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    Re: Eight day aircraft clock
    From: Hewitt Schlereth
    Date: 2015 Oct 9, 16:10 -0700
    Francis, I will write to the boys in the BOL forthwith. You take the prize and the Rotary takes the cake. What is its diameter? The relative scale looks wrong on my email.


    On Oct 8, 2015, at 10:57 PM, Francis Upchurch <NoReply_Upchurch@fer3.com> wrote:

    I have a 6 year old Rotary mechanical (automatic wind) Chinese built watch (about $100 back then) with glass faces showing the internals a la an open H4.( I fanstasize it maybe an H4 while at sea) Harrison would probably have recognised most of the wirly, tick tock  bits except maybe the movement winder and the lack of bi-metalic parts .The Invar alloy, temperature and magnetic insensitive, would have amazed him no doubt and made  some of his inventions, such as bi-metallic strips, obsolete.

    3 years ago, I did a mock "Longitude prize test", 4 weeks (didn't go to Jamaica, just coastal sailing in Cornwall).

    If warn on the wrist 24/7 at sea, it lost on average 20 secs per day.If warn just a few hours and removed, tended to lose anything from 10- 50 secs per day. So presumably the constant wearing reduces variable  temperature and static positon effects and gives more constant winding?

    Anyways, a graph drawn through the 20 secs per day lost, gave me predicted rate which gave me good accuracy  after 4 weeks, well under 2 minutes out.So I claim the prize please, Longitude Board! With inflation, that would be about £3million. please pay direct into my offsore account. !

    My favourite quartz is my Citizen eco drive divers, virtually bullet proof. Generally good for +2 secs per month whatever I do with it, direct sun, sea or dropping.

    Citizen Professional Diver Eco-Drive Mens Watch BN0000-04H

    The pictures are not to scale! Roughly similar size.

    I also like to do "no clock" cel nav using lunars,bit like Slocum, using a towed log to get distance run between observations. I haven't written up my recent few experiments yet, but Longitude by lunars and no clock generally within 30 nm. most of my longitudes using the Rotary were within 5-20 nm. So the clock beats the moon, at least with my lunars at sea.

    All great fun! Greg, I think JS  Letcher used only an 8 day aircraft panel clock in the 1960s, $22 ($170 now).


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