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Max RPM's duration at Sea Trial

Discussion in 'Technical Discussion' started by BoulderGT3, Aug 13, 2017.

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  1. PSW

    PSW Member

    Joined:
    Feb 13, 2010
    Messages:
    103
    Location:
    Bellevue, WA
    With 1600hp pushing 35k to 38k pounds the engines are not working very hard and I have not yet seen a WOT test that didn't have both motors exceed 2350. With that said I have only owned the boat 1 yr. I only post in an effort to learn as much as I can from you guys and am not trying to prove anything. As Pac Blue eluded to as well the PNW has very little growth in our cool waters and on top of that I keep the boat in an enclosed building so the only fuzz I have to knock off is the transom every month or so with a brush. The underwater metals have propspeed or some other similar coating that is also working as desired. Here is a pic from a fishing trip prior to haul out. I don't have any other photographed results but I do have seatrial from when I bought the boat and when it was commissioned new by MAN. I have compared the computer data from both commissioning reports and they are nearly identical to today across the board.

    Old bottom paint August 2017 2352/2372
    Sea Trial Florida Oct 2016 2350/2365
    Original Commissioning Data - New Boat 2357/2377
  2. PSW

    PSW Member

    Joined:
    Feb 13, 2010
    Messages:
    103
    Location:
    Bellevue, WA
    I agree completely. 37 knots is with neutral conditions. Attached is a pic from previous trip that had a nice current going with us. 20170806_160701 (Small).jpg
  3. olderboater

    olderboater Senior Member

    Joined:
    Sep 2, 2013
    Messages:
    7,132
    Location:
    Fort Lauderdale
    We have the same engines in the Rivarama and have always run slightly above the 2300 just as those here are posting, when testing it. Very similar except for speed. Also, like PSW in two years, we've seen very little change in five years.
  4. PacBlue

    PacBlue Senior Member

    Joined:
    Jan 9, 2009
    Messages:
    1,988
    Location:
    Dana Point, Ca
    Oh boy, 39 knots (with a little push), that is really honking for a 40 Cabo Fly!
  5. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    Because the engines are rated at 2300 rpms/100% throttle/ 100% load. So the boat is under propped a little and underloaded. Which is what MAN and everyone would like to see. If the engines only turned 2270 RPMs at 100% load/ 100% throttle, than they would be considered overloaded.

    I've run a 2007 62' predator with 1100hp common rail MAN's it has always turned 2360-2370 rpms 100% throttle 100% load, fully loaded with fuel, water, and owners gear. The top RPM's don't seem to change with more or less weight (1/2 fuel), but the 80% load RPM's change a lot with a few thousand pounds. But it too has always stayed the same.....
  6. Fiammetta42

    Fiammetta42 Member

    Joined:
    Sep 28, 2017
    Messages:
    130
    Location:
    Liguria Italy ( boat )
    Yes I see ,I have MAN,s too the 2876 -- 700 Hp ,they have a slightly longer stroke 12.8 L so they are rated a bit lower @ 2200 rpm .
    Pistons have a few extra mm to travel ,compared to the R 6 800 Hp variant .

    I can WOT over say 2275 - which gives head room for seasonal growth .
    Water is warm in the Med so we can easily snorkel or dive clean the stern gear. Keeping it reasonably clean .
    Normal cruise is 1780 rpm which = 27 knots @ 80 % load or there abouts .
    On this side of the pond we are low hr s compared to you guys
    I,am on 810 - boats 2003 .