Name: Yachtsman
Rating: 4.1 (15 reviews)
Author: Strijar

Application for yachtsmen, kiters and windsurfers. 

It includes:

Countdown timer with sound and vibration alerts. 
Graph of ground speed measurement. 
Calculates the average values of the speed, heading, VMG and tack angle.
List of points, "go to" and route navigation
Audio-vibra message when the waypoint enters or leaves the tack sector.

Using main screen:

Change pages - "up" and "down".
Menu - long press "up".
MOB - long press "down"
VMG and Tack pages - long press "start" to change wind direction (by pressing "up" and "down")
Navigation page - press "Select" for context menu to add route
Timer screen:

Start and stop - press "start".
During countdown - press "down" or "up" to round timer to nearest minute.
When stopped - press "up" and "down" to change starting value.

Full manual https://forums.garmin.com/showthread.php?373524-App-Yachtsman