Limb to use- Upper or Lower?

[Fred_B]

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.

[LouisC]

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.

[EdCa]

Mostly I use the LL when on the hard. It's easier to reduce for me. Just a preference.

[Rdutton]

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

[BigBill]

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.

[EdCa]

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

[BigBill]

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

[quote pid='255' dateline='1489858376']
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]

[CarlosPindle]

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

[Guest]

Diesel oil is perfect and messy.

[BigBill]

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

[quote pid='266' dateline='1490133976']
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]

[P.Rutherford]

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

[quote pid='266' dateline='1490133976']
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?

[P.Rutherford]

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

[quote pid='266' dateline='1490133976']
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.