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#11
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But, as you well know, the magnet(s) cannot be place at the center
of the card because that is where the bearing resides. Therefore, it follows that the magnet is off center favoring whatever side of the card minimizes the weights placed opposite of it to compensate for dip. Are your southern hemisphere compasses built the opposite of northern hemisphere compasses with respect to magnet and weight placement? S.Simon "The_navigator©" wrote in message ... I'm sorry I don't really understand the question. Dip is generally corrected by weights. So take a northern compass south and card tilts and develops a dip error. The dip in the south is gernerally in the opposite direction to that in the north if you like to think about it that way. Cheers MC Simple Simon wrote: This magnet also has a north pole that aligns itself opposite of the Earth's poles. Does a southern hemisphere compass, in order to minimize card dip, have the magnet placed the opposite direction on the south side of the card? S.Simon "The_navigator©" wrote in message ... You are correct. The dip would throw the card off and might be a problem. In fact some tasco binocs with built in compass sold here did not work for the reason! No compass seeks the pole(s). They just align themselves with local field. If you look at a large scale chart with variation the lines can often wander a great deal (let alone the local anomalies). Cheers MC Simple Simon wrote: Since the north magnetic pole is not resting upon the surface of the Earth compasses made for Northern Hemisphere use are usually weighted on the card on the southern side to keep the card more level as the north side of the card seeks out the north pole buried well inside the Earth. Are the compasses you Australian and New Zealand ******s use weighted any differently? What if you were going to sail to Canada or something. Would your southern compass work in the Northern hemisphere? Also does you compass really seek the North magnetic pole or is it made backwards to seek the south magnetic pole. Enquiring minds want to know . . . S.Simon |
#12
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The magnets can be placed either side of the bearing so the sapphire
bearing is free of mechanical obstrction. The weight is placed on the other (N on card) side in the southern hemisphere Cheers MC Simple Simon wrote: But, as you well know, the magnet(s) cannot be place at the center of the card because that is where the bearing resides. Therefore, it follows that the magnet is off center favoring whatever side of the card minimizes the weights placed opposite of it to compensate for dip. Are your southern hemisphere compasses built the opposite of northern hemisphere compasses with respect to magnet and weight placement? S.Simon "The_navigator©" wrote in message ... I'm sorry I don't really understand the question. Dip is generally corrected by weights. So take a northern compass south and card tilts and develops a dip error. The dip in the south is gernerally in the opposite direction to that in the north if you like to think about it that way. Cheers MC Simple Simon wrote: This magnet also has a north pole that aligns itself opposite of the Earth's poles. Does a southern hemisphere compass, in order to minimize card dip, have the magnet placed the opposite direction on the south side of the card? S.Simon "The_navigator©" wrote in message ... You are correct. The dip would throw the card off and might be a problem. In fact some tasco binocs with built in compass sold here did not work for the reason! No compass seeks the pole(s). They just align themselves with local field. If you look at a large scale chart with variation the lines can often wander a great deal (let alone the local anomalies). Cheers MC Simple Simon wrote: Since the north magnetic pole is not resting upon the surface of the Earth compasses made for Northern Hemisphere use are usually weighted on the card on the southern side to keep the card more level as the north side of the card seeks out the north pole buried well inside the Earth. Are the compasses you Australian and New Zealand ******s use weighted any differently? What if you were going to sail to Canada or something. Would your southern compass work in the Northern hemisphere? Also does you compass really seek the North magnetic pole or is it made backwards to seek the south magnetic pole. Enquiring minds want to know . . . S.Simon |
#13
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Thanks.
It sounds like you know of which you speak. It sounds like a northern hemisphere compass would not work too well in the southern hemisphere just as I thought and for the reasons I suspected. Poor Oz was clueless as are the greater percentage of subscribers here. S.Simon "The_navigator©" wrote in message ... The magnets can be placed either side of the bearing so the sapphire bearing is free of mechanical obstrction. The weight is placed on the other (N on card) side in the southern hemisphere Cheers MC Simple Simon wrote: But, as you well know, the magnet(s) cannot be place at the center of the card because that is where the bearing resides. Therefore, it follows that the magnet is off center favoring whatever side of the card minimizes the weights placed opposite of it to compensate for dip. Are your southern hemisphere compasses built the opposite of northern hemisphere compasses with respect to magnet and weight placement? S.Simon "The_navigator©" wrote in message ... I'm sorry I don't really understand the question. Dip is generally corrected by weights. So take a northern compass south and card tilts and develops a dip error. The dip in the south is gernerally in the opposite direction to that in the north if you like to think about it that way. Cheers MC Simple Simon wrote: This magnet also has a north pole that aligns itself opposite of the Earth's poles. Does a southern hemisphere compass, in order to minimize card dip, have the magnet placed the opposite direction on the south side of the card? S.Simon "The_navigator©" wrote in message ... You are correct. The dip would throw the card off and might be a problem. In fact some tasco binocs with built in compass sold here did not work for the reason! No compass seeks the pole(s). They just align themselves with local field. If you look at a large scale chart with variation the lines can often wander a great deal (let alone the local anomalies). Cheers MC Simple Simon wrote: Since the north magnetic pole is not resting upon the surface of the Earth compasses made for Northern Hemisphere use are usually weighted on the card on the southern side to keep the card more level as the north side of the card seeks out the north pole buried well inside the Earth. Are the compasses you Australian and New Zealand ******s use weighted any differently? What if you were going to sail to Canada or something. Would your southern compass work in the Northern hemisphere? Also does you compass really seek the North magnetic pole or is it made backwards to seek the south magnetic pole. Enquiring minds want to know . . . S.Simon |
#14
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The first answer was the closest. Yes there is a difference and yes in most
compasses including the one's we find on our sailboats and powerboats are, in fact, different. Some compasses, such as the one on USNS Bob Hope, are built to be self adjusting when crossing the line. On a previous ship one of our main bridge compasses (magnetic not gyro) showed a marked tilt some degrees south of the equator. It was recalibrated in Darwin, Australia. Great seafood buffet place down there by the way. Smaller less expensive compasses do not have this ability for self adjustment and this includes those in the many hundreds of dollars category. No need since most boats don't make it across the equator one way or another. The easiest way to solve the issue is order up a compass from some company in Australia, NZ etc. and have it airmailed. Get the exact same compass you already have. When crossing the equatorial region at some point you will observe the tilt or dip. Switch compasses and re-swing. Not hard to do even way out there. In fact I think it was Ole Thom who first gave me an explanation on how to determine exact bearings out of sight of land. This phenomenae does not happen exactly at the equator. The reason it happens is the distance from the mass of iron in N. Canada that is the Magnetic Northern Pole increases while the mass of earth's iron making up the Magnetic Southern Pole decreases in distance. At some point one becomes the major attraction to ye olde compass instead of the other and it becomes off-balance. Here's the humorous part. When the compass on our ship acted up none of the highly trained and experienced deck officers realized what had happened. One of the other AB's remarked to me, "Southern Dip?" "For sure", sez I. Finally we were asked what we meant by that phrase. They didn't believe us and had to look it up in Bowditch. Score one for the home team! Three more days and we're outta here. OT is running 4 plus hours a day and tomorrow for T-Day we will work about 12. You all enjoy the turkey . .. I'm loving the paycheck! Here's one for you. The new Chief Mate on board has the unlikely name of Despot.She just finished being Captain of a smaller vessel and is now qualifying in the big ones. Yes, I did say 'she'. Imagine "Captain Despot" being your boss. Haggie, Katy, LP don't worry about ole Neale . . . .Your gender is more than holding it's own in the commercial mariner's world. The best part is it's no longer necessary out here for someone to say, "How do you find working for a woman?" The question never comes up. But it's kinda fun knowing I work for a 'Despot'. Few more days and I'll talk to you all in two months or so . . . . MST |
#15
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Great and informative post. Thanks. It's nice to see some
people around here are more interested in providing in- formation instead of only trying to belittle and build up their own sagging egos (Oz). Your observations pretty much confirm my suspicions about compasses and nobody's mentioning dip in their world cruises. It also confirms what I know about deck officers like those who frequent this group - they know little about what we sailors know instinctively because we are so close to the water and the real world in comparison. Fair winds to ya. Enjoy your mission. S.Simon "Schoonertrash" wrote in message ... The first answer was the closest. Yes there is a difference and yes in most compasses including the one's we find on our sailboats and powerboats are, in fact, different. Some compasses, such as the one on USNS Bob Hope, are built to be self adjusting when crossing the line. On a previous ship one of our main bridge compasses (magnetic not gyro) showed a marked tilt some degrees south of the equator. It was recalibrated in Darwin, Australia. Great seafood buffet place down there by the way. Smaller less expensive compasses do not have this ability for self adjustment and this includes those in the many hundreds of dollars category. No need since most boats don't make it across the equator one way or another. The easiest way to solve the issue is order up a compass from some company in Australia, NZ etc. and have it airmailed. Get the exact same compass you already have. When crossing the equatorial region at some point you will observe the tilt or dip. Switch compasses and re-swing. Not hard to do even way out there. In fact I think it was Ole Thom who first gave me an explanation on how to determine exact bearings out of sight of land. This phenomenae does not happen exactly at the equator. The reason it happens is the distance from the mass of iron in N. Canada that is the Magnetic Northern Pole increases while the mass of earth's iron making up the Magnetic Southern Pole decreases in distance. At some point one becomes the major attraction to ye olde compass instead of the other and it becomes off-balance. Here's the humorous part. When the compass on our ship acted up none of the highly trained and experienced deck officers realized what had happened. One of the other AB's remarked to me, "Southern Dip?" "For sure", sez I. Finally we were asked what we meant by that phrase. They didn't believe us and had to look it up in Bowditch. Score one for the home team! Three more days and we're outta here. OT is running 4 plus hours a day and tomorrow for T-Day we will work about 12. You all enjoy the turkey . .. I'm loving the paycheck! Here's one for you. The new Chief Mate on board has the unlikely name of Despot.She just finished being Captain of a smaller vessel and is now qualifying in the big ones. Yes, I did say 'she'. Imagine "Captain Despot" being your boss. Haggie, Katy, LP don't worry about ole Neale . . . .Your gender is more than holding it's own in the commercial mariner's world. The best part is it's no longer necessary out here for someone to say, "How do you find working for a woman?" The question never comes up. But it's kinda fun knowing I work for a 'Despot'. Few more days and I'll talk to you all in two months or so . . . . MST |
#16
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"Simple Simon" wrote in message ...
Since the north magnetic pole is not resting upon the surface of the Earth compasses made for Northern Hemisphere use are usually weighted on the card on the southern side to keep the card more level as the north side of the card seeks out the north pole buried well inside the Earth. Ever see a chart of the magnatic field of the earth? Seems to me the weight used to hold the card level-upright is effected by gravity not magnetics. Are the compasses you Australian and New Zealand ******s use weighted any differently? What if you were going to sail to Canada or something. Would your southern compass work in the Northern hemisphere? Also does you compass really seek the North magnetic pole or is it made backwards to seek the south magnetic pole. What I want to know is: Do seashells grow clockwise in the s. hemisphere? How about barley twist canes? And in the S. Hemisphere will you Neil swirl your ceder bucket the other way?. Joe MSV RedCloud .......With a Counter Clock wise flushing head. Enquiring minds want to know . . . S.Simon |
#17
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Why clutter up the newsgroup with stupid expletives
if you don't know the answer? BRBR Got that right, bro. There is something about this Newsgroup that seems to evoke the worst in people.... Pity. |
#18
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I was just trying to respond to what I thought was a genuine
request for information. I just can't stop myself trying to help those seeking information... BRBR Please keep it up, it's refreshing and appreciated. |
#19
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Actually, he's the one who started it. Before you make
judgements, do some research. "Hmseconomy" wrote in message ... Why clutter up the newsgroup with stupid expletives if you don't know the answer? BRBR Got that right, bro. There is something about this Newsgroup that seems to evoke the worst in people.... Pity. |
#20
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Not likely from him....
"Hmseconomy" wrote in message ... I was just trying to respond to what I thought was a genuine request for information. I just can't stop myself trying to help those seeking information... BRBR Please keep it up, it's refreshing and appreciated. |
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