EarthBM

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About EarthBM

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    Corona Del Mar, CA and Deerfield Beach, FL

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  1. (Reality of course is probably 1000kg and $100k more than that)
  2. I think the logical outcome of the “$$$ rule” would be that the design should be an optimal balance across multiple dimensions: - If I am indifferent between the choices of marginally increasing my LWL or beam, then the dimensions are in balance. I think it would be something like 40x34. - If I am indifferent between spending my next $10k on using more carbon in a 40ft tri or on extending LWL by 1ft then the carbon content is about optimal. I suspect this means very little CF (mast, maybe akas, or more likely just some structural components). - if I prefer spending $10k on adding ama foils to extending LWL then they belong in the design, otherwise not (I suspect not, because they probably need all carbon ama structures) - taller masts are a relatively cheap way to boost performance so probably should be limited to “tall enough” 70’ or so to avoid the death race. - T-rudders seem like a low cost performance add. Bowsprit. - rudders in the amas vs high aspect ratio vaka rudder - again cost trade off (or just owner preference) Think Class 40 monos is a good example to emulate. They are seaworthy, can be cruised, have accommodations, with reasonable limits on carbon. I would mandate 4-5 berths, minimum fresh water tank, one head, standing room in most of the cabin to increase offshore autonomy and commercial appeal (think resale values). So basically Corley’s Kurt Hughes design but with 34’ beam... if this can be made to true 2000kg displacement (I know a couple of Kurt’s tris that turned out way over designed weight) and inside $250k with sails quite a few will get sold and form a good class.
  3. EarthBM

    Near Capsize

    Nice! How did the lifeline get in the which? was the main again the spreaders?
  4. Well yeah, if a random box rule limits you lwl but not beam, more beam may incrementally increase stability. I don’t know what a good rule for a class is. Was F40 multi class successful? Mono Class 40 seems to be. I guess the best rule would be $$$ - sail (race?) with what you can spend max $100k on. and for my $$$, if I start with a square tri, adding lwl would bring the most marginal begefit.
  5. The next step is sailing my Dragonfly 35 from LA to Panama and up to Miami (or selling it and trading up).

  6. Stumbled on this topic searching for something else... On the square dimensions.. A square trimaran is not symmetrically stable because the buoyancy at the bows is a fraction of the buoyancy at the amas. So it's much easier to pitch pole it than to flip sideways. As most ORMAs have discovered. Don't think this depends on size, except that for beach cats and the Wetas the crew weight can compensate for that by sitting way aft when going downwind. If you are in the death zone, buried the leeward ama, released the main and are falling off the wind the square design feels wrong.
  7. New mast and sails coming I hear, the boat is for sale
  8. EarthBM

    Caribbean 600

    How would the windward board help? (Edit: instead of lee board! Got it!) For the leeward board I imagine it’s an advantage of curved (edit: or angled) boards — they slip more at higher heel angles.
  9. EarthBM

    Caribbean 600

    another note to self: relocate the ditch bag to the ama hatch. With big multi capsizes relatively rare, any nuggets of info are gold. Thanks!
  10. EarthBM

    Caribbean 600

    Glad the discussion is still constructive, thanks Harryproa (Rob?)! About Elvis using Fujin capsize as new information for their racing decisions -- makes perfect sense. In multi races you optimize risk taken for the odds of gusts, not prevailing winds. And the capsize tells you that the outlier gusts are more likely (tails of the probability distribution are fatter). Hard to have the real time info on the gusts. Need careful evaluation of just how variable wind speeds can get in these conditions. That the pre-race weather report was prepared by the "former navigator for Vestas Wind" gave me a superstitious sense of risk even in my comfy sofa. Reminder to self (when single handing a 35' tri): finally install cam cleats next to winches to use instead of self-tailers; pull the trigger on the wider mesh trampoline purchase; make sure to hold the leeward main sheet.
  11. EarthBM

    Tri for sale in NZ

    Why not call the seller? The phone number is there.
  12. EarthBM

    ARC 2017

    There is another ts42 in RORC Transatlantic right now, in the middle of Class 40 monos and such.
  13. EarthBM

    ARC 2017

    Yep, there have been some pretty quick doldrums crossings by the northern fleet. still, this is a more realistic representation of real world passages. If I can shave a day off a crossing by motoring for 8 hours I’d do it of course.
  14. EarthBM

    ARC 2017

    Well, we observe the difference from x1.5-x2 speed difference most people expect of multis vs monos to x1.06 actual difference vs the Swan. if not the crew then what? It just happened to be the middle wind race where the hull speed mattered?
  15. EarthBM

    ARC 2017

    There has been some discussion of how multihulls in real world cruising are just barely faster than monos. Apart from the issue that the monos in question are either 2x-5x the cost (Swan 66, Oyster 885, Nauta 885) or half the comfort (Pogo 40) the crew requirement is a major factor I think. Because multi's don't have positive stability (more heel = less righting moment) to sail close to the performance edge they need hands-on crew 24/7, ready to dump the sheets, etc. So I posit that 3-4 people can't sail a large multi at 90% on long passages, while they probably can in a mono. Which is fine.