Clipper Group's Irish Sea freight specialist Seatruck Ferries has posted a more than 10% rise in cargo volumes for 2017.
Overall market growth was 3.9%, it said, citing figures from IRN Freightstat.
It said volumes on its three routes have grown more than 30% since 2015.
"Their long-sea unaccompanied service has significantly grown in popularity and 2017 was another strong year," it added.
Seatruck has committed additional tonnage and increased sailing frequency in line with customer demands, it said.
The company operates 76 departures per week between Heysham-Warrenpoint, Heysham-Dublin and Liverpool-Dublin.
The strongest growth has been into Dublin where Seatruck operates five daily departures in the busy midweek period.
"We believe that the continued and worsening HGV driver shortage in Ireland and the UK is leading to a growth in unaccompanied trailer shipments, as operators seek to use this vital resource more efficiently," it said.
"By shipping trailer only, from ports which reduce road mileage compared with the traditional transit through Wales or Scotland, operators can make significant savings in an increasingly competitive logistics landscape."
