Defence and engineering consultant Cohort's shares fell sharply after it said pre-tax profits for the full year will miss previous expectations.The company pointed to a poor performance at SEA, its surveillance systems and software company."SEA's performance has been poor and action is being taken to redress this," chairman Nick Priest said."As this will take some months, the board now expects that the group's trading profit before exceptional costs for the full year will be below previous expectations, though will still show an improvement on the 2009/10 result."Cohort posted a pre-tax profit of £721,000 for the six months to October 31, down from £2.42m over the same period the previous year. Revenues fell to £32.7m from £38.5m.