Online alarm clock for 1:19 am
Before handing the Bluff wharf pickup to the next person on shift, set an alarm for 1:19 am so the changeover happens clearly and nobody assumes the other person is going. That leaves a useful checkpoint before 2:00 am for confirming who will meet the fishing vessel and where they will wait.
Your phone may settle into sleep well before the crew reaches Bluff, so check its power settings and keep the browser running after setting the time. The alarm depends on the browser remaining active; if it stops, the sound may never alert the person meant to meet the fishing vessel. Keep the phone powered, raise its media volume to a level you can hear, and test the sound once before leaving it beside you.
A 1:19 am alarm can carry through a quiet New Zealand house and wake people who have no part in the wharf handover. Keep the phone close to your side of the room, choose a clear but moderate volume, and close the door if someone sleeps nearby. Tell the replacement person that the alarm is set, too, so they recognise the sound and can silence it promptly once awake.