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Prop/Motor Height Help

Discussion in 'Members Zone: Props and Power' started by DaveyJ, Jul 26, 2016.

  1. DaveyJ

    DaveyJ Well-Known Member

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    New to Bennington & Pontoons in general - Just before the 4th, we purchased a 2013 2375GCW with ESP, Yamaha F150, and Sea Legs.  Had 78 hours on it and was running a Yamaha 15 1/4 x 15 aluminum prop the day I took delivery and, with just me & 1/4 tank of gas, I was able to do 33.1MPH at WOT 5600RPM at 3/4 up on the trim gauge.  I was relatively happy with this since the Sea Legs add 570lbs and some drag.  I typically have had 6 - 10 people on board and have pulled a tube quite a bit and would max out at 23MPH loaded up at WOT 4800 to 5000RPM.  I decided I would try a 13 pitch prop to pick up mid-range loaded capability and hopefully bring the light load RPM's up closer to the 6000RPM mark with the loaded RPM's more into the WOT range of 5-6000RPM.  I switched over to a Solas Amita 3 16x13 aluminum prop a week ago and had some confusing results.  WOT with just me & a buddy on board and 1/4 tank of gas was 29MPH at 5400 RPM.  Trim seemed to make no difference in speed or RPM's I fully expected the RPM's to increase, not decrease.  The mid-range holding power seemed better but still would not exceed 5000RPM.  I am wondering if the drag of the Sea Legs is playing into the results.  The boat's normal attitude when sitting in the water is very "ass heavy" and I am wondering about trying to get some stern lift to allow better water flow between the toons.  Can raising the motor help to achieve this?  It's currently in hole #1 (lowest setting).  Also wondering about people's experiences with 4 blade props.  I know I eventually want a SS prop but am experimenting some prior to taking that plunge.  Thoughts?  Thanks!
     
  2. goldnrod24

    goldnrod24 Moderator

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    " I am wondering if the drag of the Sea Legs is playing into the results."


    This.


    The weight alone is equal to 3-4 passengers.
     
  3. DaveyJ

    DaveyJ Well-Known Member

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    I understand the weight is definitely an issue which is why I went to the 13 pitch prop in an attempt to compensate, at least partially, for it.  The RPM's going down is what confuses me relative to a 15 pitch prop.  I was wondering if, perhaps, the 13 pitch prop had more bow lift resulting in the stern being lower and the sea legs creating additional drag.  They are 8" wide and stick down roughly 7" from the frame so they definitely catch water.  If I was able to lift the stern, it would allow greater water flow between the toons, and, theoretically, create less drag.
     
  4. cwag911

    cwag911 Moderator

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    If you're playing with aluminum props, you won't get an idea of what a stainless prop will do. The first thing I got rid of on our boat was the solas aluminum prop.
     
  5. tcpip95

    tcpip95 Well-Known Member

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    The fact that you've got the Sea Legs installed will dictate that speed is not going to be a primary concern.  Sea Legs are DEFINITELY causing drag.  The risk you are running is that the low RPM at WOT is causing "lugging" of the motor; you're making the motor work too hard.  I would suggest two things:

    1. Raise the motor (by lowering at least 1 hole).  This should increase your RPM  by a few hundred RPMs.
    2. Get the Reliance 14.25 x 15P SS prop.
     
    Last edited by a moderator: Jul 26, 2016
  6. 1Blderbob

    1Blderbob Well-Known Member

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    You said the boat had sea legs when you bought it. Why anyone would spend alot of money for an option like ESP, just to hang an anchor that drags against the water. I'd get rid of the Sea Legs and sell them on Craig's List.And then put a stainless prop on the motor. Just my 2 cents.
     
  7. azray007

    azray007 Well-Known Member

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    I agree.  I would have the sea legs removed and add a stainless prop on that nice Yamaha 150.   :)
     
    Spoiledrotten likes this.
  8. goldnrod24

    goldnrod24 Moderator

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    Sea Legs on a tri-toon is a recipe for disaster. Very poorly engineered and not worth the risk, IMHO.
     
  9. DaveyJ

    DaveyJ Well-Known Member

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    Guys, I fully understand that the Sea Legs are a major hit to the performance of the boat (and damn near sacreligious on an ESP) but everything about this boat has been a compromise.  


    A little back story - until about 1.5 months ago, we had a 2005 Four Winns Horizon 180LE 4.3L 190hp which we had since new.  Came with a 14x23 aluminum prop which I eventually replaced with a 14 1/4x19 SS prop. GREAT boat and the SS prop performance was excellent.  Several months ago, my wife expressed a desire for a party barge.  She would have been good with a 60hp cruiser but I held fast that I wanted performance as well so we started looking at tritoons. Looked at several dealers and craigslist over the course of a month and eventually found this boat.  The doctor who ordered it new traded it in on a Q ESP with a 300hp (and Sea Legs).  


    It's a beautiful boat and, besides the performance concerns I have, does what we need.  We rent cabins with another couple (they have a 20' jet boat) every year, never the same one twice up to this point.  The Sea Legs allowed us to get on the water immediately and also not have to buy/store a lift.  We had a cheap 3k lift for our old boat but would need a substantially larger more expensive lift for the current boat.  Pulling lifts and hauling/storing them every year is a pain with the lighter lifts, much less a 5k+ lift. Basically, until we buy a lake cabin (at least 5 years out), the Sea Legs are here to stay.  We got the nicest boat we could for the budget we had and still have to buy a trailer so I don't have a lot of cash for modifications at this time.


    Sorry for being so long winded but wanted everyone to understand where I'm at.  The Sea Legs are staying so I'm trying to come up with ways I can minimize the performance hit and, in the process, get the motor into the WOT range it should be.  I'm not overly concerned about top speed, more midrange, loaded performance.  I think part of the key is to get the stern higher to minimize the drag.  


    SS prop is definitely the plan for next summer, most likely the Reliance prop in the performance bulletins or a Mercury Enertia prop which I've also read great things about.  Does anyone know if either prop design promotes stern vs bow lift? Thanks again for the input!
     
    tcpip95 likes this.
  10. tcpip95

    tcpip95 Well-Known Member

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    Davey, sounds like you've thought it all out.  Enjoy the boat!  That's the most important thing.
     
  11. DaveyJ

    DaveyJ Well-Known Member

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    I've got lots of theories but they don't always work out like going to a 13 pitch prop which is why I'm here.  Thanks for the motor height and SS prop advice!  Definitely enjoying the boat!
     
  12. azray007

    azray007 Well-Known Member

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    If removing the Sea Legs are a no-go for now, I would really try to make the swap to a stainless prop asap.  I'm guessing you would see an immediate gain in overall performance,   Good luck!!! 
     
  13. Michiman

    Michiman Well-Known Member

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    Just came across your post. Unless I'm missing something, I think the natural attitude of an ESP is "ass heavy" as you state above. I don't think you'll be very successful trying to change that condition so I'd try to focus on getting the correct SS prop. Good luck and enjoy that Benny. BTW, we came from a 2006 Four Winns which we purchased new and sold last spring to join  the pontoon crowd for precisely the same reason. My wife was definitely the driving force...
     
    DaveyJ likes this.
  14. DaveyJ

    DaveyJ Well-Known Member

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    Well, I got a chance to demo an Enertia 15.25 x 14 last weekend and was, unfortunately, underwhelmed.  The Enertia gave me 2 MPH on the top end but caused noise/vibration up to about 1,000 RPM which is a deal killer.  It also didn't hold speed in the corners quite as well as the current aluminum prop.  Load was 3 people (roughly 450lbs) and about 200lbs of gear. The current prop grips very well with a load (was able to tow a 4 person tube with 4 kids on it with mix of 11 adults/teenagers in the boat last time in the water last year) but I would feel better with higher RPM's as I don't want to lug the motor.  Gonna try moving the motor up 1 hole and go from there.


    16x13 Solas Amita 3 E-Plus


    1000 - 3.6


    2000 - 7.4


    3000 - 12.5


    4000 - 20.0


    5000 - 27.1


    Wot - 5400 - 29.2


    15.25x14 Enertia


    1000 - 3.6


    2000 - 7.2


    3000 - 13.5


    4000 - 21.2


    5000 - 28.7


    Wot - 5400 -31.2
     
  15. cwag911

    cwag911 Moderator

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    The 16 x 13 prop has too much diameter. The Enertia has too much pitch for the load you want to carry, including the legs.
     
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  16. DaveyJ

    DaveyJ Well-Known Member

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    I thought about demoing the 13 pitch Enertia but the way the 14 pitch caused noise and vibration at low RPM makes me apprehensive about it.  Is this typical with stainless props due to the higher rotating weight?  Is it possible the prop was out of balance? My only boat prior to this was an I/O so I don't know how outboards act.  The Yamaha 150 is dead quiet with the aluminum props I've had on it.
     
  17. cwag911

    cwag911 Moderator

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    You need the Flo-Torq III or IV hub (I don't remember which I have) and it gets rid of the rattle. It suppresses the oscillations of the 4cyl motor.
     
    Last edited by a moderator: Jun 13, 2017
  18. DaveyJ

    DaveyJ Well-Known Member

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    Could be either based on some of the threads I just read.  I bought the II to demo the prop. I'll talk to the guy I demoed the prop from and see if he has any insights.  Thanks for the info!
     
  19. lakeliving

    lakeliving Well-Known Member

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    You should be able to get the SDS hub/prop for that 150 and not have any chatter.
     
  20. Michiman

    Michiman Well-Known Member

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    I have a GCW 2574 and between the boat and engine, I'm about 4000 pounds plus fuel, water, gear and passengers. Currently running an Enertia 15.6 X 13 and can hit a top speed of 40 MPH (one person, 3/4 tank, 12 gallons water) @ 6400 rpm. Under normal operating conditions (more passengers, gear, etc.) I'm still in the high 30's. No low rpm vibration. Not sure if any of this helps...
     

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