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George, a gentle "heads up": I don't live in my computer.  It may be days or 
weeks before you see a response from me.

I get it, regarding language.  I pick up a wrench and hand over a spanner.  
Sometimes I forget and hand over a wrench.  I'll try to improve my 
performance in language.

No promises regarding how my writing "sounds."  My background isn't in authoring romance novels.

I'll try to answer your questions and comments (post 10912) in order.

1. "Can a suitable place for a fluxgate compass always be found BELOW DECKS 
[emphasis mine] on a steel WARSHIP [emphasis mine], in which an automatic 
correction algorithm alone will provide sufficient heading accuracy for 
navigation, with no need for correction magnets or balls?"

I have limits, and I apologize if it appears that I've strung you along.  In 
simple terms, the "stay out of jail" card reads like this: I can talk about 
unclassified-unlimited distribution items.  The legal precedent has also been 
set so that I can talk about items that have been "leaked" into the press or 
published elsewhere, and that leads to the ethical dilemmas that "me and my 
kind" get to deal with.  That question is out of bounds, in my opinion.  
Sorry.

However, I have already stated that they were installed on all-steel ships and 
they worked.  The sensor assembly makes no real distinction between a steel 
warship and a steel commercial fishing boat or steel yacht.  Looking for 
yourself will answer the question, as I have already recommended.

2. "Were such instruments ever actually adopted as the principal heading reference?"

Not in "major" warships i.e. frigate and above.  Weapon systems reach out a 
long ways (even then).  And that's why they went away.  Today's backups are 
true.

3. "Joe has shifted the discussion toward self-steering, but that's a 
different matter, as Lu has pointed out, not requiring any great precision."

Nope, I'm encouraging you to look for yourself.  I thought "who in the 
civilian marine world uses this stuff?"  Autopilot users, and folks with 
integrated systems.  Standardized NMEA/ISO output signal leads to integrated 
systems.  You'll see that if you look.

4. "De-gaussing."  I won't copy-and-paste your entire comment (this post is long enough).

Magnetic influence mines are still in use.  Relating to the fluxgates, two 
deviation equation/tables were created: degaussing on and degaussing off.  
You can (and do) change the ship's magnetic signature "on the fly."  It's a 
good way to stay alive.

5. "If Joe's "very, very special steel" happens to be a stainless or other 
high-nickel alloy, effectively low-magnetic, I hope he will make that clear."

I inadvertently made a Navy school instructor temporarily famous.  Had a 
fellow student who was fairly intelligent but had absolutely no common sense. 
 Eventually the instructor's trip wire broke and he made a comment, and 
immediately apologized even though he was a Commander and the student was an 
Ensign.  That night I made a sign and hung it on my school desk, and I've 
hung that sign wherever I've worked.  What did it say? "Xxxxx's Idiom: some 
things are intuitive; and for that I apologize."  Xxxxx was the Commander's 
last name.  Reread the paragraphs immediately above and below the 
hazegray.org link I provided, and the link (where I told you to look), then 
engage thy brain.  If you still don't get it then I can't help you.  Speak up 
and perhaps another reader will tell you what the very, very special steel 
is.  And for that I apologize.

6. "Was this equipment used on vessels intended to operate at differing 
magnetic latitudes? If so, did operating instructions call for a 360-degree 
turn to be made, for recalibration, as the magnetic latitude changed?"

Yes to the first and no (with a caveat) to the second.  Made me think of two 
very real issues that I can't remember dealing with: 1) the Flinder's bar or 
unbalanced card effect, as in a "traditional" compass and 2) increased dip at 
high latitudes which will make the heading more uncertain.

Mr. Husick, at the following link, can explain it better than me.  On the left 
side look for the Electronic Compasses and, ummm..., Autopilots articles.  
Pay attention when he gets into the "old technology" fluxgate stuff.

http://www.boatus.com/husick/default.asp?WT.mc_id=400098

I do remember the "new instructions" called for a recalibration when necessary 
or when in doubt, deleting the "annual" requirement after they understood the 
stability of these systems.  Some ships went a couple years between 
recalibrations.  Believe it or not, the "old instructions" also called for a 
recalibration when entering restricted waters if the fluxgate was the 
"active" device (failure of primary).  Bureaucrats and theorists operate in 
their own world.  Their restricted waters had no traffic and had lots of room 
to turn a 450ft ship.  Recalibrating BEFORE entering restricted waters didn't 
count in their world.

Now to the thread-specific questions and comments in your post 10936:

1. "Sweet spot."  Hopefully this is clear to you by now, both in term 
definition and in sensor assembly location.  What do I want you to do?

2. "Armchair term."  I'm not a microbiologist or a brain surgeon, and I won't 
pretend to be one.  If you've done fleet time then I apologize for sounding 
derogatory, which wasn't intended.


George, I've said all I can say.  You really should go look for yourself.  
Bumblebees can fly.  Let us know what you learn.

Joe

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