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423 classico engines and hull design

Discussion in 'Ocean Alexander Yacht' started by Gordon J., Nov 13, 2015.

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  1. Gordon J.

    Gordon J. New Member

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    Jul 23, 2015
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    Virginia
    I have a question about the 423 classico hulls I have seen both 420 hp and 600 to 630 hp versions of this boat. Are the hulls the same? A friend tells me that he consumes only 4 gallons an hour on his 420 hp 423 at hull speed. Can I expect 4 to 5 gallons an hour at hull speed with the 600 hp engine set? I am talking about the boat equipped with the 3116 cat engines.

    Thanks in advance for all your assistance,

    Gordon
  2. Capt J

    Capt J Senior Member

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    Yeah you should burn around there at hull speed if the 3116's are running at 1000 rpms or less and you're maintaining hull speed. Should burn little more if any, running hull speed with 600hp engines also.
  3. Gordon J.

    Gordon J. New Member

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    Jul 23, 2015
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    Virginia
    Captain J.,

    thanks for the answer. Is your answer based on experience or are you merely surmising based upon your knowledge of boats in general?

    Thanks again,
    Gordon
  4. Capt J

    Capt J Senior Member

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    Experience, if there's an engine out there (relatively modern), I have probably run it and probably run it for an extended period of time. Any engine will burn pretty much the same at each RPM point, provided it's propped correctly, no matter what boat it is in. It takes a given amount of HP in each boat to achieve hull speed. For example hull speed in this boat may be 1000 rpms with the 400 hp motors, and 850 rpms with the 600 hp engines. Now above 1000 rpms (2300-2400rpm motor) when the turbo's start building boost, then fuel consumption drastically changes with the larger engines. But, keep in mind you should run them up to cruise for 30 minutes, every 6 hours or less.

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