Issues of trim and counter-trim

[Terje Langoy]

Hello, everybody…

I’m new to this forum but have been fascinated by the story of the Bismarck for some years now, which of course have resulted in some books and videos about the Bismarck and also the other ships of the Kriegsmarine. Well, I’ll just get on with my questions and take it from there…

A topic that interests me regarding a technical aspect of the Bismarck is the effects caused by and the counter measures executed after the bow-shot from the Prince of Wales. To this concern the subject is the effects caused by confined liquid surfaces. Although not an expert on the principles of trim, when a ship of her size suffers a 3° tilt by the head, I dare to say they have serious trim issues. My curiosity concerns the physical effect this had on her keel? For instance, how did they level her? And how did the damage affect her keel construction concerning aspects like yaw, roll & pitch?

My sincerest apologies if this topic already has been discussed.

As a minor digression, I have to emphasize that from my perspective the bow-shot was the one achievement that truly impressed me when I first got to know the story of the Bismarck. The Prince of Wales was unable to sink the Bismarck but she managed to send her back to port. That’s quite an achievement given the conditions she faced after the Hood blew up.

[José M. Rico]

After the two hits by POW, Bismarck was 3º down by the bow and had a 9º list to port. Because of this, the blades tips of the starboard propeller were out of the water at times! Therefore, to level the battleship and reduce the bow trim and list, the starboard void tanks in sections II and III were flooded.

[marcelo_malara]

Jose, how much water was let into those compartments? Was the ship trimmed by then? With what draught?

[José M. Rico]

I can't say. I guess that could be calculated on a model basin, but if the ship embarked 2,000 tons of sea water through the holes in the hull you can imagine.

[Terje Langoy]

First of all, thanks for the information. I noticed of course that these void tanks are in the vicinity of the impact area of the torpedo. Were the flooded tanks a contributing factor to the rudders being jammed, the blast causing a severe bulkhead displacement since the water had nowhere to exit?

[Terje Langoy]

I was wondering why I didn't get any response until I discovered my great blunder. Yes,
the torpedo struck the other side! It seemed so interesting to connect the void
tanks with the blast that I didn't give it too much thought before replying.

My sincerest apologies, folks...

Still, in an effort to resume the topic I started, I presume the torpedo made an entry hole
in the PORT side of the stern. With flooded void tanks and an entry hole, the stern
should, I guess, suffer a heavy weight on the section joints, right? If I were to say that
the blast from the torpedo shook the joint weldings but the weight from the internal seawater along
with the external sea conditions caused attrition upon them and helped the stern come all
the way off as she capsized, would that be probable at all?

By the way... This BAZAN avatar of yours wouldn't by any chance refer to the Spanish shipyard
that is currently building our beautiful Nansen-class frigates?

Regards

[José M. Rico]

I was wondering why I didn't get any response until I discovered my great blunder. Yes, the torpedo struck the other side! It seemed so interesting to connect the void tanks with the blast that I didn't give it too much thought before replying.

Actually you were right, the torpedo that disabled the rudders hit the stern on the starboard side. You asked if/how would the flooded tanks in that area have affected the rudders being jammed, well maybe others can give you a concise answer, I'm not an expert at all in damage control.

By the way... This BAZAN avatar of yours wouldn't by any chance refer to the Spanish shipyard that is currently building our beautiful Nansen-class frigates?

Yes, BAZAN refers to Ferrol's Shipyard. Now it is called NAVANTIA.
http://www.navantia.es/

[Terje Langoy]

I’ve always meant that if you’re not certain of having made a mistake, just commit a new one. It will at least verify whether you were wrong the first time. Well, I had a good laugh though!

Anyway, if someone knows more about the details surrounding the fascinating but missing section of the Bismarck, or where to find a more close-up-analysis on the causes of the fractured stern, it would be greatly appreciated.

Regards