first some words to my person: the brother of my grandmother died on UB81. Therefore I tried to find as much information as possible 7 years ago. So my knowledge is old. But I can share following informations:

in Eberhard Roessler, "Die Unterseeboote der Kaiserlichen Marine" is a drawing of the u-boat serie UB80 to UB87 with longitudinal section, deck plan, mechanism (I hope I found the correct words in the dictionary, the German words are: Laengsschnitt, Decksplan, Einrichtung). I wrote to Eberhard Roessler and ask him for the source of the drawing. He told me, that he found it in the Military Archiv of eastern Germany with the signature Ma 1443. It should be now at Militaerarchiv, Freiburg, Germany. I wrote to Freiburg, but they did not find it 7 years ago. Roessler wrote, that the original drawing was only a Little bit larger than in his book - and with poor quality.

I wrote to Krupp Company, the successor of the Vulcan Werft, but they do not have any documents of the u-boat dapartment of WWI.

A very interesting Website is www.ub88.org with many pictures. UB88 is not build the same time than UB81, but I think, it was similar.

Diving and shipwrecks: do you know Ron Young & Pamela Armstrong "Silent Warriors - Submarine Wrecks of the UK, Volume 2" There is a chapter about UB81.

On YouTube there is a Video of diving UB81: [www.youtube.com]

If you Need more info (war diary, interrogation of the survivers) drop me a message.

Regards
Thomas

regards

Thomas