STAMFORD - A Stamford marina called for a full investigation today in the wake of a tugboat accident that caused the business an estimated $250,000 in damages. The accident happened last night at the Harbor House Marina when a tugboat pushing two barges crashed into the dock. Authorities say the barges were delivering sand to a nearby cement plant. Investigators are working to determine the cause of the crash. Given the force of the impact, boaters say it was extremely lucky that no one was hurt in the accident.