Sight Calc app for iPhone and iPad
Developer: Nuvocom Incorporated
First release : 31 Jan 2012
App size: 6.99 Mb
Sight Calc is a specialized calculator for the that eases the task of calculating sight reductions via the "Law of Cosines" method. It does not use Nautical Almanac data, so you must first compute LHA (Local Hour Angle) and declination, and determine your approximate latitude. It is designed particularly for students learning celestial navigation, such as the Off-Shore Navigation courses taught by the US Power Squadrons®. If you are unfamiliar with how to do sight reductions, some good resources are available from the U.S. Power Squadrons® at www.usps.org. In particular, this calculator is useful in conjunction with Form SR96a, www.usps.org/eddept/n/files/sr96a.pdf
Inputs are always entered as two numbers:
Degrees - left display
Minutes - right display
If you already know the value in decimal degrees (e.g., 44.48833), key it in followed by ENTER, then press ENTER again to indicate zero minutes.
Sight Calc will prompt you to enter six number in sequence:
LHA (degrees)
LHA (minutes)
Lat (degrees)
Lat (minutes)
Dec (degrees)
Dec (minutes)
After you enter each value, it will be displayed in decimal degrees in the corresponding register. After you enter the last value (Dec minutes), Hc and Z will be computed and displayed.
**NEW in version 1.3: enter North Latitude as a positive number, and South Latitude as a NEGATIVE number. Sight Calc will take the absolute value of Latitude in the law of cosines formula, but needs the hemisphere to calculate Zn. The sign of Declination is positive if Latitude and Declination are the same sense (both North or both South). If they are different, key the minus sign before the first declination digit.
If you want to do repeated calculations with some of the same numbers, just enter the changed numbers and press ENTER to accept the remembered values from the previous sight reduction. To start over fresh at any time, press "C" to clear everything.
CE clears just the Current Entry.
Please report any bugs or suggestions to:
[email protected]
Latest reviews of Sight Calc app for iPhone and iPad
I love this App! It looks like it has been out for a while and had a lot of good reviews. Im only putting this as a 2-star review at this time to bring attention to the fact that using this App when you are lost at sea may get you lost even further! From my testing the result Hc and Z is spot on! But will the sailors using an app like this know the difference between Z and Zn? If you assume that the result Z value is your azimuth and graph your sight based on that value, you are going to be lost at sea. Another correction is required to determine the azimuth. You have all of the inputs to make this correction, why not provide the azimuth output? As documented in the Ho229 tables: Latitude SAME Name As Declination - N. Lat, LHA < 180 .... Zn (azimuth) = 360-Z Latitude CONTRARY Name to Declination - S. Lat, LHA < 180 .... Zn (azimuth) = 180+Z The app is very easy to use and does the basic calculations correctly. Please calculate and output the azimuth and I will gladly update this to a 5 star review!
This is a great App for doing sight reductions using the law of cosines. I would give it a five star rating except it has compatibility issues with iOS 10.
Easy to use. Calculations are accurate. Ive been using it for a month doing Sight Reductions.
User friendly and accurate. Saves a lot of time
A real timesaver when reducing sights using the USPS forms. Eliminates the need to find and program a scientific calculator. Well done!