This type of Notifications alerts you when any of the selected vessels of yours is sailing closely to other vessels (or vice versa).
Vessel to Vessel Proximity: Get notified whenever other vessels are sailing close to a vessel you are monitoring. The distance is calculated by taking into account the actual dimensions of the vessels involved. Thus, when the distance between the two vessels is less than the length of the longer one multiplied by 3 and, in any case, not more than 1000m, these vessels are considered to be sailing in close proximity.
Note that you will receive this notification only if the distance between the two vessels remains within the above-mentioned limit for at least 4 minutes. This way, you will not be receiving multiple notifications for the same event.
This notification is inactive while the subject vessel is in a port or an anchorage.