greatest feats

The development of the chronometer in the mid-1700s made it possible to calculate longitude with reasonable accuracy, as long as one could sight the sun at local apparent noon.

 

just yesterday I read, I think it was the explorer Nansen, forgot to wind his watch/timepiece up, and that really was a big mistake because they needed it to compute the navigation....they would need that to check noontime, correct? yes, I think they couldn't compute their longitude without the watches.....whatever, navigation with blinding snow/jumbled geography/etc in the Polar regions and back really amazes me...of course, Amundsen put out markers on the way, more than Scott

 

"Reasonable accuracy" is one operative term,and the other is "local apparent time." The longer you spent between landfalls where you could fix your exact position (and thus the true longitude), the more errors crept into your dead reckoning. That's why ships sailed from one landfall to another even though it took longer to do it that way. Thus, a ship reversing the course of Shenandoah would probably take a fix at Ushant, another in the Azores, then cross to the bulge of Brazil and other known positions down the east coast of S. America, the Strait of Magellan or Cape Horn and so on. To make that perfect landfall without doing that is the greatest feat of navigation, ever.

 

It does not match Magellan's expedtions who was the first to circumnavigate the globe and the first to navigate the strait in South America connecting the Atlantic and the Pacific oceans with far less technology and facing the unknown.

 

Magellan was facing the unknown, even so he followed the coasts as much as possible. He knew that if he kept sailing west he'd circumnavigate and it mattered little if was off by 500 miles. What makes Waddel's trip unique was the pure seamanship involved to make that perfect landfall after 9000 miles without a land sighting. Nobody else has ever done that, not Magellan, not Cook, not LaPerouse.

I only bring it up because it is such an unknown feat. It was totally lost in the political furor of his dramatic appearance in the UK. What is also lost is that he too circumnavigated the globe, and captured and burned 38 American ships while doing it. And he did all that without taking a single life.

 

After surrender the CSS Shenandoah was berthed in the partially constructed Herculaneum Dock awaiting her fate. After settling the international legalities, she was turned over to the United States government



After the surrender of Shenandoah to the British government, a decision had to be made of what to do with the Confederate crew, knowing the consequences of piracy charges. Clearly many of the crew originated from the United Kingdom and its colonies and three had swum ashore in the cold November waters fearing the worst.[16]
After a full investigation by law officers of the Crown, it was decided that the officers and crew did not infringe the rules of war or the laws of nations to justify being held as prisoners, so they were unconditionally released. But the authorities of the United States considered them pirates and would have treated them as such if they had fallen into their hands.

 

How did they get through the Straights of Magellon without sighting land?

 

You did well to bring it up and his deed was indeed honorable and exceptionnal, but in my opinion there were many more daredevils before him who did different yet even more impressive feats. Vasgo de Gama, Leif Erikson, Columbus come to mind .

 

With a chronamater, a sextant, and a good e[SIZE=medium]phemeris [/SIZE]shouldn't one be able to calculate the longitude based on the relative positoins of the moon and sun or moon and stars? Possibly sun and stars as well. Not sure how accurate that calculation could be at the time but it should be enough to limit the errors due to the chronometer being somewhat off.

 

Heyerdahl's expeditions are worth an honorable mention as well IMO. The voyages that lead to the Irish settlement of Greenland shold probably rate up there as well although little is known of them.

*** I should have said Iceland instead of Greenland although I have read of possible settlements of the latter they aren't on as solid of ground ***

 

The feat was not so much "daredevil", as a feat of intellect. It pure applied seamanship which in those times was an amalgam of art, science and experience. It would be like putting somebody in a vast building hundreds of acres in extent, and even though they are allowed to memorize every turn and passage you leave a coin on the floor in one room on the opposite side and then challenge them to walk straight to it and pick it up, blindfolded. I suppose as a sailor myself, I can appreciate the difficulty better than most.

 

It just didn't work that way. Everything is estimation. How much is the chronometer off after sailing for over a year? Is the sun really at zenith, or is it a degree or two off one way or another? You can be close, but to get an exact fix you need a landfall at a known lat and long. The longer you've sailed from a known position, the more sketchy your estimation becomes. When the earlier age of exploration people "fixed" new landfalls, it sometimes took hundreds of years and many visits before all the errors were worked out. For example, Cook was the first western navigator to map much of the Alaskan coast in the 1790's (the earlier Russian maps were a mess). Yet, he got most of the lats and longs wrong even though he was a brilliant navigator. He could only estimate his positions.

 

Having been dead since 1779 might have thrown him off a bit.....

Your Waddell did a fine job bringing the Shenandoah to England, but there's no need to pretend that it was unique or miraculous.

 

They didn't go through the Straits, but sailed south and went through the sea between the tip of S. America and Antarctica.

OK, Cook mapped the coast of Alaska on his voyage of 1776-79, not not 1790. And if you find a map of any of his voyages, you'll see he went from landfall to landfall. And if you find some of his charts, you'll see he got the lats and longs wrong.

The voyage and perfect landfall of the Shenandoah was unique and somewhat miraculous. Nobody before or since has done any feat of navigation approaching it. If you don't understand naval affairs or navigation, then perhaps you should refrain from commenting.

 

I'm not suggesting the above would get you an exact longitude or allow you an exact recalibration of your chronomiter but repeated checking should allow you to put bounds on the error. What those bounds are I really don't have a good handle on. I do remember reading that standard practice called for "shooting" at least 3 stars to help limit the effect of errors.

 

Right. I don't want to belabor this, because it looks like only a few old sailors would really "get" what was involved. But, try to understand that you aren't standing on a fixed platform on solid ground, but rolling 10, 20, 30 degrees on a three masted sailing vessel holding a complex optical instrument to your eye. And you can't even see the stars or the sunset, or even the sun on a lot of days/nights. Your chronometer is off by an unknown amount because it's a wind-up device that has been running for over a year. Your vessel speed is measured by dropping a drag once or twice a day. You're being pushed one way or another by winds that you can only estimate, or currents you may not even be aware of.

Thirty five years ago I used to sit with the QM's and we'd try to get a latitude at sunset with a sextant (just for "fun") in calm Caribbean waters, which is supposedly the easiest part of all of this. Our shoots rarely were correct (we had LORAN to check) because even in this, there is a subjective element. For example, as the sun sets it becomes distorted in various ways by the refraction of the cooler air above the water. So, when is it really setting? If you're off by a few seconds, then your latitude is off. See what I mean?

 

Let's talk about navigational knowledge.

[SIZE=11pt]they basically went from the Aleutian Islands to the mouth of the Mersey totally on what was called "dead reckoning."[/SIZE]

This implies that Waddell conducted the entire voyage without ever getting a celestial fix. Is this really your contention? Any competent seaman gets a fix whenever he can. Dead reckoning is what you do between fixes. In those days, bad weather might prevent him from sighting the sun or stars for days, even weeks, but as soon as conditions permitted, Waddell or any other navigator would take sightings and compute his position. He might compare it to his dead reckoning track to estimate how currents or leeway were affecting the ship, and if he was still in the same currents or winds he might incorporate that into the new DR track which he would start from the position of the fix.

[SIZE=11pt]longitude is just an educated guess based on estimated vessel speed, known currents, movement to leeward from the wind and so on. [/SIZE]

That was largely true prior to the development of the chronometer, although of course currents and winds don't just affect a ship's east-west position. And yes, chronometers were not perfect, and they had to kept wound, but longitude in the 1800s was well beyond being "just an educated guess". There were also complicated ways of computing longitude from celestial sightings, although they were less practical for shipboard use.

 

No, it's not my contention and if you think so then either my writing or your reading comprehension leave much to be desired. Obviously, you're here to pick nits on a subject you know nothing about. A celestial fix doesn't give you a latitude and longitude, and a chronometer was a wind-up device that had to be checked and corrected every time you had made a landfall at a known longitude. All of the tools of the mariner at that time had a subjective element and that's why mariners depended on landfalls to correct their dead reckoning. Even a short(ish) voyage across the Atlantic was made via landfalls. If you were going from Europe to New York or Montreal you'd shoot for a landfall at Newfoundland even though it might take you hundreds of miles out of your way. To do otherwise might find you on the rocks on the north American coast a dozen miles off your course on some dark night.
If going further south, you'd shoot for the Azores and then Bermuda, for the same reasons. Each landfall allowed you to verify or correct your navigation.

 

much thanks all replies, I learn a lot in so little time and space...very interesting all

 

Of course it does. You have to do the calculations and plot them, which I've done, I was an officer in the Navy thirty years ago too, but the whole point of celestial navigation is to fix your position on the earth.

Since you're so obsessed with Waddell, perhaps you should dig up his log and see how often he records taking fixes and establishing his position. If it actually says he used dead reckoning the whole way, I will be honest enough to acknowledge it.