977 U-boat

[Sensekhmet]

Originally Posted by bobchase

For them, their ship really is moving hard in those seas but let a DD or DE come alongside for refueling. If they pay attention, what constitutes rock & roll gets seriously re-written when you watch the smaller ship half-buried in seas that cause a carrier's deck to only pitch or roll +/- 5 degrees.

A little DE does move about in almost any sea so one would presume that a surfaced U-Boat would behave much like that. However, there is a sea-state where the swells (waves) are very sharp, almost vertical, and far enough apart where a DE's hull won't rise to meet the swell. The water just simply breaks onto the foredeck and rolls off at the forward the breakwater. Down below you'd think that you were in much calmer seas if it wasn't for the big 'shudder' that goes though the ship every time a wave breaks. On a U-Boat, in that sea state, one would imagine that the sea would simply roll over the whole sub and never even break.

Bob

Speaking of destroyers in bad weather, I've read an account of a Polish destroyer in WW2 in the midst of a monstrous storm. The whole DD group proceeded at top speed with wind from the stern and they all suffered from a peculiar phenomenon. The ships would loose their course, and start to turn by themselves. They would also list badly and it continued until they were at 90 degrees to the wind. At that point the ship would slowly straighten itself and be ready for another uncontrolled turn... the situation was absurd and it made it impossible for the group to stay in any kind of formation.

[Sailor Steve]

I missed this part the first time around:

The range was 400 yards; we could get no closer, for
300 yards was the danger limit. If we had gone much
nearer, with all the explosive we had on board we should
have been in danger from the shock-wave of our own
torpedo. Many U-boats were in fact lost this way.

How would he, or anyone, know that?

[Schroeder]

Maybe survivors told the story.

[bobchase]

Originally Posted by Sensekhmet

Speaking of destroyers in bad weather, I've read an account of a Polish destroyer in WW2 in the midst of a monstrous storm. The whole DD group proceeded at top speed with wind from the stern and they all suffered from a peculiar phenomenon. The ships would loose their course, and start to turn by themselves. They would also list badly and it continued until they were at 90 degrees to the wind. At that point the ship would slowly straighten itself and be ready for another uncontrolled turn... the situation was absurd and it made it impossible for the group to stay in any kind of formation.

That is a hard one to understand. The only thing that comes to mind is that a ship has to make way through the water to have steerageway. If the current goes faster than the boat, then the boat has negative forward speed and starts handing as if it is in reverse. (Right rudder becomes Left Rudder) I've done this in a sailboat on a strong outbound tide. On a destroyer capable of 30+ knots? I can't imagine that kind of current speed unless you just roared past Three Sisters Island heading for the down hill side of Niagara Falls.

Bob

[Sensekhmet]

bobchase, I found more info.The event took place in heavy seas in the last night of the Bismarck chase, 26th/27th of may. The destroyer group was the 4th flotilla of commodore (?) Phillip Vian, consisting of: HMS Cossack, HMS Maori, HMS Sikh, HMS Zulu and ORP Piorun. Piorun was an N class destroyer but according to the account, all ships suffered from the same phenomenon.
Here is what Piorun's commander had to say (my translation):
When we have reached the ordered speed of 26 knots all five destroyers lost all manouverability, which was by the way forseen by admirality's 'ships' manouverability description' (?). With strong wave from the stern and speeds above 25 knots the ship went totally out of control. With the stern rising high and the bow ploughing deep in the water, the ship listed to either side, until the list of 60 degrees (!) and in this position it turned either way taking in water through superstructures and ventilation. When the stern was pushed around by the waves 120-150 degrees off course and the ship was bow to the waves again, the ship slowly righted itself and begun to respond again to rudder and engines. It's worth noting that at that moment, Piorun had less than 40% of fuel on board, and although in theory it was a ship that was immune to capsizing, trying to navigate in horizontal position and being completely helpless must be considered a difficult experiment indeed.
Taken from Jerzy Pertek's 'Wielkie dni malej floty' (Small fleet's great days), 1972 edition (on a side note I'm surprised you could buy a book like this in Poland at the time...).