Compass fluid
Ian Johnston
I recently acquired a very nice Sestrel Major handbearing compass.
Generally lovely condition, but there is a great big bubble in the
fluid. Can anyone tell me what to use to top it up? I have, somewhere,
a bottle of special oil for my glider's compass, but the stuff in the
Sestrel looks a lot thinner - I suspect that it's an alcohol and not
an oil.
Ian
--
Chris
"Ian Johnston" <NOianSPAM.N...@btinternet.com> wrote in message
news:cCUlhtvFIYkV-pn2-NcM9sI2zkddd@localhost...
wrong fluid and the numerals fell off inside so I am now a little more
careful.
This is probably not the correct thing to do but I managed to gently press
the diaphragm in the bottom of a steering compass and let the bubble escape
out of the vent screw which I tightened again before releasing the pressure
on the diaphragm. Worked ok for me and is virtually risk free.
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Graham Gowland
You don't think the bubbles there to allow for expansion?
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Tony of Judicious
> On Wed, 06 Oct 2004 19:18:37 GMT, "Graham Gowland"
> <gowlan...@bigfoot.com> wrote:
>
>>> I recently acquired a very nice Sestrel Major handbearing compass.
>>> Generally lovely condition, but there is a great big bubble in the
>>> fluid. Can anyone tell me what to use to top it up? I have, somewhere,
>>> a bottle of special oil for my glider's compass, but the stuff in the
>>> Sestrel looks a lot thinner - I suspect that it's an alcohol and not
>>> an oil.
>>>
>>> Ian
>>> --
>>
>>You don't think the bubbles there to allow for expansion?
>
> No. They are just badly designed. There should be a diaphragm to allow
> for expansion. There isn't.
I have one of these compasses (and a beautiful objectit is, probably dates
from the time J was new, 1964). There is a diaphram, mine developed a leak
at the diaphram seal and got a bubble.
Had it serviced by BPSC Marine - www.bpsc-marine.co.uk - for £55 and a very
nice job they did.
Ian Johnston
wrote:
: "Ian Johnston" <NOianSPAM.N...@btinternet.com> wrote in message
: news:cCUlhtvFIYkV-pn2-NcM9sI2zkddd@localhost...
: > Can anyone tell me what to use to top it up?
: I once messed up an admittedly inexpensive compass by filling it with the
: wrong fluid and the numerals fell off inside so I am now a little more
: careful.
That's what I'm scared of.
: This is probably not the correct thing to do but I managed to gently press
: the diaphragm in the bottom of a steering compass and let the bubble escape
: out of the vent screw which I tightened again before releasing the pressure
: on the diaphragm. Worked ok for me and is virtually risk free.
Good idea, but it's a b-i-g bubble, so I don't think whatever
expansion mechanism is in the Sestrel will be enough...
Ian
Ian Johnston
<gowlan...@bigfoot.com> wrote:
: You don't think the bubbles there to allow for expansion?
Nope. It's huge - the whole of the glass top is out of fluid with the
thing level, which makes it impossible to read through the prism.
Ian
--
Ian Johnston
: No. They are just badly designed. There should be a diaphragm to allow
: for expansion. There isn't.
Have you seen a Sestrel Major? The baseof the internal bowl is ribbed
and flexible for precisely this reason. And they stayed in production
for, what, fifty years, so the design can't be that bad!
Ian
Ian Johnston
<to...@deletethis.thoward.plus.com> wrote:
: Had it serviced by BPSC Marine - www.bpsc-marine.co.uk - for œ55 and a very
: nice job they did.
Thanks - I have emailed them.
Ian
--
Barleycorn
Barleycorn.
Dennis Pogson
Yes, I heard that too, Plymouth Gin is the best, more pure alcohol content.
Leave out the tonic though, and the ice and lemon.
Remove "nospam" from return address.
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Cushie
some years ago I obtained from the compass supplier (Seafarer)
Ian Johnston
: You said hand bearing compass and I thought you were talking about the
: same Sestrel hand bearing compass that I have.
:
: My old Sestrel hand bearing compass was part of a long dead Brookes
: and Gatehouse DF radio.
Ah. Maybe I am getting my terms mixed up. The one I have is about 9"
high with a wooden handle and a prism on top. I thought that was a
Setrel Major.
Ian
--
Ian Johnston
: Isn't a Sestrel Major a bit heavy to be used as a hand bearing
: compass?
I have checked (they are at http://www.sirs.co.uk/marine.htm) and you
are quite right. What I have is a Sestrel Radiant handbearing compass.
Whoops. I still need fluid for it!
Ian
--
Ian Johnston
: There are plenty of Sestrel Major photos on the web but none of a
: Sestrel Hand bearing compass that I could find.
The current version (slightly shorter handle, as it uses a betalight
so no battery storage) is at the bottom of
http://www.sirs.co.uk/marine.htm. I have just spoken to a friendly
expert at the makers, who tells me that mine - I have confirmed this
by opening the filler and sniffing - uses a 50-50 mix of industrial
methylated spirits and water. Next problem: how to buy a small
quantity of industrial methylated spirits.
Ian
:
--
Mike
"Ian Johnston" <NOianSPAM.N...@btinternet.com> wrote in message
news:cCUlhtvFIYkV-pn2-NcM9sI2zkddd@localhost...
Ian Johnston
: I have always used White Spirit to top mine up with no problems.
Apparently newer ones use Bayol and older ones use an alcohol-water
mix.
Ian
--
Ian Johnston
: On 7 Oct 2004 09:09:36 GMT, "Ian Johnston"
: <NOianSPAM.N...@btinternet.com> wrote:
: >Next problem: how to buy a small
: >quantity of industrial methylated spirits.
:
: You can buy it from your local chemist.
Not here I can't. They do normal coloured meths, but not the clear
stuff. Though somewhere I think I have a bottle of the coloured stuff
that faded...
Ian
--
Ian Johnston
: It contains 1/2 litre of "Bayol".
: ...
: So not industrial meths.
Modern ones uses Bayol, old ones use alcohol. You can tell,
apparently, by the colour of the seal under the glass.
: That seems a lot is it really so big?
The bowl is - roughly - 10cm diameter and 4cm deep, which is 314cc ...
maybe it's sold by the half litre?
: Incidentally there is no sign of an expanison chamber or diphragm in
: the diagram.
Indeed. That's because it's an integral part of 5581 Bowl Assembly.
There is an inner base with annular ridges - a bit like the aneroid
unit ina barometer - to do the expansion.
Ian
Simon Brooke
('m...@privacy.net') wrote:
> On 7 Oct 2004 08:57:42 GMT, "Ian Johnston"
> <NOianSPAM.N...@btinternet.com> wrote:
>
>>On Thu, 7 Oct 2004 08:19:47 UTC, martin <m...@privacy.net> wrote:
>>
>>: Isn't a Sestrel Major a bit heavy to be used as a hand bearing
>>: compass?
>>
>>I have checked (they are at http://www.sirs.co.uk/marine.htm) and you
>>are quite right. What I have is a Sestrel Radiant handbearing compass.
>
> That's very superior to my B&G hand bearing compass. AFAIR the prism
> was moulded into the top.
>
> It's good to see that they are still being made.
>
>>Whoops. I still need fluid for it!
>
> It's a very thin oil. Drink the G&T :-)
>
> Did you notice that the divisions on the Sestrel Major are in units of
> 5 degrees, I'm sure my Sestrel Major compass is divided into smaller
> units. Not that 5 degrees isn't sufficiently accurate.
Ian, I have a small bottle of n-decane, supplied to me by the Professor
of Chemistry at Lancaster University who kindly analysed the contents
of my Souwester Bosun compass. I can't guarantee it's right for yours,
but if yours is indeed 'a very thin oil' it will probably do. If you'd
like some, drop round sometime.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
Morning had broken, and I found when I looked that we had run out
of copper roove nails.
Ronald Raygun
What's the difference between industrial and non-industrial meths?
Is it just that the latter is purple?
What's the difference between drinking-alcohol and meths? I gather
meths is basically drinking alcohol (ethanol) with a bit of poison
(methanol) added to keep the excisemen happy (to make you go blind
or die if you drink it), and then they put some stuff in to make it
taste so foul that you -as good as- can't drink enough of it to do
you damage (to keep the excisemen even happier, i.e. out of court on
manslaughter charges).
I suggest that the mixed-in methanol is not essential for the
compass, and it should work perfectly well on a 50-50 mix of
ethanol and water. In manufacturing the compasses, they probably
use meths simply because it's cheaper than ethanol.
I further suggest that water alone would in principle be fine but
that the added alcohol gives frost protection and perhaps also
suppresses algal growth.
Also, 50-50 is probably not essential unless you wish to use the
compass in extremely cold conditions, so 40-60 should be just fine.
The obvious conclusion is, as others have said even if only in jest,
to use gin. A cheap supermarket own-brand will do, no need to splash
out on the good stuff.
Tony of Judicious
> Also, 50-50 is probably not essential unless you wish to use the
> compass in extremely cold conditions, so 40-60 should be just fine.
>
> The obvious conclusion is, as others have said even if only in jest,
> to use gin. A cheap supermarket own-brand will do, no need to splash
> out on the good stuff.
Don't dilute it as it already 37.5% alocohol.
However, whyis the bubble there in there in the first place? It should be
completely sealed. With mine it was a leak and I could smell alcohol when
I unscrewed the handle.
Ian Johnston
<no....@localhost.localdomain> wrote:
: What's the difference between industrial and non-industrial meths?
: Is it just that the latter is purple?
I think the industrial stuff lacks the dye and the odour.
: What's the difference between drinking-alcohol and meths? I gather
: meths is basically drinking alcohol (ethanol) with a bit of poison
: (methanol) added to keep the excisemen happy (to make you go blind
: or die if you drink it), and then they put some stuff in to make it
: taste so foul that you -as good as- can't drink enough of it to do
: you damage (to keep the excisemen even happier, i.e. out of court on
: manslaughter charges).
I think the smell traditionally coms from a mercaptan, just like the
LPG in my car. However, some brands now include bitrex which is there
mainy to stop children chugging it down.
: The obvious conclusion is, as others have said even if only in jest,
: to use gin. A cheap supermarket own-brand will do, no need to splash
: out on the good stuff.
Hmm. As a sanctimonious teetotal git I have none of that sort of stuff
in the house, but will ask around my friends...
Ian
Ian Johnston
: I have a WWII RAF Spitfire grid compass, bought with pocket money from
: an army surplus store in the mid-nineteen fifties. There's no sign of
: bubbles yet!
Quality stuff. The designers probably went on to do the SL400 toilet
in civilian life...
Ian
--
Ronald Raygun
Careful. They could think you've seen the light. "I need it for
my compass" just doesn't sound totally credible.
I think you'll find that a half bottle (wear disguise when buying if
necessary to protect your reputation -- ask for a discreet brown paper
bag to hide it in on the way home) contains 350 ml or a little more,
which sounds just the right amount for your requirements, with not too
much "waste" left over to have to pour down the toilet together with
what's left of the original stuff.
Ian Sandell
<NOianSPAM.N...@btinternet.com> wrote:
That sounds a lot like gin or vodka (less a bit of methanol which I
think would be neither here nor there in this application). Or use
some IPA (iso propyl alcohol - not the Green King stuff).
Ian
PyroJames
Ian Sandell <i...@sandell.co.uk> wrote in message
news:54aem01hp48ljg1u8...@4ax.com...
There was an article in YM some years ago or someone using Gin in their
compass, but IIRC it "melted" or at least caused the dome to collapse. The
maker was very sympathetic and supplied a new dome and the right fluid. I'd
check with the maker first.
--
PyroJames
The chilling wind turning over leaves and coat tails,
Dirt, syringes, running feet.