Stability of boat if foils fails

Discussion in 'Stability' started by skatun, Mar 7, 2018.

  1. skatun
    Joined: Sep 2010
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    Location: Aachen

    skatun Junior Member

    Hi all,
    I am working on making an electric foil boat, that should fit inside a standard 40" container. This means it will be pretty long and narrow(12m*2.4m max).

    15996070_10154774124141215_434293656_n.jpg

    I have a sketch made up: 15978995_10154774086546215_849543140_n.png

    Where legs are where the hydrofoil will be attached. My question is if this design will work:
    How to get it foiling in waves?
    What will happened if foils fails, with stability in big waves?
    Can legs be used to anchor the boat if the foils are removed?

    Any input ideas would be great! Its still on and early phase.
     
  2. jorgepease
    Joined: Feb 2012
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    Location: Florida

    jorgepease Senior Member

    sounds like a pretty complex idea, is there a specific application that warrants such a boat.
     
  3. skatun
    Joined: Sep 2010
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    Location: Aachen

    skatun Junior Member

    @jorgepease
    Foiling cats are much faster or less power consumption than normal monohulls. So when going electric I would say having foil is almost the only option if you would like to achieve some kind of range with state of the art battery technology which is affordable(Tesla power wall for instance, hydrogen is to expensive..) The idea to have it to fit inside a shipping container is that you can get it produced somewhere and get it shipped to Norway, and also if you want to go on holidays in asia, you just ship the boat ahead of time.

    To fit a family of 4 you need some size and hence we ended up with 12*2.4m=30m^2. My biggest concern at time being is stability in waves and how to calculate this.
     
  4. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    The calculation does not have to differ from that of any other type of hull but it would be convenient for you to better define under what exact conditions you wish to calculate the boat and the stability criteria that you wish to meet with this boat. The L / B ratio is very high, which is not good for the initial stability (initial GMt).
     
  5. skatun
    Joined: Sep 2010
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    Location: Aachen

    skatun Junior Member

    Yes I know, and this is what concerns me, when Foiling the foil is what creates stability and hence the L/B is not an issue, its when the foil fails/ getting to foil speed that worries me. (capsizing) I am just unsure if I need to alter the design, make it quadromaran when the foils fails for instance. Back to the sketchboard :)
     
  6. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    Before changing anything, even before you have started, you should define what you want to achieve and under what conditions.
    Even with that L / B ratio, a catamaran has much greater initial stability than a monocoque, so if you do not consider more than this parameter, your design is "very stable". Is it stable enough? That can not be answered without knowing what it is, for you, "enough".
     
  7. skatun
    Joined: Sep 2010
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    Location: Aachen

    skatun Junior Member

    We want to be able to cruise in the north sea which can get some pretty bad storms coming up in short time! As an aerospace engineer I can calculate stability of the foils and hence this is not my concern, but if these fails I am a bit lost on how to proceed, and any input on where to read up on this would be great. I started looking into using openfoam and two phase flow as the tool, its however not straight forward to do this.
     
  8. jorgepease
    Joined: Feb 2012
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    Location: Florida

    jorgepease Senior Member

    I've only fished in North Sea on three occasions, waves were never less than 4 meters, it was ridiculous lol, I hope I was just unlucky ))
     

  9. Heimfried
    Joined: Apr 2015
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    Location: Berlin, Germany

    Heimfried Senior Member

    Hi skatun,

    some basic stability data and floating behaviour in different load conditions of your boat you could retrieve from a webpage of mine. Assumption would be a file containing a (3 D) set of offsets decribing your boat.

    If you are interested in it, try whith a given Kat:

    Berechnung der Schwimmlage von Booten http://www.bootsphysik.de/booteco62.php

    If you prefer English: button top right.
     
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