Podded propellers for low power range

Discussion in 'Pod Drives' started by ANAND SANKAR, Nov 29, 2016.

  1. ANAND SANKAR
    Joined: Aug 2016
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: INDIA

    ANAND SANKAR New Member

    Im working on a pleasure boat design of 14 m length, since space is a major constraint i thought of providing podded propellers which is an efficient propulsion system and does not require a seperate steering gear and hence reduce space.
    Where can i find podded propellers with small power from 20-30 KW?
     
  2. Joakim
    Joined: Apr 2004
    Posts: 880
    Likes: 45, Points: 28, Legacy Rep: 422
    Location: Finland

    Joakim Senior Member

    Yanmar has a rotating saildrive. I don't know, if you can find it on their site already, but it was at METS and has already been used a couple of years in Jeanneau sailboats.

    It has quite small lateral area and may not work well without a rudder. At least propeller thrust is needed for steering at low speeds. It was introduced for joystick steering system. Not for replacing a rudder.
     
  3. mydauphin
    Joined: Apr 2007
    Posts: 2,166
    Likes: 50, Points: 48, Legacy Rep: 575
    Location: Florida

    mydauphin Senior Member

    Some kind of rudders or rudder like keel is need otherwise boat will crawl sideways. You may have thrust but boat will get turned around by wind.
     
  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,828
    Likes: 180, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    I can't imagine a lot of applications in this hp range where an outboard motor wouldn't do the job, a whole lot cheaper, and with the option to raise the drive when needed.
     
  5. ANAND SANKAR
    Joined: Aug 2016
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: INDIA

    ANAND SANKAR New Member

    The design is actually a steel houseboat with two tiers and the total weight and power required was estimated as 50 tonnes and 38 KW (at speed of 6.4 knots) respectively
    i can provide a propeller diameter of 750 mm(max) if i use two inboard engine of 20KW and the usual shaft and propeller assembly. But if i provide outboard engines, the maximum diameter available at 20 KW is only 250-350mm, which would increase the overall power required drastically to 75KW.
     
  6. Joakim
    Joined: Apr 2004
    Posts: 880
    Likes: 45, Points: 28, Legacy Rep: 422
    Location: Finland

    Joakim Senior Member

    All sailboats and similar true displacement motorboats are such applications. Sure they can use an outboard and it is much cheaper, but with many drawbacks like poor reverse, fuel economy and charging. Also they are noisier and in many designs the propeller will be out off water in heavy seas.
     
  7. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,828
    Likes: 180, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    But you said you wanted pods ? Pods would worry me if there is a strong risk of grounding, unless there is some other grounding protection in play, to keep them out of strife.
     

  8. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,828
    Likes: 180, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Of course it depends on the application, but where once there was little use for outboards, they are now an option in some cases because of four-stroke economy, extended drive legs, better gear ratios, more suitable props, etc.
     
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.