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About patzefran

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    Beach cats, Trimarans

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  1. patzefran

    GPS Watch

    It is why so many gps top speed claim are unreliable, only 10 s mean velocity make sense !
  2. patzefran

    Homemade small tri

    From my experience she is not doing 19 kt here, need to provide a GPS record !
  3. patzefran

    Banque Pop capsize

    Thanks, those crazy French have re-righted Banque Populaire withou your help !
  4. patzefran

    Caribbean 600

    15 hours ago, DDW said: You do not need to guess on section and wall thickness, this is well understood engineering. There is no difference between a monohull and multihull: in each case the mast section must be large enough to withstand the maximum overturning moment the hydrostatics can produce (plus a safety factor) and no more. For a light multihull this might be less than a heavy monohull. Proa Sailor : Stayed masts on monohulls or multihulls are primarily seized for buckling under compressive loads (e.g. using Euler formula for Buckling). Maximum compressive loads are not determined by energy to capsize but by maximum righting moments (rolling and picthing restoring moments ! ) and rigging geometry. Under these aspect, as says DDW there is no difference between multihulls and monohulls.
  5. patzefran

    Caribbean 600

    Proa Sailor, You didn't even read what DDW write. He only said that Multihulls / monohulls depends on the same methodology !
  6. patzefran

    Whisper Foiling Catamaran Sailors

    I am puzzled about the low velocity recorded ! It seems a low speed foiler ? I am faster with my 15 ft floating Tri
  7. patzefran


    Team BBR, I suspect your braking effect is the fact of hydroelasticity. The farther away from the rudder pintles, the bigger the stress induced by the foil's drag and the strain on the rudder blade will induce more AoA on the fence and induced drag. As for the flow around the fence, It could be effectively faster in the vicinity of the stern of a planning hull like I14, which is not the case for a catamaran hull.
  8. patzefran


    "To get a benefit from the increased aspect ratio effect, you need the winglets on the bottom of the rudders, in a T format. This negates the "Bieker" effect." : I don't see why putting the winglet on the bottom of the rudder would negate your downward lift at 4° AOA !
  9. patzefran

    Astus Upwind

    Tom, perhaps your rudder has too much forward rake an is unstable or has near neutral stability. If this is the case, when you let the helm free even a minor blade assymmetry can induce this kind of behavior. Try to lessen your ruder rake in order to get the real feeling of your boat's behavior is, i.E. weather helm or lee helm. If your rudder has adequate stability margin, the consequences or any assymmetry should be very little and your boat should exihibit his true behavior, I.E. with sail COE aft of underwater COE it will turn to windward when you let the helm, or the opposite if the sail COE is ahead underwater COE..
  10. patzefran

    Astus Upwind

    The comparison with big tris doesn't apply. Obviously Astus has fully submersible outriggers , ORMA and Mod 70 currently fly the mainhull with 200% buoyancy outriggers. It seems also that MOD 70 recorded several capsize ! IMHO Beamier tris with full buoyancy are more prone to pitchpole only because you can push them harder / faster downwind. From my experience (Strike 15) submersible outrigger (like Astus), are less powerful and fast but much more tolerant to capsize than full buoyancy.
  11. patzefran

    SeaRail 19 Folds

    From my own experience, when I used Dyneema or Dyneema HT for the water stays of my trimarans (Strike 15 and Strike 20) I needed to retighten after each sailing. Now I use Vectran and I never need to retighten ! I will never use again dyneema for standing rigging. I use it only for sheets and halyhard.
  12. patzefran

    new trimaran under 20

    Considering the weight, relatively short mast, and 5.80 m beam, you will need plenty of wind to lift the mainhull ! my Tri is 6.10 x 5.10 m with similar weight and I need more than 15 kt to lift the main (just kissing !). I needed very strong waterstays to keep the boat stiff, and also back stays to avoid collapsing the mast (which happens to the first one !).
  13. patzefran

    Corsair Pulse 600

    Multi Thom, I agree, don't need trapeze on an olready beamy Tri. My Strike 20 is 16 ft wide and I collapsed my Tornado mast under compression loads.I needed to add backstays to manage them. to windward.mp4?dl=0
  14. patzefran

    Picked up my first cat

    Yes, if you want to waste your money :. dyneema is high resistance but stretchy ! You will need to re-tighten your rig after every sailing.. Use Vectran instead.
  15. patzefran

    Odd Weather/Lee Helm

    Sailing a Tornado in a mountain lake regatta against short dinghy with small mast, a friend was able to go straigth to the windward mark, as the other needed plenty of tacking ! Simply because his taller sail received a different wind at greater altitude. It was near Lourdes, France , of miraculous fame ! could be either a miracle or a wind artefact !