Sebastian Marie to the next level

Discussion in 'Boat Design' started by rfleet1066, Sep 21, 2020.

  1. rfleet1066
    Joined: Feb 2012
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    Location: New Kent, VA USA

    rfleet1066 rfleet1066

    The river boat, Sebastian Marie was born right here on this forum with priceless information provided by the esteemed members. She has been in the water for two years and traveled over 4000 river miles. The engineer/child in me wants to take it to the next level.
    I am designing hydraulic oar articulating units for installation at sixteen places, eight on each hull. Now, I know about the motion of an oar, but just enough to make trouble. Who can tell me about oar geometry, speed, angle,.........all that stuff?

    Ryland Fleet
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    I don't know anything about the technical details of rowing, but I am just wondering why you are now going down this route, when you have a nice big diesel engine with a long tail shaft drive propeller driving her with pretty good results?

    But a bit of googling found this paper, which might help a bit?

    Here is a link to Ryland's thread about building the Sebastian Marie -
    river boat progress
  3. rfleet1066
    Joined: Feb 2012
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    rfleet1066 rfleet1066

    Every major event in my life has led me to believe that anything is possible. It may not be a good idea, but still possible.I don't know if hydraulic oars have been done before, but I'm going there.
    bajansailor likes this.
  4. CocoonCruisers
    Joined: Dec 2015
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    CocoonCruisers Junior Member

    Not very convinced about the hydraulics: for anything i can imagine spontaneously, efficiency seems far below what can be achieved with the simple classic transmission with a lever and an almost frictionless hinge.
    But seeing (and admiring) how you tend to go for it at grand scale, here are my 2cents:
    - Even with sixteen people rowing, it's not going to move fast: the ergometers in the rowing schools show no more than about 200-300w continuous and 500w peak for untrained rowers on a very efficient sliding seat geometry.
    - Force is in the legs, not the arms. Sliding seat works nicely, but you may also want to have a look at the pedal system in one of the last america's cup boats. These were race-bike-style, but recliner-style setups are more efficient.
    - Perhaps you'll want to limit the beam for narrow parts of the river. Some ancient ships had rudders hung almost vertically from some framework.
    - Have you thought about poling instead ? Speed may be comparable and with some locking trick you'll gain the possibility to hold station against current or wind.
    Last edited: Sep 24, 2020

  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You should study mechanisms, particularly those that satisfy the Grashof Condition. There are relatively simple formulas that govern links and their movement.
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