[DG] [DG11] ais 700 only 13 miles range, it's normal ?

[Derek - Raymarine - Moderator]

Hi Antonio,

Was the previous AIS a class A or Class B, bear in mind Class A has a higher power for transmission and a more sensitive receiver too.

AIS operates in a similar way to vhf and so is generally line of sight between the Antenna for the purposes of range. How high is your antenna mounted?

If your antenna is mounted at a height of 40ft above sea level, a range of 60 to 70 miles would suggest the other vessel's antenna is mounted at a height of 1846.5ft above sea level - this calculation found here is the accepted means of calculating range between two vhf antenna.

I would suggest that the range you previously observed is based on an AIS signal being repeated by shore based transmitters repeating transmissions.

regards

Derek