(ShareCast News) - Shipping services company Clarkson posted a drop in first-half pre-tax profit as costs from the acquisition of RS Platou offset better revenues.Pre-tax profit for the six months ended 30 June came in at £10.8 from £14.1 in the first half of last year, as revenue jumped 30% to £145.3m. However, the rise in revenue was offset by a 29% increase in administrative charges to £115.4m, which reflected the additional costs from the acquired business.The acquisition of RS Platou completed in the first quarter and the company said it was "delighted" with the pace of integration, adding that cost synergies identified will amount to an annualised benefit of around £4m.On an underlying basis, which includes exceptional and acquisition-related costs, pre-tax profit was up 49% at £23.6m. The interim dividend was nudged up to 22p per share from 21p last year.Chief executive Andi Case said: "The multi-cyclical and volatile nature of our markets has once again been demonstrated by the sudden shift in oil and other commodity prices, giving rise to a consequential change in the demand supply balance in many markets."Across our broking and banking businesses, this backdrop has created both opportunities and challenges. The group made a solid start to the year, testament to the strength and breadth of our strategy and unique client offer.Case said that as previously outlined, the company's results will be weighted towards the second half."Whilst we are mindful of the ongoing headwinds in a number of our markets, our strategy has proven to be robust in this trading environment and with a strong balance sheet underpinning our business model we have confidence in Clarksons' prospects for continued progress in the second half."