John Deere or Cummins

Discussion in 'Diesel Engines' started by islands50, Sep 1, 2014.

    Joined: Oct 2002
    Posts: 4,519
    Likes: 110, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    >I suppose it all comes down to how much power is required to push this vessel at it's hull speed, and or most efficient speed.<

    Probably not , usually sail boats are interested in hull speed but few marine motorists chose to operate there.

    The reason is slowing about 1K can frequently save 1/2 the fuel burn.

    Most cruisers will set up to load the engine well at a very good percentage of the 24/7 curve at cruise RPM.
    If the engine can operate at 70 hp at 1400, and the boat needs 60 at SL 1.15 , thats where you want to be.

    The shorter operating hour graph can be used for heavy weather when higher HP is required to maintain speed.
    Usually high speed in a sea state results in severe motions the operators find uncomfotible , and perhaps dangerous.

    The difficult boat to engine is the oxymoron , fast trawler, that may want 20K once or twice a year .

    Then the recreational ,short time , engine load is used for the top speed desired and a compromise is required the other 98% of the time when displacement cruising.

    Usually it only calls for lighter less efficient loading at higher RPM , so the vessel might cruise at 1800 rpm where it could put out say 110 hp , but the same 60 is needed to move the boat. A fuel map can help these decisions , prop load fuel burn is useless.

    The engine size , drive and hull should match the owners desirements , although efficient fast and slow may be wanted , a compromise is required.

    Most rec boats will not pay the bucks for a CPP or other fancy way to attempt to compromise .

  2. islands50
    Joined: May 2012
    Posts: 18
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Port Lavava,TX

    islands50 Junior Member

    I have to agree with you, and everything is a compromise these days, there again we must go back to my original post, the vessel is a troller, used for fishing, using west coast style tuna / salmon gear, maybe I should have said that to start with? Other then just describing a troller and assuming people knew what that was, and again I agree with you

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.