Reprint from Sheet&YardArm.Com chat board, July 1487:

Topic: Magnetic needles

Posted by: The Galloping Genoan
Jul-10-87 2:57 P.M. (GMT)
Hi guys! Thinking 'bout sailing west for 6 weeks to reach china,
wonder if I should buy one of those magnetic needle things. What do
you guys think about 'em?
Thanks,
Cristobal

Posted by: Old Salt
Jul-10-87 4:13 P.M. (GMT)
You damn fool! Sail west, huh? You'll fall off the friggin' earth that
way, idgit!
Fernando

Posted by: Southron
Jul-10-87 5:31 P.M. (GMT)
Hey, Cristobal, what's up. Prince Henry was asking about you the other
day. Yeah, those needles can come in handy, as long as you don't sail
too near any iron motherlodes, and as long as you don't lose all your
heavy parchment patches, and as long as some clumsy tar doesn't trip
over the box and smash it all to smithereens. Better not neglect your
star charting, odds are you'll need before it's all over.
SYOTO,
Bartolomeu

Posted by: Whale Belly
Jul-10-87 6:37 P.M. (GMT)
Cristobal, your obviosly a reel smart guy who can apprecate this so
let me share a secret with you. Dont tell nobody becuz I dont have
enough of these for everbody. When you get out there on ye waves whats
ye biggest thing you got to fear? Falling over, right? Capsizing, they
call it. Well I've got ye invention that will make that worry a thing
of ye past – its two specilly treated whale bellys that you
attach to ye sides of your ship and fill full of air. That way you
cant tump over! Ye inflated bellys keep you uprite in any see! I call
them "sponsons" and if you'll just stop by Plymouth on ye way out I'll
get you all fixed up for a very resonabil price.
Sir John

Posted by: Coaster
Jul-10-87 9:14 P.M. (GMT)
Hey, Gallop, how long you been sailing anyway? I'm guessing you're a
rank beginner by the way you talk. You sound like a moron. It's pretty
clear you know nothing of the sea. WTF do you want to go out in the
middle of the ocean for anyway? It's guys like you that give this
sport a bad name. I bet you don't even wear a PFD! I ought to let you
go on and get killed but my conscious won't let me. So let me give you
a piece of advice – don't go out of sight of land! You can have
plenty of fun right along the coast there without endangering
everybody and making people afraid of the sea by going out there and
getting killed.
Alfonso

Posted by: The Galloping Genoan
Jul-11-87 5:48 A.M. (GMT)
Thanks for the advice, Bart – sounds like I'd better get some
spares. And what's the deal with passing iron mountains? What happens
there, and how close do you have to be?
What did Prince Henry say? He wasn't very nice last time I saw him.
And to you other jerks – I'm asking about needles, could you
please stay on topic?
Thanks,
Cristobal

Posted by: Old Salt
Jul-11-87 6:24 A.M. (GMT)
Friggin' dago, you still here? GO AWAY NEWBIE! Portugal rules the
seas.
Fernando

Posted by: Whale Belly
Jul-11-87 6:36 A.M. (GMT)
If all I cared about was mysef I wudnt say anoter word after that
insult but I'm just trying to save a few lives here. Your not ye only
one reading this tread ya no. So when your drowning there besides your
capsized ship and thinking, "I wish I had sponsons now" maybe somebody
else will lern from your errors.
Sir John

Posted by: Weevilly Biscuits
Jul-11-87 7:45 A.M. (GMT)
Ye needle can be an invaluable aide, but don't let it take ye place of
common sense. Ye sun riseth in ye west, sailing west is easy. But it
does get dark and ye sky gets covered with cloud, so I always carry a
needle too.
On ye question about ye iron, I don't know a lot but I can share my
experience. In ye north sea there's an iron island. When I pass within
3 leagues of it ye needle points to ye island, turning toward it and
following it as I pass so you would think I was sailing in a circle.
At 6 leagues ye needle moves in ye island's general direction but only
a quarter or so. At 12 leagues ye effect is very small. So, in my
experience, you have to be pretty close for it to matter.
Francis

Posted by: Private Land Owner
Jul-11-87 8:37 A.M. (GMT)
Cristobal, let me ask you, when you're sailing off in the lonely seas
and you come up on a beautiful island, are you planning to land and
traipse about the place? Stealing water and wood and tracking your
muddy boots everywhere? Is that what you have in mind? Because if it
is, I just want to point out that you'll be TRESPASSING and you'll
deserve to be hung from the highest ... (CONTINUED 926
more lines)

Posted by: Southron
Jul-11-87 10:15 A.M. (GMT)
Prince Henry just asked where you were, said he hadn't seen you in a
while. What's up? You two have a spat?
On the motherlodes, Biscuits is right, you have to be pretty close.
How close depends on the size of the lode. You remember the Saint
Teresa Mountain on the coast of Africa? That one must have a lot of
iron, that one bends my needle from 30 leagues off. The main thing is
don't rely on the needle alone – check the stars and sun and
moon and make sure they agree.
SYOTO,
Bartolomeu

Posted by: Pequatcha
Jul-11-87 10:24 A.M. (GMT)
Any iron nearby will bend the needle. I heard from my father that the
way Eannes discovered Madeira was that a sailor set a bucket of nails
beside the box where Eannes set up his float and needle. He thought he
was sailing to Morocco.

Posted by: Coaster
Jul-11-87 10:34 A.M. (GMT)
Moron, this is on topic – are we not talking about the sea?
Safety first – think how your irresponsible actions can affect
others.
Alfonso

Posted by: Neptune
Jul-11-87 10:36 A.M. (GMT)
Cristobal, what kind of ship are you sailing? I hope it's not a
Coleman.
Pedro

Posted by: Whale Belly
Jul-11-87 11:31 A.M. (GMT)
It's not too lait to save your life, Cristobal. Remember: sponsons =
safty.
Sir John

Posted by: The Galloping Genoan
Jul-11-87 2:57 P.M. (GMT)
Thanks for the help, guys. Bought two needles today, with four float
boxes and four big parcels of parchment. Ready to set out as soon as I
can find some backing. Bart, Prince Henry turned me down flat on this
westward crossing. Do you know anybody up in Spain I could talk to?
Thanks,
Cristobal