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1981 Carver 33' Mariner Cruising RPM's???

Discussion in 'Carver Yacht' started by BaySailorBill, Jul 9, 2010.

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  1. BaySailorBill, Jul 9, 2010
    #1
    BaySailorBill

    BaySailorBill New Member

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    Narragansett Bay, RI
    Hi,

    I just finished a refit on a 1981 33 foot Mariner. She has twin 5.7L Mercruisers with Borge 1.1 V-drives.

    At what RPMs is a good cruising rainge for this boat?

    I have been running her at 2200 RPMs, but she doesn't seem to be getting out of her own way. The engines are brand new rebuilts and I'm reluctent to push them too hard. I know that she is designed more for comfort then for speed, but she should have a good cruising speed.

    Any advise would be greatly appreciated.

    THANKS & HAPPY BOATING

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  2. Capt J, Jul 9, 2010
    #2
    Capt J

    Capt J Senior Member

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    Gas engines like yours are designed to be cruised at 3200 rpms. But you can cruise them up to around 3600 if the boat rides more efficient that way.
  3. NYCAP123, Jul 9, 2010
    #3
    NYCAP123

    NYCAP123 Senior Member

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    3200 may not even get that boat on plane. Depending on how she's proped I'd guess she'll max at around 4200 (possibly up to 4600). I'd run her up to check max and cruise at 80% (old rule of thumb for an older boat) which would put it at just shy of 3400 with a push to 3600. 2200 will probably have you plowing through very inefficiently.
  4. BaySailorBill, Jul 9, 2010
    #4
    BaySailorBill

    BaySailorBill New Member

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    Thanks

    Tanks for your help. This is my first twin engine inboard and I have a little homework to get up to speed.
  5. NYCAP123, Jul 9, 2010
    #5
    NYCAP123

    NYCAP123 Senior Member

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    You've got a lot of good experience in your neighborhood. Don't hesitate to ask advice around you dock. Of course be careful about which advice you follow.
  6. Capt Fred, Jul 16, 2010
    #6
    Capt Fred

    Capt Fred Senior Member

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    Not taking any exception to the previous inputs but here is something else to consider. If you run your gasers at 3400 to 3600 they will be good for about 2000 operating hours. If you can get on a decent plan at 2600 to 2700 your engines will last upwards to 6000 hours. It is a trade of speed verses engine life. I ran my last gaser at 2700 RPM for years and the internals of the engines were good up until I sold them. The choice is yours.