon Extra Cup" 5100 - 5200RPM 25-26MPH (aluminum)

    6) Yamaha Stainless Steel (MAR-PNTN3-V4-13) 14" x 13p Pontoon 6000RPM 31-32MPH *****BEST OVERALL PERFORMANCE****

    ****By the way the Mercury Props require you to buy a Flo-Torque hub kit (835271Q2) it cost me about $50****

    In the end I decided to keep the Yamaha Stainless Steel 14" x 13 pitch (MAR-PNTN3-V4-13) on the boat a my main prop. If you search for the Yamaha Performance Bulletin PB-BNT-24SLi-F115TLR-2010-10-13-PNT you will find this propeller is tested on a 24' Bennington SLi. Given the fact that my top speed and RPM data is nearly identical and it is one of the two props Bennington recommends for our combination of boat and motor I think it would be worth giving a try. I agree with the others that a 17 pitch sounds way too high for your boat. I hope that you find this information helpful....Before buying my boat I thought that the dealer would just set the boat up with the proper combination and I would be all set....What I found was that it takes a whole lot of trial and error to find the right combination. As you can tell by the responses on this forum everyone has different combinations that work well for them.
     
    Last edited by a moderator: May 31, 2013
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  16. kaydano

    kaydano Well-Known Member

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    5 MPH improvement from aluminum to stainless steel on a 115 HP motor is a huge delta. So much so, that I wonder if there are other design differences (such as cup, for example) that are coming into play here.

    Top speed is one measure. Acceleration and torque is another. Usually one improves at the expense of the other. So, it would be nice to know the acceleration numbers for those props too (such as the 0-20 mph time, for example). I've posted before that I wish there was an app for this (enter the speed, such as 20 mph, and then the app starts the clock as soon as you start accelerating and it stops the timer at 20 mph). You might find the aluminum was quicker out of the hole, and might have better holding power for a heavy boat and tubing, while the stainless has better top end. Do you know for sure these are identical props in all respects except for the metal?

    Your information is very valuable, as I've been trying to piece together the prop puzzle myself for some time. Thanks for posting this.
     
    Last edited by a moderator: May 30, 2013
  17. cwag911

    cwag911 Moderator

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    Excellent write up.
     
    Last edited by a moderator: May 30, 2013
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  18. v1rot8

    v1rot8 Member

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    1) The Yamaha props were the same except for the change in pitch.

    2) The Mercury props were all the same except the change in pitch with the exception of the "pontoon extra cup" prop I tried.

    3) The 14 x 13p regular is the same as the 14 x 13p "pontoon extra cup" with the exception being one was cupped more that the other.

    4) Their was a difference in the overall geometry between the Mercury and Yamaha props that was clearly visible.

    More importantly a shiny polished stainless prop looks nicer than the ugly white aluminum Yamaha :eek: )
     
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  19. kaydano

    kaydano Well-Known Member

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    Well then, 5 MPH for $400 is more bang for the buck than you can get from tubes, strakes or HP! Shows the importance of getting dialed in on the right prop...

    Agree with Carl, excellent write-up.

    Any chance you might feel like going out and testing a Spit Fire???
     
    Last edited by a moderator: May 30, 2013
  20. Link

    Link Moderator

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    Thanks Bowen, great info for the rest of us. Maybe this should be copied and pinned into Eric's Power & Props section. Speaking of Eric, where has the sage been recently? Miss his wisdom but probably busy with the zombie apocalypse
     

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