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SibLim update

  • 01 Jul 2020 08:01
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    Reply # 9071227 on 4315719
    Anonymous member

    It's difficult, Oscar, and I don't know what solution Annie is going to settle on for the placement of the vane.

    My choice would have been an inclined axis vane mounted on the davits crossbeam, driving a pendulum on the outside of the lute. But Anie wanted trim tabs and a vertical axis vane.

    I couldn't see a way of putting the vertical axis vane on the davits crossbeam, well aft of the sheet blocks on the middle of the lute, particularly as there are to be solar panels mounted here.

    The two options that I can see are:

    1. Vane on the centreline with the sheet on a rope bridle across the top of the outboard motor.
    2. Vane well out on one or other quarter, with the sheet blocks at the middle of the lute.
  • 30 Jun 2020 15:10
    Quote
    Reply # 9069681 on 4315719
    Anonymous member

    Curious about the choice of vertical (axis) vane - aren't you afraid of the sheets getting tangled around it during an accidental gybe and/or how do you intend to guard against it? Wondering since I have a vertical one myself and might need some reassurance or solutions.
  • 29 Jun 2020 15:31
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    Reply # 9067495 on 9062241
    Anonymous member
    Anonymous wrote:



    Very nice engineering David, one can see why she chose you....
  • 29 Jun 2020 10:54
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    Reply # 9067044 on 9065481
    Anonymous member
    I wrote:

    By the way, can anyone remember the derivation of the name "Brownstick"? I seem to remember that it was invented by someone called Brown, but can't find any written sources to verify that. Might it be second cousin to the RAF's "joystick"?

    I've found the reference I was looking for, in:

    A.Y.R.S. Publication no. 13 page 80

    (18) A further refinement in control is the "Brownstick" (based on an original experiment by Neville Brown, Esq., in AMADIA) which enables the watchkeeper, (using one hand only, and sitting in the cockpit) to unlatch the gear, steer the yacht by turning the servo blade manually, and latch up again, all in one series of movements. 



    1 file
  • 29 Jun 2020 08:13
    Quote
    Reply # 9066863 on 9065481
    Anonymous member
    Anonymous wrote:

    By the way, can anyone remember the derivation of the name "Brownstick"? I seem to remember that it was invented by someone called Brown, but can't find any written sources to verify that. Might it be second cousin to the RAF's "joystick"?

    I tend to remember that the name and article were given to the cocoction made to stear Jim's Brown playwood made trimarans from the USA back in the 60s.
  • 28 Jun 2020 14:25
    Quote
    Reply # 9065481 on 4315719
    Anonymous member

    By the way, can anyone remember the derivation of the name "Brownstick"? I seem to remember that it was invented by someone called Brown, but can't find any written sources to verify that. Might it be second cousin to the RAF's "joystick"?
  • 28 Jun 2020 09:58
    Quote
    Reply # 9065280 on 4315719
    Anonymous member

    Uffa Fox: "Simplify and add lightness".

    Having a couple of days in hand before collection by the courier, I've actioned the second part of that dictum, and added a little more elegance as well. Mass balance and low rotary moment of inertia are important parts of a good vane gear design.

    [The sharp-eyed observer would have noticed that the top of the latch plate was scratched - most of the materials used were upcycled/repurposed/rescued from my dusty boxes of scrap. Cutting away the sides to a concave shape got rid of one of these scratches, adding even more elegance]

    Last modified: 28 Jun 2020 10:05 | Anonymous member
  • 27 Jun 2020 23:43
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    Reply # 9064751 on 4315719
    Anonymous member

    PS. Have you ever seen anything that combines simplicity with elegance so wonderfully well?  A miilion thanks to The Great One.
  • 27 Jun 2020 23:37
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    Reply # 9064733 on 4315719
    Anonymous member

    1.  If it's obsolete it works

    2.  Sailing boats aren't motor cars.  They ate much more dynamic and in a much more dynamic environment.  Apparently adjusting course 3.5° or even 7° doesn't necessarily mean that this is how far the boat will change its heading.

    3. The Brownstick also enables you to alter course temporarily, eg to avoid an obstruction or a ship, without resetting the vane gear.
  • 27 Jun 2020 18:28
    Quote
    Reply # 9064245 on 9064113
    Anonymous member
    Mark wrote:

    KISS !

    If you had a second alternative hole for the peg, half a notch out, you could adjust course by 3.5deg?

    Only if the peg is inserted manually, and the latch plate doesn't rise. Not with remote course setting, using a line to lift the whole latch and a Brownstick to nudge the latch one way or the other.

    The Aries has a similar step between its ratchet teeth.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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