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+--- Thread: Limb to use- Upper or Lower? (/showthread.php?tid=20)
Limb to use- Upper or Lower? - Fred_B - 12-16-2015
When using an AH it seems the Lower Limb shots are the ones I usually make because I can add quicker than subtract when using the Altitude Correction Tables. If the LL isn't available then the Upper is the only choice.
Do any of you shoot super-imposed? If so, why do you use it?
FB.
RE: Limb to use- Upper or Lower? - LouisC - 12-18-2015
I have made many superimposed Sun sights with an AH. Why? Because the lake I was using as an AH had a light breeze blowing on it and the water rippled so much selecting an UL or LL was not going to be satisfactory. Then gave superimposed Sun a few tries and was surprised how close of an intercept resulted.
RE: Limb to use- Upper or Lower? - EdCa - 12-18-2015
Mostly I use the LL when on the hard. It's easier to reduce for me. Just a preference.
RE: Limb to use- Upper or Lower? - Rdutton - 12-26-2015
(12-16-2015, 05:26 PM)Fred_B Wrote: Do any of you shoot super-imposed? If so, why do you use it?
FB.
Fred,
I shot the cloud obscured Sun super-imposed yesterday at around UT 16:32 and then did a LL sight.
Both yielded good LOPs. The super-imposed sight only needs a correction for refraction and I use the formula;
0.96 / Tan(Ha)
Shooting super-imposed is not a shot I often make using an AH.
Why do I use it? It's an easy sight.
Roland
RE: Limb to use- Upper or Lower? - BigBill - 03-18-2017
Old thread but here's my opinion.
I use an AH and prefer to superimpose the images, partly because then I don't have to do the u/l limb corrections, partly because I can never remember which is upper or lower with the AH and partly, as has been mentioned to 'average' out the effect of the rippling of the water, lol.
RE: Limb to use- Upper or Lower? - EdCa - 03-18-2017
(03-18-2017, 04:47 PM)BigBill Wrote: Old thread but here's my opinion.
I use an AH and prefer to superimpose the images, partly because then I don't have to do the u/l limb corrections, partly because I can never remember which is upper or lower with the AH and partly, as has been mentioned to 'average' out the effect of the rippling of the water, lol.
That's a good idea, BigBill. Using the same method I only correct for Refraction and IE but never parallax as it's too small to make much difference.
Making an AH that's covered is pretty simple. CelNav57 made one-
Here- Artificial Horizon
I had one made by Davis Instruments made of plastic. It's rather junky and a nuisance too work with.
Ed
RE: Limb to use- Upper or Lower? - BigBill - 03-20-2017
(03-18-2017, 05:32 PM)EdCa Wrote: That's a good idea, BigBill. Using the same method I only correct for Refraction and IE but never parallax as it's too small to make much difference.[quote pid='255' dateline='1489858376']
Making an AH that's covered is pretty simple. CelNav57 made one-
Here- Artificial Horizon
I had one made by Davis Instruments made of plastic. It's rather junky and a nuisance too work with.
Ed
I use a Davis AH, as mentioned it can be a pain in the butt. IN my case I use it often on my deck so my walking or the dogs moving about is the main culprit. It is generally more accurate than my bubble sextant though.
[/quote]
RE: Limb to use- Upper or Lower? - CarlosPindle - 03-21-2017
BigBill,
Have you tried placing it on the railing of your deck or directly over the deck's beam?
It's messier but have you tried using oil instead of water?
Carlos
RE: Limb to use- Upper or Lower? - Guest - 03-22-2017
Diesel oil is perfect and messy.
RE: Limb to use- Upper or Lower? - BigBill - 03-22-2017
(03-21-2017, 10:06 PM)CarlosPindle Wrote: BigBill,[quote pid='266' dateline='1490133976']
Have you tried placing it on the railing of your deck or directly over the deck's beam?
It's messier but have you tried using oil instead of water?
Carlos
No, it's just practice anyhow so the mess isn't justifiable. The rail is just as unsteady. That being said if I'm patient everything settles down eventually. I figure if I can get decent sights this way, it could be an analog to a boat, lol.
[/quote]
RE: Limb to use- Upper or Lower? - P.Rutherford - 03-22-2017
(03-22-2017, 09:33 PM)BigBill Wrote:(03-21-2017, 10:06 PM)CarlosPindle Wrote: BigBill,[quote pid='266' dateline='1490133976']
Have you tried placing it on the railing of your deck or directly over the deck's beam?
It's messier but have you tried using oil instead of water?
Carlos
No, it's just practice anyhow so the mess isn't justifiable. The rail is just as unsteady. That being said if I'm patient everything settles down eventually. I figure if I can get decent sights this way, it could be an analog to a boat, lol.
[/quote]
Diesel oil is messy but a lot more stable than water.
Have you tried coffee?
RE: Limb to use- Upper or Lower? - P.Rutherford - 03-23-2017
(03-22-2017, 11:18 PM)P.Rutherford Wrote:(03-22-2017, 09:33 PM)BigBill Wrote:(03-21-2017, 10:06 PM)CarlosPindle Wrote: BigBill,[quote pid='266' dateline='1490133976']
Have you tried placing it on the railing of your deck or directly over the deck's beam?
It's messier but have you tried using oil instead of water?
Carlos
No, it's just practice anyhow so the mess isn't justifiable. The rail is just as unsteady. That being said if I'm patient everything settles down eventually. I figure if I can get decent sights this way, it could be an analog to a boat, lol.
Diesel oil is messy but a lot more stable than water.
Have you tried coffee?
[/quote]
....and you can drink it afterwards.