NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Nocturnal used to find time if HW.
From: John Huth
Date: 2011 Dec 27, 17:55 -0500
From: John Huth
Date: 2011 Dec 27, 17:55 -0500
With the diurnal tides, that works pretty well. On the west coast, say, in Puget Sound, I'm not sure it works so well with semi-diurnal tides. I tried to construct a similar chart for Puget Sound and found it wanting.
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Keeping up with the grind
One of my favorite local examples are the tides at Newport and the tides at Boston. High tide in Boston is pretty close to the lunar transit, while low tide in Newport is close to the lunar transit.
The tidal system for Nantucket Sound and Long Island Sound is curious. The flood comes in from the south and floods both east into Nantucket Sound and west into LI Sound. There's even a curiosity where at the southern tip of Monomoy Island, the flood tide actually flows east into the Atlantic, which seems a bit bizarre at first blush.
Also, with a lot of constrictions in LI and Nantucket Sound, some decent currents are created.
On Tue, Dec 27, 2011 at 5:16 PM, Hewitt <hhew36@gmail.com> wrote:
My 1939 Bowdich has a table of luni-tidal intervals for many ports around the world. I found it worked real well for the US East Coast, and included it in my coastal nav book. Hewitt
Sent from my iPadThe was a pretty common way of finding tides. Almanacs would describe the lag or advance between MP of the moon and the tide. In some cases, ports would be clustered by the location of the moon (NW, SW, SE, E etc) when high tide occurred, and then the timing was given in terms of days after the new moon.Some students in my class constructed replicas of nocturnals and tested them out.On Tue, Dec 27, 2011 at 6:18 AM, Keith Lindsay <kw.r.lindsay@gmail.com> wrote:
This nocturnal was made by Hunfry Cole of London in about 1575. To find the time of HW you also have to know the 'Establishment of the Port'. References in this paper have a table of lunitidal intervals.
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Keeping up with the grind
Keeping up with the grind