OsmAnd, a map app for Android and iPhone, records tracks with its Trip Recording plugin and shares them as GPX, which Seamark reads directly. OsmAnd warns that iOS can pause apps in the background, which can interrupt a recording.
With the file in hand, open the leg in Seamark and choose Upload GPX track. Seamark drops the GPS glitches, works out the distance, times, speeds and night hours, and draws the track on the chart.
Menu and button names are quoted as the vendor's own documentation writes them, in English. Your app may show them in your language, and they can change between versions.
OsmAnd's own instructions, which these steps follow:
All GPX guides