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A Simple to Use, Marine Navigation Calculator App - for Sailors and Navigators learning to use Charts.

The TVMDC App performs three functions: -
* Instant TVMDC corrections between True, Magnetic and Compass bearings.
* Set & Drift Calculations from two known Fixes.
* Calculation of "Course to Steer" (CTS) based upon a Destination while factoring in both TVMDC and 'Set & Drift' corrections.

Allows you to move between True, Magnetic and Compass bearings instantly. A True, Variation, Magnetic, Deviation, Compass (TVMDC) Calculator.

Ideal for Sailors who are learning to Navigate with Charts.

Includes corrections for : Variation, Annual Magnetic Variation Drift, a boat's Deviation, Set and Drift factors.

Simple to use: Input values form the your nearest Chart's Compass Rose: including Variation and Annual Increase. Along with your boat Compass's Deviation.

The Calculator will instantly correct between any: True, Magnetic and Compass bearings.

Add two known fixes along with your boat's Heading and Speed through the Water. Press Calculate and the App will display your calculated "Set and Drift" values along with a graphical sailing triangle.

Any heading or bearing is adjusted for Magnetic Variation and Deviation.

Add your Destination and the Calculator will provide your best Course to Steer: factoring in TVMDC and Set and Drift errors.

American Sailing Association (ASA) course 105 (Navigation) is an ideal back ground for the App.

Also, wikipedia's TVMDC description : http://en.wikipedia.org/wiki/TVMDC

YouTube TVMDC App Introduction tutorial: https://www.youtube.com/watch?v=u4d5wCgPxwg

Extensive Help at: http://www.arintoapps.com

Runs on iPhones 5, 6 and 6+, 7, 7+ in Portrait mode ONLY.

Planning on new versions and extensions; so please feedback feature requests?

What’s New

Version 4.0

This app has been updated by Apple to use the latest Apple signing certificate.

Improved usability with new dynamic color of Calculate button to help user understand when inputs have changed or not.
Improved textfield inputs now do not require user to hit return to input values.
Updated for iOS 10.x
Minor bug fixes.

Ratings and Reviews

3.0 out of 5
2 Ratings

2 Ratings

Jlblan2 ,

Great training app for boaters and cruisers

This app is exceptional tool for honing your boating skills while not on the water (like those cold winters up north). Safe boating and piloting courses can really take advantage of this app.

Alireza Saraei ,


Many tanx for your good program.
As a marine officer inform you, mostly we need a program for gyro error. Final calculate DEVIATION. If mention this part your program will be tje best.

App Privacy

The developer, peter hopper, has not provided details about its privacy practices and handling of data to Apple.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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