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Thread: 53MY Repower

  1. #11

    Re: 53MY Repower

    The 7.1 cat is too small. Not enough mass to get a good life out of them.

    Keep in mind the old engine was over 9 liters and heavy duty. That's why they lasted.

    QSM 11 would be far better. Or talk to Sky Cheney. He's doing it right now with cats. He's putting in 8.7 liter engines.
    Scott
    41C117 "Hattatude"
    Port Canaveral Florida.


    Marine Electronics and Electrical Products Distributor.

  2. #12

    Re: 53MY Repower

    when my boat was repowered the PO left the 32 volt stuff in place and put an 8d in each engine room, 1 for each engine. they also had a 12v battery to run 2 heads and a 12v battery for the generator. i have since swapped everything over to 12 volt
    Mis b' havin
    1972 58 yachtfish
    58yf352
    pass christian, ms.

  3. #13

    Re: 53MY Repower

    Attachment 54383
    Attached Images
    Last edited by SKYCHENEY; 11-10-2021 at 10:27 PM.
    Sky Cheney
    1985 53EDMY, Hull #CN759, "Rebecca"
    ELYC on White Lake--Montague, MI

  4. #14

    Re: 53MY Repower

    Quote Originally Posted by SereneWarrior View Post
    Pascal, the Cat C7.1s are rated at 450hp and get good reviews re reliability. Local marine engineer thinks the project will take “a couple of months”, but my experience is that any time estimate for boat projects should be at least doubled. What was your experience? How long did your repower take? This is a relatively small firm with only 5-6 folks. They’ve done great work for me in the past, but tend to be overtasked.
    Just for grins I ran the re-power duration numbers through the old project management estimator, "PERT". Its old but works, plus has statistical analysis capabilities. I will skip all the wild PM PERT stuff, which requires full coursework.

    What I used, in months, per the conversations here:
    Optimistic 2 Mos
    Likely 9 mos
    Pessimistic 24 mos

    PERT tool sez [ Optimistic + (4 x Likely) + Pessimistic ]/6 = [ 2 + (4 x 9) + 24 ]/6 = 62/6= 10.3 mos Probably duration.

    It would be fun to know how close the tool is to actual experience.

    Long time PM guy... Note: Per the remarks as well, you need one or more "stars" on your projects, i.e. people who really know their stuff!
    50 Years on the Great Lakes...

  5. #15

    Re: 53MY Repower

    There is a 53' my in our cruising club which was repowered w C series Cummins. Performance numbers about like Pascal's and has run nicely for years. I'd look at those. I don't know which Cats are the 7.1s, but if they are related to 3126s I'd avoid them/

  6. #16

    Re: 53MY Repower

    My friday "Dream proyect" is to repower my 58 YF . I am considering the Scania 6 cil 500 hp engines. My plan is to leave all the 32 V systems intact and add a 12v system for the engines only. The problem with a proyect of this size is the "Since" word. That is what takes the cost trough the roof.

  7. #17

    Re: 53MY Repower

    Sky, I must have missed something, this is the first I have heard about your repower could you start a thread and keep us posted as to your progress, I think most of us would be interested. John
    Mahalo V
    1974 53 Motoryacht
    Hull Number 406
    San Diego, Ca. Ready 32 Nordic Tug, Brunswick Ga.

  8. #18

    Re: 53MY Repower

    Agreed. Sky that looks like it’s going to be awesome. All I’m thinking is that’s 200 more horsepower than I have now and how great the boat would perform with the extra ponies. New engine beds I’m sure but what about shafts? You had the 6-92’s before right? What were those, 500 up?
    John
    1981 58 Yachtfish Hull 477
    Wickford RI

  9. #19

    Re: 53MY Repower

    Thanks, everybody! Some great inputs here and lots to think about. Keep it coming as you think of any other considerations. As always, this forum rocks!

  10. #20

    Re: 53MY Repower

    Quote Originally Posted by johnjen50 View Post
    Agreed. Sky that looks like it’s going to be awesome. All I’m thinking is that’s 200 more horsepower than I have now and how great the boat would perform with the extra ponies. New engine beds I’m sure but what about shafts? You had the 6-92’s before right? What were those, 500 up?
    The 692's were 465, the Cat 8.7's are 650. New engine beds, new struts, new shafts. Its a big project. I was waiting to post until I finished and had some performance numbers, but I might start a thread since the CAT is out of the bag, so to speak.
    Sky Cheney
    1985 53EDMY, Hull #CN759, "Rebecca"
    ELYC on White Lake--Montague, MI

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