Passive fin stabilisation of fast catamaran

Discussion in 'Stability' started by groper, Jul 22, 2015.

  1. Givitago
    Joined: Dec 2015
    Posts: 13
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Western Australia

    Givitago Junior Member

    OK here it is my ride control foil assist idea.
    I just really want to know if i was onto something and from trawling this site the last few days seems to be some very clever cookies of their respected field's around here.
    If i want to protect the idea i will have to motivate, invest and develop.

    Keep in mind this is concept there is no technical data, as told by my chook scratching s rather than trying to describe the concept.

    Foils,fins or tabs are at set degree angle of attack for lift, HYD or electric actuators deploys fins more or less for desired uplift, HYD system includes accumulators if fins strike FOD can bounce retract. Unit can be cutaway section of hull mounted or rectangular cassette mount for removal and standard section replaced for maintenance, tuning, or catastrophic failure no hull penetration. just HYD or elec connectors. this could be retrofit to existing hulls and retracted for trailer use. Electronic controlled and pilot override trim-able.

    Hulls would be as thin as possible for wave piercing but deeper for at rest 0 speed displacement also providing extra height at speed. Very sharp entry coming back to thin flat bottom planning area and outboard leg friendly with motor HYD depth adjustable
    I visioned this as 6m aluminium cat for rough weather work at speed(Pulling my cray pots in any weather).
    Size of foils/fins determine by boat fitted to. Length width, and placement.
    there are lots a details to be determine by design an engineering but all doable i think. I see these being retro fit to any hi speed hull even mono's at different degrees of attack, its all about the surface area of foil in contact instead of adjusting the surface angle of foil. adjustable drag effect, adjustable speed effect, turning lean into corners the list of advantages goes on. software would adjust to sea state, speed, top speed, stability and rudder input
    Is it a foil, fin, tab, chine, ski, deflector plate i don't know.

    Maybe been done before maybe not, i have not seen anywhere yet. So now its out there for comment.
    Once again sorry if this is too far off subject and can be moved.
     

    Attached Files:

    Last edited: Dec 8, 2015
  2. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,033
    Likes: 360, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Slimming those hulls down is going to be a problem if you want to carry any sort of load, givitago. And you better have 30" leg engines, or risk drowning them.
     
  3. Givitago
    Joined: Dec 2015
    Posts: 13
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Western Australia

    Givitago Junior Member

    Thanks E as mentioned HYD motor/outboard depth adjustable. Thin hulls is an issue and hope the added depth in hulls to offset reduced width, also the foils to offset load at speed. Ride height,angle and pitch controlled by the software. Years of cat hull design have resulted in the norm for a reason, i am asking the effect of the change in hull.
    More looking for feedback in feasibility of the foil arrangement using adjustable surface area compared to adjustable foil angle.
     
  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,033
    Likes: 360, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    There may also be problems with your foils running in aerated water, givitago, which is something a hydrofoil expert might offer an opinion on. I think foils on power cats are under-utilised, but I doubt drastically slimming the hulls will have happy results, especially running in stern quartering situations, without much to lift the lee bow.
     

  5. BMcF
    Joined: Mar 2007
    Posts: 967
    Likes: 45, Points: 28, Legacy Rep: 361
    Location: Maryland

    BMcF Senior Member

    We've been involved in the build and test of a couple small-waterplane foil-assisted vessels and they ended up working quite well. One was a very slender monohull with amas to keep it stable when operating off foils.

    As for the use of exposed foil area for lift control instead of trailing edge flaps or variable AOA, that's a concept we've looked at with some interest over the years but only played with to a very limited extent yet. We are currently testing a 63-foot loa demonstration craft that has bow foils that are "some of both"; they deploy/retract like a folding knife but also have actively-controlled trailing edge flaps.
     
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.