powering a 47' offshore with diesels

Discussion in 'Diesel Engines' started by Delsol, Feb 14, 2018.

  1. Delsol
    Joined: Jan 2013
    Posts: 3
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Lake Erie

    Delsol New Member

    Hello, I'm new to the forum-- but have been reading a bunch of threads and impressed by the knowledge on this site.
    I have just purchased a 47' 3 steps, and pad bottom, 9.5ft beam offshore hull. It came with 3 Arneson ASD 10/8 drop case drives. It originally had 3 1000 hp supercharged gas engines in it and achieved 106 mph.With the 3 gas engines and drives the boat tipped the scale at 22,000lbs. ,

    I am not interested in top speed but more so a nice cruise speed of 40-50 mph. I would like to achieve this with diesel engines, I have become spoiled with a 27' Munson patrol boat with Volvo 43's in it... great fuel economy and performance. I realize that it will take much more hp to propel this hull compared to my 27' but am willing to use more fuel for a more comfortable ride on Lake Erie when it kicks up.
    I have been running different scenarios through the calculator on boatdiesel.com and am surprised by some of the outcomes.
    I have run everything form 3 cummins 480hp to 2 cat c12.9 1000hp combinations... I would much rather have only the 2 engines but thought I would run the 3 through the calculator....
    I have become a bit baffled as the larger hp options are coming back with unrealistic prop options. And a top speed of approx. 55 mph.
    Does anyone have any info on the setup in say a 44' Magnum? I see they are running 800hp and achieving 55mph through the Arneson surface drives while weighing in at 33,000lbs...what props would they utilize?
    Also the 48' Fountain EC is 22,000 lbs dry and with 3 440hp Yanmars will run 65 mph. I realize that the beam is 12 ft on both of the above boats -- how much difference would that make?
    Any thoughts on what I am missing with these calculations? 2 Cummins 8.3 600hp would burn 70 gph at 50mph WOT according to the calculator -- any real world experience out there?

    Thanks for any info,

  2. Barry
    Joined: Mar 2002
    Posts: 1,830
    Likes: 474, Points: 83, Legacy Rep: 158

    Barry Senior Member

    Surface Drives | Arneson Industries http://new.arneson-industries.com/surface-drives

    You should get in touch with Arneson and ask them as they will have had hands on experience with the diesels in front of their drives and probably able to discuss props and gear ratios as well
    which is something y0u might have to change
    48 Sundancer with Arneson Drives http://www.clubsearay.com/index.php?threads/48-sundancer-with-arneson-drives.71867/

    Then try any Arneson forums. There have been several discussion points on these drives on this forum, just use the search box upper right for the links

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.