motor and waterjet model

Discussion in 'Propulsion' started by franklou, Apr 17, 2018.

  1. franklou
    Joined: Apr 2018
    Posts: 4
    Likes: 0, Points: 1
    Location: singapore

    franklou New Member

    I just noticed this interesting design. This 8m boat uses a waterjet to drive it at 10 kn, not a typical design. Why so slow? Can someone help to identify the motor and waterjet model of this RAICHO design? What are the green and gray components on each side of the jet?
    Thank you!
    [​IMG]
    [​IMG] [​IMG]
     
  2. Ad Hoc
    Joined: Oct 2008
    Posts: 5,532
    Likes: 226, Points: 63, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    The writing on the cable says - i think
    Temporary installation cable...it is in Japanese!

    For an 8m boat going slow..far too many questions and not enough info really. Firstly this is what it could have been designed to do!
     
  3. franklou
    Joined: Apr 2018
    Posts: 4
    Likes: 0, Points: 1
    Location: singapore

    franklou New Member

    The thing is, is it efficient to use a waterjet at such speed? why not a propeller?
    Secondly, do you know some supplier who provides small waterjets?
     
  4. Ad Hoc
    Joined: Oct 2008
    Posts: 5,532
    Likes: 226, Points: 63, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Franklou

    Well, you need to understand the SOR to answer those questions.

    If you have been asked to supply a small boat that can run in extremely shallow water, carry big loads and so only need to do 8-10knots....what would you select....a prop...oh but it'll get damaged all the time. Oh..what can i use then?...hmmm..well a waterjet works in very shallow waters, why not use a waterjet.

    So is a waterjet efficient at 8-10knots...no. Is it ideal for extremely shallow water, no matter how efficient it is, so long as it does the job..then yes.

    You need to understand the SOR before you wish to look at one individual item on a boat to review its efficacy. Which is pointless anyway as a boat is greater than the sum of its individual parts.
     
  5. Yellowjacket
    Joined: May 2009
    Posts: 495
    Likes: 48, Points: 28, Legacy Rep: 447
    Location: Landlocked...

    Yellowjacket Senior Member

    Could be numerous reasons for going to a waterjet... You may want to not chop someone up if they fall overboard. May want very shallow draft. May be operating in rocky rivers where a prop would get destroyed... Unless you know the requirements you can't judge...

    Edit....Ad hoc was posting while I was writing.. saying the same thing...
     
  6. franklou
    Joined: Apr 2018
    Posts: 4
    Likes: 0, Points: 1
    Location: singapore

    franklou New Member

    Thank you both! Definitely we need to examine the operational profile when designing a new ship!

    BTW, are you aware of established suppliers of small waterjet? I am interested for driving a boat of about 12m at low speed.
     
  7. baeckmo
    Joined: Jun 2009
    Posts: 1,039
    Likes: 97, Points: 48, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    BTW, are you aware of established suppliers of small waterjet? I am interested for driving a boat of about 12m at low speed.

    ...small, in what sense? A propulsion device is selected on the basis of operating requirements, as thrust, maneuvrability aso, within the operational envelope.
     

  8. franklou
    Joined: Apr 2018
    Posts: 4
    Likes: 0, Points: 1
    Location: singapore

    franklou New Member

    based on the data I collected, a 50-60kW electric motor will probably suit our need. I have not got the hull form yet, so I have to wait a bit to start my calculation and plan the propulsion system.
     
Loading...
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.