Once had a cargo of HFO to deliver in the Baltic in Feb in the late 70s. Ice formed just as article said. Can remember the sea smoking as we met the first of the ice cakes. Later we were ramming the cracks ( this in a single skinned tanker!!) until it got so thick we had to wait for an icebreaker. You could see the plates flex in the ER as the broken floes ground past. All hands on deck to keep the steam on the cargo tanks to stop the HFO going solid, - happy days. Later we blacked out in Hamburg as the Ice mush blocked all the sea suction filters faster than the steam we were pouring into the sea suctions could melt it.
Troon marina water covered in very thin layer of ice this morning....Temp had gone to -10c in the central belt and -14c in the NW Highlands last night!!! I remember the sea in my home town of Lytham St.Annes freezing over in 1962!!
I lived on the Swedish coast for some years, so had considerable time to study the formation of sea ice !
Sea water freezes at lower temperatures according to salinity.
There are many things that influence the temperature.
As the sea only freezes on the surface, any currents will bring up warmer water to prevent freezing. This can be quite localised ........ some areas did not freeze whilst people drove cars on ice 30m away.
Some moorings have air bubblers on the seabed. The air rises to the surface with warmer water preventing ice formation.
And the sea ice may not always be saltwater ! The best ice is formed as follows :
Sea freezes with a rough surface,
A good fall of snow covers the ice.
Air temperatures go above 0C, then back below 0C (to about -27C sometimes)
You now have a mirror smooth layer of fresh water ice on the sea.
Other influences are depth and inflow of fresh water.
I was on tankers in the early 70's and spent a lot of time in the Baltic, summer and winter. What I remember was the bloddy noise down below as the ice scraped along the side of the hull. Whe we got in and discharged, the Mate had all the deck crew out ot the jetty with long handled rollers and red lead, as the hull was completely back to shiny metal where the ice had scraped it.
It was totally different in the summer, absolutely wonderful. I would love to go back there and cruise round in a yacht. Anybody going there and looking for crew?
How times change - Baltic coasting was one of my favourite summer trips, Loading in Hamburg, keil canal, old ships with B&W opposed pistons, all steam recip pumps and DC generators, cargo discharge rates varied according to how many nights ashore was wanted, long summer nights ashore.
The HFO comes from the Russian/Baltic state refineries now I presume?
You have reminded me of noise, the Indian crew hated it, Serang's mob on deck were frozen, Tindal and his gang did not like being down below. I can still visulize the reflection of the ships side plates painted surface moving under the pressure of the Ice outside.