I've been thinking about my father a lot in the last tuthree days. Yesterday, Wikipedia's On This Day reported the anniversary of the Battle of Barossa (1811) an Anglo-Portuguese victory against a much larger force of French infantry in the Peninsula War. Since I was a boy, I've had a boy-like interest in the Napoleonic Wars possibly because of a namesake. Barossa rang a bell because it was one of the (successful) British battles that named a class of Royal Naval destroyers including Corunna, Agincourt and Alamein. Just after I was born, my father was appointed to HMS Barossa (D68), so the ship was for a while a fourth child in our family. His loyalty to his commands was almost absolute. In the school where my brother and I started our very expensive education, the boys (all boys natch) were assigned to a colour-coded 'house' named after a Hampshire river. The Brother in Beaulieu, self to Hamble. This was only really important at the annual summer sports day when small boys in white shorts were pitted against each other to amuse the parents. My father refused to support either of his sons' teams but rooted instead for Meon because HMS Meon was his current home-from-home. And yes, there is a coxennion with the Australian Barrosa Valley and its wine.
Today is the anniversary (1987) of the Zeebrugge disaster; not to be confused with the Zeebrugge raid (1918). The disaster reveals some interesting science as well as being a rather good example of a "for want of a shoe, the horse was lost" normal accident. MS Herald of Free Enterprise was designed to be a hyper-efficient RORO ferry serving the English Channel. We nowadays think that roll-on-roll-off ferries are the only conceivable way to transport cars across water. But I can remember my father driving up the quay in Fishguard until each wheel of the family car was settled in two enormously strong coir hammocks. The jalopy was then swung up into the air by a quayside crane and deposited on the deck of the Rosslare ferry. Clearly this method of loading becomes impossible if more than a handful of people had cars to bring with them on holiday. That might have been as late as the annual Irish family holiday 1961. Shortly after that RORO ferries became the standard.
The Herald was designed to work more efficiently than the competition. Efficiency could be passed on to passengers as competitive prices and Townsend-Thoresen, the owners, could sell more tickets. The ship was designed for Calais rather than Zeebrugge so she didn't really fit the loading ramps of the port, accordingly, on arrival in Belgium the forward ballast tanks were flooded so that the ship kneeled into the dock. The cars were herded on as quickly as possible - turn-around time is where efficiencies can be achieved as we all know from Ryanair. It was the habit of the crew to leave the bow doors open as the ship started off across the harbour to clear out the exhaust fumes of the busy loading process. The doors were to be closed before the ship went out past the breakwater into the open sea. The man responsible for closing the door was having a snooze in his cabin, the officer responsible for ensuring the door was closed made an assumption that the snoozer was doing his job, another senior crew member didn't act because it wasn't his job, the Captain couldn't see the doors so assumed they were closed and there was no warning light on the bridge designed to tell him otherwise. Oh, and they all forgot to adjust the trim so that the RORO ramp was back up to the requisite 1.5m above the water level. So the ship left the safety of the harbour exposed to the rough North Sea.
Four minutes later a wave slopped in through the doors and sloshed about the enormous free surface (20m x 120m) of the car desk. 10cm of water across that area is 240 tons which was probably less than the weight of the vehicles but they were stationary (and positioned to even up the ship's trim) while the water was moving with the least change in the heel of the ship. A slight list to port was pushed further by the tons of water which brought the left corner of the loading door nearer to the sea, more water rushed in and 90 seconds later the whole ship turned on its side and sank; providentially onto a sandbar so there were some survivors even though the water temperature was 3oC. 193 people died. Many people behaved in a heroic manner: one man made himself a human bridge between two sections of a stairway and allowed people (complete strangers) to scramble over him to safety. Various ships in the vicinity put themselves at grave risk to pick off survivors before they froze and drowned. As the tide rose in the dark, the rescue workers reluctantly stopped work; when they returned at first light everyone on the ship was definitely dead from hypothermia and exposure. In the SS Estonia, a more dramatic RORO disaster in the Baltic in 1994, the survivors were much more skewed as to their age, sex and fitness profile.
The free surface effect is most exaggerated when water, which is heavy and the opposite of viscous, is involved but the shift in the centre of gravity which is the core of the problem can occur with any unsecured load especially in containers only partly full: fuel-oil, coal, wheat, fish on trawler decks. In the days of sail, storm damage might break internal bulkheads to cause the load to shift and the crew were put to back-breaking labor in atrocious conditions to shift cargo and restabilise it. That's when they earned their tot and lobscouse.
My father, a sea-captain himself, was quite uncompromising in his assessment of the responsibilities of the officers and particularly the Captain of the Herald. In his book, the buck stopped with the Captain, it being his job to make sure that systems are in place that prevent accidents happening and if something goes wrong that there are plans in place to minimise the damage. You can't blame your officers, let alone the men at the work-face; you can't look to your owners let alone the share-holders. "It would have been better for Captain Lewry if he had gone down with the ship" was The Da's assessment from behind the Daily Telegraph as he read reports the following day.