Vesper Marine transponders are designed for highest accuracy. The dimensions of the vessel, the vessel position data (GPS) and continuous heading are used to determine potential risk and trigger anchor watch alarms.


The calibration data provides the transponder with vital information about the position of the bow, stern, port and starboard of the vessel with reference to the GPS position. Powered by 5Hz, 50 channel GPS, the vessel position is updated 5 times every second.


An important consideration is how your smartAIS uniquely takes advantage of heading data. At anchor, heading allows your smartAIS to determine the precise position of the bow from the anchor.


To understand how it works, here's an illustration of a boat with the GPS antenna at the stern.




Without heading





With heading




Bread crumbs - a good indicator of anchor position

A useful feature of smartAIS transponders is Breadcrumbs. Breadcrumbs draw a pattern of the boat's position which over time can be a good indicator of the anchor's position and whether it is dragging.

Anchor Move is designed to fine-tune the anchor position in case you have not marked it at the time of dropping anchor. In the absence of heading, it can also be used to move the position A (marked anchor position) closer to X (actual anchor position) by the distance of the GPS antenna position to the bow. But since subsequent positions will still be calculated based on the GPS antenna location you will need to increase the size of the circle by this distance.


To ensure the accuracy of Anchor Watch alarms, follow these steps:

  • Mark the anchor position at the time you drop the anchor.
  • If you have a heading sensor, keep your heading sensor ON.