Hello,
Sailor for 30 years, last November, I was making my first transatlantic!! How many memories...
But during these 15 days, I would have needed an app to see if the action of a trim (sheeting, easing, bending the mast, digging the sail, raising the tangon, ...) is positive or not.
So back, I created an Android Application: SailFreeGPS for smartphones or tablets that displays graphics with speed and course history. You can thus see if the new trims are positive or not (despite the waves, gusts or calms).
In addition I have created a page displaying COG, SOG, magnetic compass and current Position.
https://play.google.com/store/apps/details?id=com.frederic.sailfreegps
Moreover, since the values from the GPS are too fluctuating on our smartphones (while we advance to 6 kt stable, speed fluctuates from 4 to 8 Kt), I added a "filtering function" (average of a number of points that you can adjust).
You can also adjust how many past you want to see (from 30s to 20min)
I also added a Man OverBoard (MOB) function which will lead you to the MOB position using a graphical displaying.
SailFreeGPS also handle a night mode and allows you to share your position, Cog, SOG using one of the app installed on your device: SMS, e-mail, Facebook, WhatsApp, Snap, ….
Do not hesitate to provide me feedbacks or suggestions:
sailfreegps@gmail.com
Fred.