Marine services company James Fisher is pushing further into the fields of submarine rescue and offshore wind turbines after increasing profits by more than a quarter in the first half of year.

The FTSE 250 business has been building up its presence in the renewables market, repairing blades on wind turbines and monitoring cables. Earlier this year, the company signed its maiden long-term maintenance contract for the largest wind farm in the world in the Thames Estuary.

“We are miles ahead of Denmark or Norway in offshore wind,” said chief executive Nick Henry. “There are more and more wind farms being built in the UK and the industry is maturing fast, while the cost of installing these farms comes down quickly.”

Mr Henry hopes the five-year contract with the Thames Estuary will be the first of many long-term maintenance contracts.

James Fisher is also looking further afield at Taiwan, China and the US as potential markets that are starting to invest in offshore wind, although Mr Henry added “we have enough in the UK to fill our tummies at the moment”.

The company's submarine rescue business is growing well too, thanks in part to rising defence budgets in developing countries. In March, the first of two submarine rescue systems was delivered to the Indian Navy, with the second due for completion before the end of the financial year.