HOW TO FIND LONGITUDE WITH YOUR VIKING SHIELD


http://www.sjolander.com/viking/sketches/shield/body /
I enjoyed the thread on plywood armour so much, decided to post something more in the same vein.
Everyone already knows that Viking shields were made with wood. Doesn't everyone? Well, if you didn't, you do now. So, I'm not posting shield plans.
I hope that as soon as you finish your longitudef inding shield you will post pictures. I'll be waiting with bated breath.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The recommended method quickly gets into trouble. A swinging pendulum on a moving boat, with pitch, roll and yaw accelerations, isn't a reliable measure of time. See: Longitude : The True Story Lone Genius Who Solved Greatest Scientific Problem his Time by Dava Sobel.
Steve

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 01 May 2005 18:28:29 GMT, Steven and Gail Peterson

I thought the Vikings sailed by latitude alone, hoping their food would last until they got to Nova Scotia (whichever name they called it)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Charles Krug wrote:

While they didn't have the compass, they did have a Sun compass which would tell them where North was during the day. it was a sundial used in reverse.
They didn't really sail by latitude becasue they had no angular measurement instrument to tell them what latitude they were on. The Arabs did (Kamal), but the Vikings hadn't seen that.
--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The Vikings had made it at least as far as Constantinople. I would have guessed they had seen the kamal.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mon, May 2, 2005, 4:56am (EDT+4) snipped-for-privacy@foo.bar (MichaelDaly) The Vikings had made it at least as far as Constantinople. I would have guessed they had seen the kamal.
Probably. But, as I understand it, a kamea was used to determine star positions. Sun compass and kamal were supposedly developed around the same time, anyway. Both used to determine latitude. Basically, they would head north, or south, until they got to the latitude of their destination, then turn, and sail to it - simple, effective. Longitude wasn't able to be accurately determined until the 17th century.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
J T wrote:

The Kamal was used to determine whether or not you had reached a latitude. It is essentially a piece of wood with a hole in the center. In this hole was a string - stopped at one end. You can see a picture of one on my web page below.
You pre-calibrated it at your destination:
You held it up to your eye and moved it out until the bottom edge was on the horizon and the top edge was on, say, the North star. you place a knot in the string such that that was the distance the kamal was from your eye when you held the knot behind yoru front teeth.
Now it's calibrated for that destination. You cna put a knot in fro several.
So when you left a port and headed TO one of those destinations, you ran North or South until the North Star and horizon was lined up with that knot behind your teeth. Then you hung a left or right to get into port. If the run was a long one you kept checking to be sure you maintained that latitude.,

the Sun Compass was not used to determine your latitude, as I understand it. it was used to figure out which way was North. It was essentially a sundial used in reverse.

Agreed with the above paragraph.

--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mon, May 2, 2005, 4:53am snipped-for-privacy@comcast.net (gregg) says: <snip> the Sun Compass was not used to determine your latitude, as I understand it. it was used to figure out which way was North. It was essentially a sundial used in reverse. <snip>
Easy enough to find north without any gadgets. The Sun Compass was used to determine True North, which is a bit trickier. And, apparently was "set" for a specific latitude. So, if you wanted that latitude, you could use a Sun Compass to find it. Another latitude, another Sun Compass. Supposedly is was within a few degrees as accurate as a magnetic compass - which is not bad for those times.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
J T wrote:

At sea? During the Day?

I have to disagree - the Vikings weren't aware of magnetic variation. They had no magnetic compass. They didn't know there was True vs Magnetic North.

It was marked out at a specific latitude, yes. They had no math to mark the Sun Compass out without using the sun in the first place. So, like the Kamal it was calibrated for latitudes.

How? What actions were taken with ta sun compass to determine your latitude?

--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tue, May 3, 2005, 4:57am snipped-for-privacy@comcast.net (gregg) advises: At sea? During the Day? <snip> They had no magnetic compass. They didn't know there was True vs Magnetic North. <snip>
Yeah, at sea, during the day. You wait until the sun is at it's highest, you look at a shadow, the shadow points north. Then you point, and say, "Hey, that way's north". Simple. However, not exactly precise. The Vikings didn't need to know about "True North", what they needed was a consistent reference point, this allow them to have just that.
Toward the end of the Viking age, they did have access to magnetic compasses.
Check this. http://members.aol.com/jvlambert/Norman/SunCompass.htm
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
J T wrote:

You conveniently snipped the essential part of the question. You said they used the Sun compass to find variation.
Tellme how they used the Sun compass to find the variation.
Yes they DID use it to find True North - but that's what I've been telling you for 2 days now

--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
J T wrote:

No.
You snipped out the REAL question that was posed to you. But here it is:
You said:

To which I asked:

Explain to me HOW they found Norht WITHOUT ANY GADGETS...
Bear in mind that the Viking Sun Compass is...a GADGET.
Next you said:

Trickier than WHAT? I've been telling you that the Vikings used the Sun compass to find North, now for two days. The "North" it finds is True North. It's not "trickier"...it's only "trickier" to find True North *IF* you are using a magnetic compass.

--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tue, May 3, 2005, 6:02pm snipped-for-privacy@comcast.net (gregg) burbled: No. You snipped out the REAL question that was posed to you. But here it is: You said: Easy enough to find north without any gadgets. To which I asked: At sea? During the Day? Explain to me HOW they found Norht WITHOUT ANY GADGETS... Bear in mind that the Viking Sun Compass is...a GADGET. Next you said: The Sun Compass was used to determine True North, which is a bit trickier. Trickier than WHAT? I've been telling you that the Vikings used the Sun compass to find North, now for two days. The "North" it finds is True North. It's not "trickier"...it's only "trickier" to find True North *IF* you are using a magnetic compass.
Nah, I answered the "real" question. You just ignored the answer. I said (and you copied it): "Yeah, at sea, during the day. You wait until the sun is at it's highest, you look at a shadow, the shadow points north. Then you point, and say, "Hey, that way's north"." See. Simple, no gadgets. A bit vague perhaps, but still north.
Yup, the Sun Compass finds what everyone is calling "True North", didn't need you to tell me that. But, I never said anything about using a Sun Compass to find north, I said look at "a" shadow, then point. You apparently took that to mean using a Sun Compass. Nope, shadow, finger. But pointing is a tad vague. Could be 10, 20, or more degrees off, depending of degree of sobriety, whether the arm was waving, and so on. That's the "no gadget" method. Of course the Sun Compass is a gadget. So's a viking ship, so's a shield, so's a kamal, you could call anything people use a gadget.
Perhaps you would have understood if I'd said "more accurate", instead of "trickier", or maybe you're just nit-picking. It's always easier to point out a direction with your finger (no technology involved, so not tricky), than to use a gadget (involves technological device, so tickier) fo find precise direction.
If you're using a compass, and want to find "True North", simple enough. All you have to do is know how many degrees away from magnetic north it is. Or, not be bothered with it at all. Anyway, most of the time the Vikings were reputed to sail within sight of land, and usually only ventured out of sight of land when they were blown off course.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
J T wrote:

Explain to me how you know the Sun is at it's highest....without a gadget...
you look at a shadow, the shadow points north. Then you point,

WHICH IS USING A GADGET...which is in direct contradiction to what you said:

The Viking Sun Compass is not a gadget?

No I'm trying to make sense of what you are saying which is very difficult.
--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm thinking this thread is getting bogged down. I think you should all go back and read the site again. Four years to complete it? Count every other pendulum swings from noon to noon? Then that number of swings is the time from noon to midnight? Yah, right. First that would assume the count was started, and ended, at true noon. And, the counter didn't lose count, etc., etc., and a lot of other stuff.
Whan I found the site, I read it. Then read it again. Then I started ROTFLMAO. It all might work on dry land, but on a ship, at sea? I don't buy it. Personally I think it's all just a big joke.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Michael Daly wrote:

Well yes but that was late in the "Viking Age" as I recall.
But when they made their voyages West, it was without anythign but a Sun Compass.
--
Saville

Replicas of 15th-19th century nautical navigational instruments:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sun, May 1, 2005, 6:28pm (EDT+4) snipped-for-privacy@earthlink.net (StevenandGailPeterson) burbled: The recommended method quickly gets into trouble. A swinging pendulum on a moving boat, with pitch, roll and yaw accelerations, isn't a reliable measure of time. See: Longitude : The True Story Lone Genius Who Solved Greatest Scientific Problem his Time by Dava Sobel.
Hmmm. I would suggest you go back to the link, and reread it very carefully. Then think about what you read.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
How to find longitude with this shield. While sailing, longitude may be found in the following manner:
1. Find noon to find midnight. Using a piece of wood with a straight hole bored in it. This hole would need to be large enough so that the Vikings could sail as far north as they wished and the hole would still let daylight pass thru at the noon hour. This piece of wood needs to be suspended such that the hole is at 90 degrees to the center of the earth. In other words, the piece of wood needs to be flat with the surface of the earth. However since we are on a heeling boat, we can not just lay this piece of wood on the deck. I think suspending it by three strings would do. Held by a person so as to dampen all rocking motion on the piece of wood.
Thus to find noon with this hole we need to start counting as soon as any sun starts to pass thru the hole. Then stop counting when the sun stops passing thru the hole. Half way between these two times is exactly noon.
Now to use this information to find midnight is as follows. When the sun starts to shin thru the hole, the man of the watch starts to count EVERY OTHER SWING of the pendulum. Thus the number of swings counted is exactly the count from noon to when the sun stops passing thru the hole. Which is exactly what we want. Now to continue. When the sun stops passing thru the hole the man on the watch starts to count EVERY SWING of the pendulum. He continues this count until he reaches his midnight total count.
end quote
This clearly depends on the use of a pendulum to measure time, which is the problem that prevented anyone from determining longitude until Harrison invented a clock that was sufficiently accurate and stable, free from inaccuracy due to ship motion. His invention allowed the British a great advantage in marine navigation, both Naval and commercial, until others figured it out too.
Steve
(Steven and Gail Peterson) burbled: The recommended method quickly gets into trouble. A swinging pendulum on a moving boat, with pitch, roll and yaw accelerations, isn't a reliable measure of time. See: Longitude : The True Story Lone Genius Who Solved Greatest Scientific Problem his Time by Dava Sobel.
Hmmm. I would suggest you go back to the link, and reread it very carefully. Then think about what you read.
JOAT A highbrow is a person educated beyond his intelligence. - Brander Matthews
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.