New EFI and New Motor Height = New Prop Needed

Discussion in 'Prop Shop' started by rkmurphy, Nov 1, 2009.

  1. rkmurphy

    rkmurphy Well-Known Member

    I'm currently running an 11 pitch prop on my new 2007 Mercury 25 EFI. The motor is set back ~4.75" and the cavitation plate is about 2.5-3" above the bottom of the boat. Currently, I'm getting around 28 mph with 2 people, fully loaded, in a light chop. The speed seems fine but I feel as if I'm hitting the rev limiter. I was watching the GPS and it would hit 28+ mph and then drop to 25-26 and climb back up. The wind was going pretty good so it was hard to hear a change in RPM (plus the EFI is so damn quiet! :) ).

    No tach yet...I know that complicates things...one's coming in the relatively near future.

    Any EXPERT advice? I'm still awaiting an email reply from Capt. Ron but was wanting input from others as well.

    I'm wanting this thing to be able to blast out of the hole, hold water, and get some good mid-range and top-end speeds. I'd be willing to sacrifice a little top end for some hole shot. Would still like to be pushing 30+ mph WOT, though.

    Looking forward to some good responses!!! ;D
     
  2. mark_gardner

    mark_gardner I Love microskiff.com!

    sounds like your doing pretty good actually, the best i ever got out of my 4 stroke on the minnow was 27 mph with only me and a few rods and that was with a 12 pitch prop, always wanted to get a smaller one but never did, you could go with a 9 and that would probably jump you out of the hole nicely but dont think your gonna see higher speeds than what your seeing, your speed will change a few mph's depending on shifts in the wind, current etc...
     

  3. iMacattack

    iMacattack busy, too busy

    4,674
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    http://www.microskiff.com/reviews/products/Four-Stroke-Shootout/Mercury-25-hp-fourstroke.html

    2009 Mercury 25HP 4 Stroke
    Weight 184 lbs
    Gear Ratio 1.92:1
    Material Aluminum
    Prop Size 9.5 X 11
    Time to Plan 6.86 sec's
    Top Speed 26.6 MPH
    RPM MPH
    1,000 2.8
    1,500 3.9
    2,000 5.0
    2,500 5.8
    3,000 6.9
    3,500 8.5
    4,000 14.6
    4,500 18.2
    5,000 21.7
    5,500 24.8
    5,650 26.6
     
  4. rkmurphy

    rkmurphy Well-Known Member

    Hmmmm....

    Yeah I was satisfied with the speed but why do I feel like I'm hitting the rev limiter?
     
  5. TomFL

    TomFL Well-Known Member

    RK, I doubt you're hitting the rev limiter, but it's always a possibility given slip and the JP/setback. I'm no expert there.

    See my comments under your update thread about what I found that motor likes for propping.

    -T