heatherstreetsailing: Worksheet and Tables vs. StarPilot TI 89 Calculator

For the past few days I have been working with the StarPilot TI 89 Calculator and comparing process and results. The plan to work with the calculator was to keep working to find a quick and accurate way to process sights so that while on a boat under varying conditions I could develop an accurate fix in as brief a processing period possible - for the purpose of continuing to develop the toolkit towards an 'acoustic' and practical approach to Celestial Navigation.

I don't want to see myself spending 15 to 30 minutes determining a fix, while thumbing through multiple tables, making mistakes and getting sea sick while below.

All sights were taken with a Davis Mark 25 plastic sextant through an artificial horizon - under near perfect viewing conditions. All sights were taken at local time and adjusted for watch error. Each sight session consisted of 3 sights and averaged.

All worksheet sights were reduced via Pub 249 Vol 3 Tables.

From the following:

Course and Speed:    000d 0Kn (Stone Frigate)
Actual Position:            N43d43.0'   W079d24.0'
DR:                               N43d           W079d
Date:                             1 Feb 2016

Sight #1                        Sun UL
                                      UTC = 15:50:09
                                      Hs = 25d16.8'
Lon AP = 079d09.7'

Sight #2                        Sun LL
                                      UTC = 18:23:11
                                      Hs = 27d50.1'
                                      Lon AP = 079d24.9'

Sight #3    Sun LL
UTC = 20:10:15
                                      Hs = 19d00.1'

The results:                   Worksheet            StarPilot

Sight #1                         Zn = 153d T           Zn = 153.5d T
                                       Int = 39' A              Int = 42.3 A

Sight #2 Zn = 194d T Zn = 194.6d T
Int = 38' A Int = 34.2 A

Sight #3 Zn = 221d T Zn = 220.9d T
Int = 21' A Int = 16.6' A

Fix N 43d 38.0' N 43d 38.9'
W 079d 27.0' W 079d 24.9'

Accuracy within 7 nm within 5 nm

With StarPilot...
- DR is the AP
- a bit more accurate
- takes about 2 minutes versus 15 to 20 minutes to determine a fix
- keep spare batteries and sea water out - no solar power

Clearly the Starpilot approach is very accurate and very quick to produce a fix and I can't wait to do the real thing on the water.

Here are the Worksheets and the Plot...