WOT RPM New vs 10 yrs later

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by DieselDogg, Mar 16, 2019.

  1. DieselDogg

    DieselDogg Member

    Dec 18, 2013
    Hopefully you guys don't beat me up too much for asking a question on a non - Sea Ray boat, but I just can't think of a place that has more knowledgeable folks than CSR. Didn't think we would find ourselves in a situation where we are buying something other than Sundancer, but we came a cross a trawler at a boat show that we absolutely fell in love with.

    We had the mechanical inspection yesterday. The boat has a single John Deere 12.5L diesel model 6125SFM75M4. This is a commercial duty motor with 610 hp rating. The boat is a 2008 45 ft semi-displacement hull. It's a one owner boat that spent the last 10 yrs in a boat house and clearly has been loved and cared for. She has about 1250 hours on the clock.

    When she was built originally, the owner had John Deere do all sorts of tests as part of commissioning. I was able to get my hands on those test results and compare them against the results from yesterday.

    Per John Deere specs, the max RPM is 2100. When new, JD did 5 test runs and achieved an average of 2118 RPM (the range was 2125-2114).

    Yesterday, at WOT, we were able to get to 2060. We had very calm water yesterday, so that was pretty nice. We also had similar load. I do not know about the condition of the bottom paint and props. We'll find out on Mon when we have the survey.

    I know that the boat was well maintained, but the owner passed away about 3 years ago and the boat has not seen a whole lot of use. If I had to guess it was started a few times, but wasn't ran consistently most likely.

    My question is, should I worry that we were shy 60 RPM from when the boat was new and is the fact that it sat around for at least 2 years something I should be concerned about?
  2. ENstig8or

    ENstig8or Member GOLD Sponsor

    Jun 4, 2013
    New Jersey
    2003 Sea Ray 450 Express Bridge.....

    2016 Sea Ray 21 SPX BR
    Cummins 480CE (450)
    Mercruiser 4.3L (21 SPX)
    Fresh bottom paint can easily make up that difference assuming there are no other issues.
  3. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    Subtle prop changes, bottom paint, water conditions, weather all effect how a motor pushes you through the water. Not to worry in my view. Our boat is 15 years old and shows a little variation each year. Last year it turned about 75-100 rpms faster than when it was brand new. newsbw14.JPG
  4. DieselDogg

    DieselDogg Member

    Dec 18, 2013
    Thanks guys. Makes me feel better about the numbers.
  5. mnm99

    mnm99 Well-Known Member

    Oct 2, 2015
    Long Island
    2004 340 SeaRay Sundancer
    Twin 8.1 Merc
    100 rpm..LOL that could be wind, current, prop adjustment, weight ect...If you were saying 400-500 then I would worry.

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