Reminds me of an event here in Sweden when a military patrol boat accidentially crashed into a car ferry after the two captains could not agree about who had the right of way. The ferry lost some paint while the patrol boat sustained significant damage and was put out of action.<p>Military boats look strong and are built to be fairly fast and withstand enemy fire, but pure mass is still far more important in a collision. Commercial passenger liners also seem to be quite over-engineered to withstand a lot of punishment, maybe as a result of those being the boats that can continue to operate decade after decade.