The North Sea is not the Med. Even at the height of Summer, bathers emerge from a swim blue and teeth-chattering. Nevertheless one may be often warmer in the sea at 10oC than exposed to a whipping wind and horizontal snow above the surface. At 10oC nevertheless you are only going to survive for 60 or 90 minutes before the remarkably high specific heat of water sucks the warmth from your very core and kills you.
I written before about a disaster in a RoRo - Roll-on, Roll-off - car ferry; the Herald of Free Enterprise that sank dramatically in 1987 while leaving Zeebrugge. The design flaw in RoRo ships is the free-surface of the car decks. Water weighs in at a tonne per cu.m., and even a small depth of water inside will weigh heavy if the surface area is large. A car ferry might be 150m long and 25m in the beam: so a cm of water on the deck - not enough to reach your shoe-uppers - could weigh 40 tonnes. Which is not so much if the deadweight tonnage [DWT=carrying capacity] is 7,000 tonnes. But, with no transverse or longitudinal bulkhead to compartmentalise the slopping water, this bulk will travel without impediment to the lowest side of the deck and increase any list to port or starboard. This may well allow the ingress of yet more water. It took less than 2 minutes to sink the Herald and 193 people lost their lives and everyone on board lost something material or psychological. If you're on the bridge in charge of one of these things, you want to be extra vigilant because a collision which holes the side is going to be bigger, wetter, problem than for normal ships.
Zeebrugge is a busy port and the tracks towards it criss-cross with tracks into other ports notably Ostend / Oostende and Anvers /Antwerpen / Antwerp. on 5th December 2012, the MV Baltic Ace, a vehicle shuttle, was taking a load of Mitsubishi cars from the port to Kotka in Finland. At 1615hrs hey dropped the pilot and headed North for the Skagerrak. As they picked up speed they noted a number of other vessels in the seaway, it was dark but ships have lights and the night was clear. Coming South heading for Antwerp was a container ship Corvus J and the two officers of the watch made radio contact with each other.
red port left in the bottle".
report by the Bahamas Maritime Authority. As the Corvus J blundered about in the dark she ran down one of the lifeboats but was able to pluck to safety the only passenger on board. The last survivor, the 4th engineer, was pulled from the sea after 2hrs immersion. Even with a survival suit that is at the outer limit of what is physiologically possible at 8-10oC.
The salvage was paid for by the insurers, authorised by the Dutch Rijkwaterstaat and carried out by Boskalis. They couldn't leave the hulk on the sea floor in such a busy shipping and fishing area of the North Sea. Not least, there were half a million litres of fuel oil on board. You really should check out the salvage video. Neat, efficient and a lot cleaner than, say, the British government which dumped thousands of tons of munitions into the North Sea after WWI, when people didn't know any better, and WWII when they did. Or as in Bari 1943 where The Man pretended to know nothing about the cargo on a sinking ship.