Stena Line is adding a new deck to two of its vessels to try to meet future efficiency requirements.

The Swedish operator said it will send the ro-ros to China Merchants Jinling (Weihai) Shipyard next year to have an additional deck added.

The vessels are the 3,000-lane-metre Stena Forerunner (built 2003) and Stena Foreteller (built 2002).

The Stena Forerunner currently runs between the UK port of Harwich and Rotterdam in the Netherlands. The Stena Foreteller is on the Belfast-Liverpool route in the Irish Sea.

The company said the extra deck will increase capacity on each vessel by 30%.

“At Stena RoRo we see the investment of the installations on the Stena Forerunner and Stena Foreteller as a way to improve services for our fleet customers,” said managing director Per Westling.

“We strive to increase cargo capacity while also keeping sustainability in focus. It’s all part of Stena’s identity. Signing the contract with China Merchants Jinling Shipyard is a step in the right direction.”

The pair will also have shore power systems installed to comply with European Union regulations.

These are not the first performance enhancements on the two vessels. Last year, they switched to more efficient propellers and silicon hull coatings.

They also had interceptors added. Interceptors — hull protrusions that aid trim and manoeuvrability — are more commonly seen in high-speed craft.