Southern Hemisphere Compass - Worth it?

"Alan Street" <agstreet@nonono_san.rr.com> wrote in message
news:061220051602078125%agstreet@nonono_san.rr.com ...

> Inclination, or dip, is what causes the compass card to tilt as you
> move from high latitudes to the equator. This doesn't cause an error in
> heading, but it can prevent the compass card from spinning freely.

Once again, I may be showing my ignorance but how is that dip any different
from what I could cause by holding the compass in a non-level orientation?
In that case, I just level it myself. Isn't that the solution in this case?
I could see a problem if the compass was mounted in a fixed position on a
ship but it ain't too stable on my console anyways!

In article <scSdnatba6vgsQvenZ2dnUVZ_vudnZ2d@adelphia.com>, David Gintz
<dgintz@gmail.com> wrote:

€ "Alan Street" <agstreet@nonono_san.rr.com> wrote in message
€ news:061220051602078125%agstreet@nonono_san.rr.com ...
€
€ > Inclination, or dip, is what causes the compass card to tilt as you
€ > move from high latitudes to the equator. This doesn't cause an error in
€ > heading, but it can prevent the compass card from spinning freely.
€
€ Once again, I may be showing my ignorance but how is that dip any different
€ from what I could cause by holding the compass in a non-level orientation?
€ In that case, I just level it myself. Isn't that the solution in this case?
€ I could see a problem if the compass was mounted in a fixed position on a
€ ship but it ain't too stable on my console anyways!
€
€

You would think so, but I have a wrist mounted compass that's a real
pain in the ass to use outside of it's intended zone. Yes, I can hold
my arm tilted ~20 degrees, but if you're swimming in really poor viz
and using the compass continuously for navigation, it's gets to be a
pain pretty quickly.

Alan Street <agstreet@nonono_san.rr.com> pounded away at his keyboard
resulting in:
:but if you're swimming in really poor viz
:and using the compass continuously for navigation, it's gets to be a
ain pretty quickly.

I solve that problem by simply not diving in really bad viz.

Dan Bracuk
If we don't succeed, we run the risk of failure.

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Dan Bracuk wrote:
> Alan Street <agstreet@nonono_san.rr.com> pounded away at his keyboard
> resulting in:
> :but if you're swimming in really poor viz
> :and using the compass continuously for navigation, it's gets to be a
> ain pretty quickly.
>
> I solve that problem by simply not diving in really bad viz.

In some conditions, it can be pretty easy to get 'turned around' and
lose your natural orientation, even if you have good viz.

One example is if you're photographing a turtle, as their natural
instinct is to respond to what they perceive as a predator by swimming
a curved route around the 'threat', and the net result (and photo
technique) is that the UW photographer can do a small circle while the
turtle swims larger circles around him. After 2, 3, 4, ... 6 circles,
you may find that whatever natural navigation bearings you had,
particularly if its a reef that you're not previously familiar with,
are trashed. And of course, your buddy is named Murphy, and he was
following you instead of paying any attention to navigation.

In any event, difficulties in needle float due to Inclination
variations can alternatively be addressed by not mounting the compass
on your wrist.



-hh

In article <1134258823.534144.151840@g49g2000cwa.googlegroups .com>, -hh
<recscuba_google@huntzinger.com> wrote:

€ Dan Bracuk wrote:
€ > Alan Street <agstreet@nonono_san.rr.com> pounded away at his keyboard
€ > resulting in:
€ > :but if you're swimming in really poor viz
€ > :and using the compass continuously for navigation, it's gets to be a
€ > ain pretty quickly.
€ >
€ > I solve that problem by simply not diving in really bad viz.
€
€ In some conditions, it can be pretty easy to get 'turned around' and
€ lose your natural orientation, even if you have good viz.
€
€ One example is if you're photographing a turtle, as their natural
€ instinct is to respond to what they perceive as a predator by swimming
€ a curved route around the 'threat', and the net result (and photo
€ technique) is that the UW photographer can do a small circle while the
€ turtle swims larger circles around him. After 2, 3, 4, ... 6 circles,
€ you may find that whatever natural navigation bearings you had,
€ particularly if its a reef that you're not previously familiar with,
€ are trashed. And of course, your buddy is named Murphy, and he was
€ following you instead of paying any attention to navigation.
€
€ In any event, difficulties in needle float due to Inclination
€ variations can alternatively be addressed by not mounting the compass
€ on your wrist.
€
€
€
€ -hh
€

It's a DIR thing

Alan Street wrote:
>
> It's a DIR thing

Yup, one that makes you unnecessarily buy more gear than you really
need. Film at 11.



-hh

"-hh" <recscuba_google@huntzinger.com> pounded away at his keyboard
resulting in:
:One example is if you're photographing a turtle, as their natural
:instinct is to respond to what they perceive as a predator by swimming
:a curved route around the 'threat', and the net result (and photo
:technique) is that the UW photographer can do a small circle while the
:turtle swims larger circles around him. After 2, 3, 4, ... 6 circles,
:you may find that whatever natural navigation bearings you had,
articularly if its a reef that you're not previously familiar with,
:are trashed. And of course, your buddy is named Murphy, and he was
:following you instead of paying any attention to navigation.

If you were doing dead reakoning nav on the way to the turtle, the
compass now has no use whatsoever. No sense carrying it.

But, since you mentioned turtles, you have your observations andI have
mine. Every turtle I have seen that appeared threatened just
straightlined the heck outta there.

Dan Bracuk
If we don't succeed, we run the risk of failure.

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Dan Bracuk wrote:
>
> But, since you mentioned turtles, you have your observations andI have
> mine. Every turtle I have seen that appeared threatened just
> straightlined the heck outta there.

IIRC, you've done some diving in Cozumel ... was this there, or
elsewhere?


FWIW, sometimes it seems that turtles will be jumpy and easily spooked
- and sometimes, there's a reason why: they caught a couple of illegal
turtle poachers on Cayman Brac this fall.


-hh

"-hh" <recscuba_google@huntzinger.com> wrote in message
news:1134349700.005639.285260@g49g2000cwa.googlegr oups.com...
>
> Dan Bracuk wrote:
> >
> > But, since you mentioned turtles, you have your observations andI have
> > mine. Every turtle I have seen that appeared threatened just
> > straightlined the heck outta there.
>
> IIRC, you've done some diving in Cozumel ... was this there, or
> elsewhere?
>
>
> FWIW, sometimes it seems that turtles will be jumpy and easily spooked
> - and sometimes, there's a reason why: they caught a couple of illegal
> turtle poachers on Cayman Brac this fall.

I too have noticed that they'll do a bit of a turn and then they take off.
I even had one come along to swim with me. We hung out for a while. He
kept reaching over to take a bite of something, whether it was my hair or my
reg hoses, I dunno. I never did let him get quite close enough to find out
what he was after. (Belize)

I had another one coming straight for me and I held as still as I could to
see how close it would get. Unfortunately, some other clown got ansty and
made a ruckus, which scared it away.(Belize in mating season)

In Sipadan, they didn't seem to mind us at all and we could get very close
to them. There were so many of them, that eventually, we started to look
past them to see what else we could see.



>
>
> -hh
>

"-hh" <recscuba_google@huntzinger.com> pounded away at his keyboard
resulting in:
:IIRC, you've done some diving in Cozumel ... was this there, or
:elsewhere?

Last week in Little Cayman, they sort of hung around until they were
sick and tired of the flashes and then they swam away. In a straight
line more or less.

I'll have pictures ready for public viewing soon.

Dan Bracuk
If we don't succeed, we run the risk of failure.

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