Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-02-2013, 10:33   #46
Registered User

Join Date: Nov 2007
Location: Probably in an anchorage or a boatyard..
Boat: Ebbtide 33' steel cutter
Posts: 3,538
Re: Self Taught Celestial

A quick go on Opencpn came up with this... look about right from the numbers?


Click image for larger version

Name:	Capture.JPG
Views:	82
Size:	123.4 KB
ID:	55712
__________________

__________________
conachair is offline   Reply With Quote
Old 25-02-2013, 11:29   #47
cruiser

Join Date: Jan 2013
Posts: 72
Re: Self Taught Celestial

Quote:
Originally Posted by PCFithian View Post
Scimitar, I greatly appreciate your work on this. However, I 'm not sure I understand your progression with the the corrections and determinations from there.

Can you explain a bit further?

__________________

__________________
scimitar is offline   Reply With Quote
Old 25-02-2013, 12:37   #48
Registered User

Join Date: Feb 2013
Location: Long Beach, IN
Posts: 16
Re: Self Taught Celestial

OK, now I understand the corrections that were made in Scimitar's workup. But they should not be necessary, right, since:

1) The sextant was adjusted so that the index errorr was zero at the time of sight

2) There should be no dip correction, since I was using an artificial horizon

3) There should be no altitude correction for semi-diameter, since the sextant image and the artificial horizon image were merged together.

Am I missing something here?

I'm still trying to figure out how to get the Hc from the Kolbe's Long Term Almanac.

Conachair, the LOP near the bottom of Lake Michigan is exactly where I am. The other one is off a bit, but since these were the first two sextant readings I've ever taken, maybe not so bad.

I think I'm going to order one of the Davis Artificial Horizons to prevent wind effects on the surface of the water pan and get more practice at this.
__________________
PCFithian is offline   Reply With Quote
Old 25-02-2013, 13:09   #49
cruiser

Join Date: Jan 2013
Posts: 72
Re: Self Taught Celestial

Quote:
Originally Posted by PCFithian View Post
OK, now I understand the corrections that were made in Scimitar's workup. But they should not be necessary, right, since:

1) The sextant was adjusted so that the index errorr was zero at the time of sight

2) There should be no dip correction, since I was using an artificial horizon

3) There should be no altitude correction for semi-diameter, since the sextant image and the artificial horizon image were merged together.

Am I missing something here?

I'm still trying to figure out how to get the Hc from the Kolbe's Long Term Almanac.

Conachair, the LOP near the bottom of Lake Michigan is exactly where I am. The other one is off a bit, but since these were the first two sextant readings I've ever taken, maybe not so bad.

I think I'm going to order one of the Davis Artificial Horizons to prevent wind effects on the surface of the water pan and get more practice at this.
I added index error from my sextant and dip is when I stand on deck of my boat ( 2.80m)



http://www.starpath.com/resources2/LTA_Instructions.pdf

Can you take Moon or Jupiter sight this evening and post sextant reading and time, I will do that as well, or star, let say Polaris. It is easy to find.


And why you are using it, download nautical almanac i correction tables from here

http://navsoft.com/downloads.html

download sight reduction tables from here

http://tinyurl.com/avqqnu9

You can print it if you like, I printed it and even made my own sight reduction tables. It cost me 5 in the ink
__________________
scimitar is offline   Reply With Quote
Old 25-02-2013, 14:00   #50
Registered User
 
SVTatia's Avatar

Join Date: Jul 2007
Location: Toronto, Canada
Boat: Luders 33 - hull 23
Posts: 817
Re: Self Taught Celestial

Quote:
Originally Posted by Celestialsailor View Post
...on second thought...maybe your GPS is not working all that well...You're an aircraft enthusiast that has navigated into a sailing forum.
+1 on that.

It seems fliers never understand the needs of a sailor because their lives depend on an engine being on 100% of the time.
__________________
SVTatia is online now   Reply With Quote
Old 25-02-2013, 15:23   #51
LJH
Registered User

Join Date: Mar 2012
Location: Nova Scotia
Boat: Wauquiez Centurion 42
Posts: 274
Re: Self Taught Celestial

Quote:
Originally Posted by SVTatia View Post
+1 on that.

It seems fliers never understand the needs of a sailor because their lives depend on an engine being on 100% of the time.
Perhaps you haven't tried gliding!
__________________
LJH is offline   Reply With Quote
Old 25-02-2013, 20:08   #52
Registered User
 
Celestialsailor's Avatar

Join Date: Nov 2006
Location: In Mexico, working on the boat
Boat: Hallberg Rassy 35. and 14ft.Whitehall pulling skiff.
Posts: 8,013
Images: 5
Re: Self Taught Celestial

Quote:
Originally Posted by goboatingnow View Post
It took the combined efforts of the NSA, the Israelis and Siemens ( the makers of teh PLC in question) to load a 'virius' into it to shake the centrifuges to bits in Iran, in that they delayed them for about 40 days.

If someone loads a virus into a GPS satellite, firstly a large number of people are going to get fired in a certain underground bunker. and secondly since each satellite is independent they would have to affect all of them ( and then what about GLONASS).

Seriously a bus will drop on you head first, yet I dont see you building battle armour to handle that!!!..

Dave
I think I'll take Dave M's approach of " Wise sailors learn celestial for the same reason parachutists carry a reserve chute and for the same reason we have life rafts",
Than your bus analogy. One is based on fact, the other a hair brained speculation.
__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow - what a ride!"

http://wwwjolielle.blogspot.com/
Celestialsailor is offline   Reply With Quote
Old 26-02-2013, 01:41   #53
Registered User
 
GrowleyMonster's Avatar

Join Date: Dec 2012
Location: New Orleans
Boat: 1976 Cal 2-27
Posts: 1,298
Re: Self Taught Celestial

You shiuld always check the index error and apply it. Many old school navigators set the index a minute off or on, to ensure that they did apply it and rhat it was applied in the right direction. If you check it for a round of sights and it is zero, add zero just to make it part of your routine to consider index error.
__________________
GrowleyMonster
1976 Cal 2-27, MR WIGGLES
Now with clean, dependable electric propulsion!
GrowleyMonster is offline   Reply With Quote
Old 26-02-2013, 14:18   #54
Registered User

Join Date: Feb 2013
Location: Long Beach, IN
Posts: 16
Re: Self Taught Celestial

I found a good training tool for checking manual sight reductions, Sight Calc app for iPhone
Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	68
Size:	94.9 KB
ID:	55784  
__________________
PCFithian is offline   Reply With Quote
Old 26-02-2013, 16:14   #55
cruiser

Join Date: Jan 2013
Posts: 72
Re: Self Taught Celestial

Quote:
Originally Posted by PCFithian View Post
I found a good training tool for checking manual sight reductions, Sight Calc app for iPhone

check this then...








__________________
scimitar is offline   Reply With Quote
Old 27-02-2013, 04:56   #56
Registered User

Join Date: Feb 2013
Location: Long Beach, IN
Posts: 16
Re: Self Taught Celestial

Scimitar, the Sight Calc app on the iPhone yielded essentially the same results as yours.

I've got this pretty much figured out, now I am waiting on the artificial horizon to arrive and the clouds to go away. Good thing my DR position is not changing at this point!

In my opinion, Rodger Farley's treatise is the best resource to get started on this, posted here again for reference: Celestial Navigation
__________________
PCFithian is offline   Reply With Quote
Old 05-03-2013, 10:43   #57
Registered User

Join Date: Feb 2013
Location: Long Beach, IN
Posts: 16
Re: Self Taught Celestial

I was finally able to take some sights over the weekend, reduce to find Hc and Zn, and plot. I was within ~2 miles of my exact position for 3 sights, good enough for me on my first try. See attached plot sheet.

Another good reference for those learning celestial navigation is the USNO Celestial Navigation Data for Assumed Position and Time, which can confirm the results you develop:

Celestial Navigation Data for Assumed Position and Time

After additional practice with the sextant, including star sightings, I'll try to figure out the sight reduction using the Kolbe Long Term Almanac tables instead of the iPhone Sight Calc app.
Attached Thumbnails
Click image for larger version

Name:	Position Plot 4 March 2013.jpg
Views:	68
Size:	228.2 KB
ID:	56249  
__________________
PCFithian is offline   Reply With Quote
Old 07-03-2013, 05:10   #58
Registered User

Join Date: Feb 2013
Location: Long Beach, IN
Posts: 16
Re: Self Taught Celestial

Here's a sight form I worked out for using the Kolbe LTA and the iPhone app Sight Calc
Attached Files
File Type: pdf LTA Sight Workform.pdf (173.8 KB, 36 views)
__________________

__________________
PCFithian is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:45.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.