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Re: [boatdesign] Re: a question about rudder angle

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  • L
      Damn.  So somebody DOES read this crap!    -L ... rudder. Done.Again, thanks, everyone; this is entertaining.Curtis--- In
    Message 1 of 36 , Feb 12, 2013
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      Damn.  So somebody DOES read this crap! 

      From: Bradley Davis <davisbr9@...>
      To: boatdesign@yahoogroups.com
      Sent: Tuesday, February 12, 2013 10:57 AM
      Subject: Re: [boatdesign] Re: a question about rudder angle
      ... "whizzbangery" sounds like some new British dance-fad which is sweeping the States. Or an upcoming Valentine's Day rendezvous with a loved one. Giggidy!
      The point is, I love it. It's useful. And fun, with a hint of whimsy. Well done!
      On Tue, Feb 12, 2013 at 10:55 AM, Bradley Davis <davisbr9@...> wrote:
      I'd just like to say one thing: "modern techno-nav-whizzbangery" is about the funniest thing I've read all day, and I plan to use it in the near future. Mostly because the phrase contains "whizzbangery," which can be adapted to pretty much anything which requires more than "it's magic" as an explanation.
      Thanks! Brad
      On Tue, Feb 12, 2013 at 10:32 AM, L <lew_clayman@...> wrote:
      The French Revolution tried a decimal calendar.  The population understood immediately how that decreased the weekends by about a third, so it was massively resisted.
      The year, the month, and the day don't work out neatly - it's a fact of astronomy, the cycles don't divide each other evenly.  If you try to force the year into a whole number of days, you ALWAYS have some leftover fractions to deal with.  Unless the earth changes either its orbit or its daily rotation, that's just how it is.  Figuring the moon into it (really important in the days before artificial lighting) only makes it worse.
      About the best we can do is to agree on some arbitrary standard calendar (Gregorian) and some arbitrary unit of time (the standardized second as defined with reference to the "official" atom - no kidding).  All of which is quoted WRT an arbitrary point on the earth, UTC.  And we're good to go, or as close as we're ever likely to get (maybe something will replace the official atom, that's about it really).
      In fact, the earth does change its orbit and daily rotation.  It just happens very slowly and continuously - but it does require a "leap second" every few years.  Thanks to the internet, everybody gets the leap second automatically within a few minutes and unless you catch a news item about it you'll probably never know - it "just happens" on your cell phone or GPS etc next time it checks the time with The Big Clock In The Sky (or is it in Switzerland?).
      The stars and (arbitrary) constellations appear to track exactly to the day and year, but this is an illusion.  It's caused by the fact that they move so slowly WRT the earth and sun that they appear fixed for long periods, but as the earth rotates and "wobbles" they seem to change position accordingly.  Still, they are close enough to fixed that you can steer by them reliably.  Any jiggle on your end is far larger than the sloooowwww precession on their part.  (Ah but the planets - they're another story altogether.)
      Oddly enough, astrology DOESN"T track the constellations.  It's all calculated on their fixed position at some selected point back in history.  No idea why.  But if you were born "under" Aquarius (say) then it's unlikey that Aquarius was really in the "over" spot that night.  No idea why, don't care either.  But it's NOT EVEN with reference to the stars on the day of your birth... it's to their positions, on that day in some selected prior year, that day as figured on the Gregorian calendar.
      Boatdesign relevance?  Well, celestial navigation for starters.  And even GPS and kindred modern techno-nav-whizzbangery all speak in terms familiar from prior technologies.  And yes, going back to Babylonia, if not far earlier.
      Also history: fun boaty fact - Columbus landed on October 12, 1492 Old Style.  October 12 Gregorian DOESN'T mark the anniversary on the calendar that Columbus (or anybody else at the time) used.

      From: john colley <Helliconia54@...>
      To: "boatdesign@yahoogroups.com" <boatdesign@yahoogroups.com>
      Sent: Tuesday, February 12, 2013 5:37 AM
      Subject: Re: [boatdesign] Re: a question about rudder angle
      Azimov possited a Digital calendar that fixed all problems,but one.THAT extra day.He got rid of that by making it a "NON" day.That is New year day, separate from the calendar.My head is aching,

      "There is magic in the feel of a paddle and the movement of a canoe, a magic compounded of distance, adventure, solitude, and peace."-Sigurd Olson
      From: L <lew_clayman@...>
      To: "boatdesign@yahoogroups.com" <boatdesign@yahoogroups.com>
      Sent: Monday, 11 February 2013 7:10 AM
      Subject: Re: [boatdesign] Re: a question about rudder angle
      Why sync them up?  The sun and moon don't sync up worth a damn, nor do the earth-day and the earth-year, and near as anybody can tell the week has no naturalistic basis whatsoever.

      This is why every calendar system ever invented on earth ends up having some kind of leap year or else just gives up on one piece or another (eg the Romans gave up on the moon, and invented months that aren't lunar anymore... the Muslims gave up on the sun and use a year that isn't solar anymore) - becomes they don't have ANY useful common denominators.

      (It's possible that the week is really a case of trying to use quarter-moons, but they gave up on it and went to a non-lunar quarter-month.)

      Unless you mean, how to sync your alien calendar to the usual earth Gregorian calendar.  You can drive yourself to distraction, or you can take a lesson from people who, right here on earth, use two different calendars routinely.  That would include Chinese of all faiths and none; as well as Hindus, Muslims, Jews, and Orthodox Christians... in other words, the vast majority of all humans.  No kidding. (Oh, and anybody of any faith or none living in nations - or even neighborhoods - with heavy majorities of any of those.)

      It's actually pretty easy, ask me offline.  Done it my whole life.  If it's driving you to distraction, you're doing it wrong.

      From: Curtis <clmanges@...>
      To: boatdesign@yahoogroups.com
      Sent: Sunday, February 10, 2013 2:04 PM
      Subject: [boatdesign] Re: a question about rudder angle
      Good guesses, Peter -- these aliens do have four digits on their hands, so they use base-eight arithmetic (everyone counts on their fingers, right?). They have a 14-month year and an eight-day week, and follow a lunar calendar. I drove myself to distraction synchronizing events in two calendar systems. They also have three moons, so their tide tables are - interesting, although the outer two are small and don't usually do much.And, yes, internal combustion, a recent refit from a "wood-burner," but their level of technology -- at least until they meet humans -- is mostly steam and a little electricity. Rural folks live like Amish.Lew, I've never gotten as far as figuring out how they measure angles (or weight, for that matter). Some details would bore anyone but a small number of hard-core readers.Anyway, I figured out a better way to bypass the whole measurement issue with the rudder angle -- I just had the guy turn the wheel for one-eighth left rudder. Done.Again, thanks, everyone; this is entertaining.Curtis--- In mailto:boatdesign%40yahoogroups.com, L wrote:>> Degrees, as Peter  said, are indeed an integer multiple of our base, ten.  But the 360-degree circle is also, more originally, an integer multiple of the Babylonian mixed-based system of 12's and 60's.  So is our daily clock, strangely enough.> > > But the numbers 12 and 360 might instead be the source of the mixed bases than the other way around, or it could be a co-development now lost to antiquity.  The number 360 was an early and approximated/stylized version of the count of days in the year - the "circle" of the seasons.  Of course it was arguably stylized by forcing it into a multiple of our base.  The number 12 approximates the lunar cycles in the year - the months, simplified/stylized to 30 days.> > My point is that Peter is correct - aliens would not necessarily base anything on ten fingers; but neither would they base anything on the earth and our sun.> > I can never decide if it's impressive and cool, or depressing and discouraging, that we're still using Babylonian math - the Babylonian year, hour, minute, and second.  Of course we also use the Roman months and the Israelite week, so let's not obsess about the Babylonians alone.> > You just know the aliens wouldn't! > > -L> > > > >________________________________> > From: Peter > >To: mailto:boatdesign%40yahoogroups.com it> >Subject: [boatdesign] Re: a question about rudder angle> > > >> >  > >> I could have handled it differently; the characters are aliens, > >> and use different angular measurements, but that explanation > >> would have distracted from the passage.> >> >All the aliens I know use angular measurements based on what we call radians. > >> >Otherwise, it depends on anatomy. For obvious reasons, any empirical systems (as opposed to a math-derived system like radians) is going to have an even number for a right angle, so it's going to be a multiple of the base of their numbering system. We have 9 times the base, or 90 degrees. > >> >In Toonville, where all the characters have just three fingers and a thumb, they use octal numbers. That works out well for them because they can set 100 (= 64 in decimal) octo-degrees for the full circle. Then {0,10,20,30,40,50,60,70} octo-degress ( = {0,8,16,24,32,40,48,54} in decimal) are the 10 octal (8 decimal) points of the compass.> >> >Sorry to say, I'm not a sci fi fan. I know that SF authors spend a lot of time developing plausible other societies. Some spend so much time on it, I don't know how they get the time to actually write anything.> >> >So, is this boat driven by an internal combustion engine? How boring.> >> >> > > >> >>
      Bradley Davisdavisbr9@...
      Bradley Davisdavisbr9@...
    • Nels A
      As you probably know Phil Bolger has used end plates very successfully on several of his designs. He writes about them in his book Boats With An Open Mind. I
      Message 36 of 36 , Mar 8, 2013
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        As you probably know Phil Bolger has used end plates very successfully on several of his designs. He writes about them in his book "Boats With An Open Mind." I think he first used one on his Tiny Cat. It improved rudder control a lot on the old traditional catboat "barn door" rudder design. And the chapter on it explains why he felt it worked well. Catboats were notorious for bad steering control downwind.


        Then he tried them on his Micro series. The Micros have inboard rudders so a deep rudder that can be raised doesn't work with an inboard rudder. This also allows the OB to be mounted on the centreline of the transom and in-line with the rudder. And the rudder (and motor) are protected by the shallow keel forward.  An inboard rudder is also an advantage on his  Micro Navigator allowing one to steer the boat from inside the cabin with a shorter tiller.

        His original Micro plans did not have an end plate but now has been added and it did improve performance. But all these are flat-bottomed hulls so I think you are correct  Graeme - probably not as effective on a vee bottom. And I think also work better in a design with more displacement . The inboard rudder is further forward and in deeper water than one hung off the transom, so is more effective even going downwind.

        Jim did design one hull called Eisbox that has the exact same rudder system as Micro - at the insistence of the person who commissioned it. But it had no shallow keel forward so needed a skeg ahead of it for protection. This meant the draft would be more and Jim doesn't like a hull with more than 4-5 inches of draft at most, so withdrew the plans for sale. I really liked the design and managed to convince Jim to haul out the mylars and send us some.  


        --- In boatdesign@yahoogroups.com, "graeme" <graeme19121984@...> wrote:
        > http://www.jimsboats.com/1may11.htm
        > I was reading where Jim Michalak said he had trouble not rounding up when running DDW with a shoal low aspect rudder with endplates. He fitted larger and larger endplates but without effect - the issue remained. He scrapped the rudder, fitted a deeper high aspect one, and fixed the trouble that way. He wrote he never went back to shoal rudders / endplates, and he has stuck with deep rudders since.
        > Now surely past a certain point there is nothing to be gained by increasing the size of endplates - except an increase likely in wetted area drag... Endplates is endplates - to reduce losses at the foil tip. Why not test increasing rudder area before condemning/rubbishing low aspect rudders and endplates?
        > Also, the issue was on one boat only. Short, wide, and deeply V'ed. The rudder may have been in surface layer water flowing with the boat on a run - dragged behind the V. The issue with any size endplate tried went away with broad reaching - perhaps leeway introduced some cleaner water flow to the rudder?
        > Graeme
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