Ship broker Clarksons posted a decline in half year pre-tax profit, lifted revenue and underlined its confidence in future trading with an increase in its interim dividend.The shipping services firm said pre-tax profit fell to £9.0m for the half year to June 30th from £14.5m a year earlier. Pre-tax profits before exceptionals and acquisition costs was unchanged at £10.8m.Underlying earnings per share before exceptionals and acquisition costs rose to 41.8p from 39.2p. Revenues rose to £89.1m from £88.0m. Clarksons said it is increasing its interim dividend to 19p per share from 18p last time after a strong performance in challenging markets.Chief Executive Andi Case said: "In these difficult times we have remained focused on the key elements of our strategy by developing our full service client offering, taking advantage of opportunities to strengthen our core broking teams with new hires and enhancing both our research product portfolio and support infrastructure."He added: "The industry outlook remains challenging with the continued focus on the spot market limiting visibility. However, despite these headwinds we continue to make good progress and are trading in line with expectations. As previously highlighted we expect to see a slight weighting in performance to the second half of this year, reflecting the delivery profile of our newbuild activities."