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45 Express Repower

Discussion in 'Cabo Yacht' started by MC02020, Oct 16, 2026.

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  1. MC02020, Oct 16, 2026
    #1
    MC02020

    MC02020 New Member

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    Sep 11, 2019
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    Brant Rock & Falmouth, MA
    I am getting close to pulling the trigger on a repower on our 2000.

    We have 800 MAN mechanicals with 4800 hours and then are just getting to expensive to keep putting money into to keep them running and reliable.

    We have had the boat for the last 7 years and plan to keep at least another 5. I have already updated all of the other boat systems, Generator, ACs, water maker, electronics, etc so have too much invested.

    I am planning on MAN i6-850 as they appear to be one of the only options that really fit int he boat without too much difficulty and can retain running gear.

    Does anyone know of a 45 that has undergone a repower? While I think we have all of the challenges accounted for, would be great to connect with someone that has already gone through it and lessons learned.

    Thanks in advance!
  2. Capt Ralph, Oct 16, 2026
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    I always admired the power if the MAN R6, 800 HP.
    Sweet engines.
    Look forward to your feedback on the newer 850HP models.

    Are you having problems finding parts or their just expensive?

    I am assuming you have the V8-800s.
    Does your existing clutch already have a down angle propeller shaft out flange?
    I fear you will need it going to this tall in-line 6.
  3. ranger58sb, Oct 17, 2026
    #3
    ranger58sb

    ranger58sb Senior member

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    Our MAN guy told me the I6s are significantly lighter than our V8-900s (same block as your V8-800s, if that's what your originals are). So you could probably go with the lower 750 or 800 ratings if you wanted to...

    But at the replacement costs he suggested -- ~$85K each including gears (plus labor), this during a theoretical "what if" discussion, nothing more -- I'd guess the V8-800s would run forever at maybe a tenth of that $$$ or less.

    The inline 6s would likely improve the centerline of your engine room.

    But maybe you just need a better MAN guy?

    -Chris
    Capt Ralph likes this.
  4. Capt J, Oct 17, 2026
    #4
    Capt J

    Capt J Senior Member

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    I would think the Man V8 1200HP would fit and the boat would scream. I ran a bunch of those boats. C18's at 1000 hp cruised at 30.5 knots with tower and fit as a straight 6, The v10- 1100HP Man's also fit and were the best in that boat IMO 33 knot cruise and quiter. I6's run well and would do well also and at 850hp and the lighter weight your 28 knot cruise should pick up 1-2 knots, if you need to reprop, Veems were the best on those boats. I don't recall the c18's having a down angle propeller shaft output flange.
  5. CaboFly, Oct 18, 2026
    #5
    CaboFly

    CaboFly Active Member

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    The MAN V8 1000hp would pair well with that hull I would imagine.
  6. Capt J, Oct 18, 2026
    #6
    Capt J

    Capt J Senior Member

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    Same motor as the 1200 hp, just different ECM, Might as well go with the 1200 hp......unless you could re-use the 800hp shafts/struts/etc. by sticking with 1000hp.......
  7. Capt J, Oct 18, 2026
    #7
    Capt J

    Capt J Senior Member

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    C18 CAT will also fit right into that boat as well and Cabo built many of them with C18's (they're a straight 6), however noticeably noisier than the MANs. I think the I6's will be a good choice.
  8. CaboFly, Oct 18, 2026
    #8
    CaboFly

    CaboFly Active Member

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    I looked at some pics of 45’s with C18’s and forward of the engines looked really tight to me. If you do much of your own maintenance I would put a premium on ability to get to things vs purely performance.
    Capt Ralph and chesapeake46 like this.
  9. boatpoor, Oct 20, 2026 at 7:58 PM
    #9
    boatpoor

    boatpoor Senior Member

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    I've never owned, operated or maintained a Man engine but based on what I've read and heard I'm surprised to hear someone planning on replacing a pair at less than 5000 hours. And I'm wondering how much more dependable a computer controlled engine will be than a mechanical one? However, if you're just looking for more speed you're probably headed in the right direction.
  10. ranger58sb, Oct 21, 2026 at 8:01 AM
    #10
    ranger58sb

    ranger58sb Senior member

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    Back to OP -- you still there?

    Are existing engines inline R6-800s? Or V8 2848LE401s or 403s or whatever?

    What is it about them that's causing you heartburn? Difficult to imagine it being cost-effective to spend a bazillion dollars on full replacement unless the originals have had something catastrophic happen to them...

    -Chris