Sailor for 30 years, last November, I was making my first transatlantic!! Fantastic and 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 SailFreeGPS App for smartphones or tablets that in addition to displaying COG, SOG, Compas, Position, 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).
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 6h)
I also added a MOB function (I would not have expected to go to water in the 4-5m swell during the transatlantic) and a night mode.
You can see your past track on a map (google map), add Waypoints and activate goto function.
You can save your track to GPX or KML file and share it
Share waypoint by SMS, E-Mail, ... and import it into SailFreeGPS from received message (by copying it into the clipboard)
Record your TRIP and Max speed.
You can activate a night mode
Bref, you can enjoy !!! and do not hesitate to provide me feedbacks or suggestions : firstname.lastname@example.org
Sorry for my bad english