To summarize, an accident in a storm caused a barge to sink. The barge owner sued the tugboat owner for negligence. The tugboat owner lost because the judge ruled it was a trivial cost to buy and use a radio to monitor for bad weather. The judge stated that there was no general custom for tugboats to carry weather radios. However, the tug boat owner was nonetheless negligent for failing to carry a radio. The judge reasoned that the small cost of a radio, compared with its importance, made the tug boat owner negligent in failing to carry one.
This is VERY significant for cyber security: a firm could be considered negligent for a negative technology event if it could have been prevented with a relatively low cost and widely available control.