I've heard mention that a U-boat actually could outrun a DD in rough seas.

The reason is, a sub cuts directly through the waves due to its hull design, whereas a DD has to ride pretty much over the crests and down through the troughs. That slows a ship down.

I´ve heard that too. :up:

I just did finish a Book about the Scharnhorst, and in there they stated a few times that in rough See they had to slow down because the DD's did take to much damage by the See, so that is a clear indication that the DD's and also the BB's had the problems with the High See. It's not that they would not be able to run on higher Speed but that the Damage they took on the Gun Turrets and on the super Structure would inable them to engage in a Battle. There are some passages where they did write that they realy had to drop the speed to as low as 10 Knots. So if a DD can't catch you in high Sees i think that's realistic as a Sub has better chances to keep speed below the Weaves and a chasing DD would risk to Damage it self by the Hunt.

I can't remember if it was Iron Coffins or one of my other books, but they outran a Destroyer in heavy seas. The author gave the explanation that the Destroyer rode up and down the waves, whereas the U-Boat sliced right through them. Just as you said.

As for firing in heavy seas, there's the segment in Iron Coffins when their boat surfaced in a raging hurricane - right in the middle of a convoy. The seas were so bad that neither side could fire. They dived and rode the storm out while feeling sorry for the poor sods in the convoy.

Also, in one of his patrol reports Endrass in U-46 said;

"June 6th 1941. Weather deteriorating. Storm force 9 to 11. Powerful seas engulf the boat. A tanker comes in sight. Even under the prevailing conditions an attack at short range may be successful. Decide to go for it. It is difficult to keep the boat at periscope depth."

He fired then couldn't see a thing through the periscope due to the heavy swell. When he did finally get a glimpse it was to see the ship coming straight for him. They got rammed but it only knocked out the persicopes and jammed the bridge hatch.

The fact that he said "Decide to go for it" shows that shooting in heavy seas was a bit of a lottery.