Rail & Sail Irish Ferries Swift Sailings
 

Irish ferries Rail 'n' Sail Swift sailings are now attracting a £/€4 premium.

Stena don't seem to replicated this with their fastcraft, so if you're travelling out of Dublin at lunchtime, or from Holyhead at 10am, then going with Stena is about 10% cheaper; at all other times, IF have a monopoly with their better fastcraft frequency.

Updated Irish Ferries SailRail section
 

Irish Ferries have recently updated their SailRail section and it now includes an alphabetical list of all British stations by zone from Dublin Ferryport.
It also includes a comprehensive timetable for the Route 53B bus; Heuston/Busáras - Ferryport.
The current brochure should by now be available in the leaflet rack at many railway stations (the 2009 issue was stocked at Heuston, Connolly and other stations).
http://www.irishferries.com/fares-of...ares-sail&rail

In my opinion, this route should not be called the 53B bus as this suggests it is a service bus provided by Dublin Bus and should therefore accept all passes and standard bus fares should apply. However, having the used the service, no passes are accepted and a fixed fare of €2.50 applies. The bus driver told me that Irish Ferries contract the service from Dublin Bus.

To avoid confusion with it being a regular service:
it should not have a route number and it should not be operated by Dublin Bus.
Dublin Bus operates standard services and fast services to the airport and all accept passes. The same logic should apply to port services.
StenaLine offers a free service to Dublin port from a private company.