I just went to the home page of SEAiq that I use on the iPad and they had this announcement:
Important: ActiveCaptain
We are informed on May 23, 2018 Garmin will be make incompatible changes to the ActiveCaptain server. After this date, the current ActiveCaptain data will continue to work in SEAiq. However, no further updates will be available for download. We recommend users sync offline data on their devices before the May 23 cut-off. We are considering updating SEAiq support for ActiveCaptain but do not have definite plans yet.
Bummer for SEAiq users unless they update support for the "new" AC.