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Old 19-01-2012, 23:59   #1
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Latitude Sailing Explanation

I've heard that before precise chronometers were available, some sailors used "latitude sailing" to find their way around. I am aware that it involves maintaining a certain latitude until you bump into the desired longitude, but I want to know more about the actual processes involved to achieve this. Presumably they still needed to be able to use a sextant?
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Old 20-01-2012, 00:05   #2
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Re: Latitude Sailing Explanation

Roughly Speaking - Latitude was achievable long time before longitude (read Davd Sobel's excellent book called "Longitude) So knowing that you destination was at 12 degrees south latitude, and not being extremely sure on the whole longitude thing, ships would get onto their latitude early and sale that latitude till they hit the destination.

This is where the oft misquoted and homonym-ically tortured term Plane Sailing comes from, literally to sail the PLANE (not as is usually stated - Plain sailing to mean its easy)
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Old 20-01-2012, 00:20   #3
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Re: Latitude Sailing Explanation

In the days of latitude sailing sextants were not yet there. Instead they used latitude hooks, kamal http://en.wikipedia.org/wiki/Kamal_(navigation) , jacob's staff Jacob's staff - Wikipedia, the free encyclopedia and later astrolab and such to sail the desired latitude. There were no way except death reckoning to "know" longitude without chronometres. Basicly they sailed until bumped on the shoreline.
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Old 20-01-2012, 05:48   #4
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Quote:
Originally Posted by Factor
Roughly Speaking - Latitude was achievable long time before longitude (read Davd Sobel's excellent book called "Longitude) So knowing that you destination was at 12 degrees south latitude, and not being extremely sure on the whole longitude thing, ships would get onto their latitude early and sale that latitude till they hit the destination.

This is where the oft misquoted and homonym-ically tortured term Plane Sailing comes from, literally to sail the PLANE (not as is usually stated - Plain sailing to mean its easy)
Plane sailing comes from the mathematics of plane trigonometry as opposed to great circle spherical trig.

The term "sailing down your westing " or easting comes from latitude sailing. For example with gold returning from the Americas to Portugal , the ships would sail north to the correct latitude and then sail their easting till they hit Lisbon.

The main drawback was it was easy to intercept such convoys , one what to merely wait on the correct latitude

The Jesuits in particular were keen to develop the maths of navigation, particulary to try to overcome this problem. They founded one of the first schools of navigation in Portugal
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Old 20-01-2012, 07:36   #5
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Re: Latitude Sailing Explanation

Latitude sailing has been used in the last 150 yrs, the old time sailing directions used by west coast capitans to reach Hilo and other islands in that area, was sail 7 days west and turn left ! LOL no kidding, my grand father capitained lumber schooners from Eureka Ca to all over the Pacific, and I still remember his storys as a child Im 73 so you can see it was not to long ago folks sailed this way !! just a little history LOL Bob and Connie
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Old 20-01-2012, 08:48   #6
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Re: Latitude Sailing Explanation

There's nothing really to stop you navigating at sea this way today, esp. if you know from charts that's there's nothing rocky in the way to ruin the cruise...ahem...

It just takes longer than a circle route and you may spend time waiting for wind.
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Old 20-01-2012, 09:22   #7
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Re: Latitude Sailing Explanation

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Originally Posted by goboatingnow View Post
The Jesuits in particular were keen to develop the maths of navigation, particulary to try to overcome this problem. They founded one of the first schools of navigation in Portugal
Actually I think Prince Henry the Navigator was credited with founding the first school of navigation in Sagres, Portugal. He was the son of Joao I of Portugal and Phillipa of Lancaster. I made a pilgrimmage there when touring Portugal.

Scott
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Old 20-01-2012, 10:52   #8
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Re: Latitude Sailing Explanation

It depends on what direction you are making landfall from, but in many cases it is not much slower. You don't have to head due North or South until on the given latitude and then make a 90 degree turn East or West.

In practice you guess how far off your longitude could be, what your uncertainty is, and then make sure that you are on the correct latitude before your longitude could be right. A little dog leg is usually all you need.

With passages that are mostly East or West it does not add many miles. And in the South Pacific, at least, with East-ish tradewinds and old sailing ships that could not go to weather at all, it was better to make landfall from the East, anyways.
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