Irish Ferries do collect Advanced Passenger Information (API), as it is a legal requirement to collect this for the countries to which a passenger is travelling to. We collect most of the required API in advance of travel at the time of booking: Name, Date of birth, Gender (as per the travel documentation) and Citizenship.
The remaining outstanding information relates to Passport details (number, expiry), and this information is collected at the time of check-in when passports are scanned. There is no requirement at present for you to upload this information in advance of your sailing - just present the valid travel documentation/passports for the passengers booked at check-in at the port.
Further information on the API requirement and legal basis for the collection of API can be found in the relevant government websites as follows: