John, to come back to your posting am I correct in assuming that you have a copy of Dönitz's memoirs (or access to them)? If he has used the word 'Hutments' that would be quite significant as the Ruhleben Barracks would never have been described as such. Could you take a moment to verify. (and any other mention of his accommodation). I should perhaps clarify something as I have been using the term Stadtheide. This is the modern name for the area but before demolition, when the Bundeswehr were using the barracks, they were known as Funf Seen Kaserne - Five Lakes Barracks and this could well have been how it was known in Dönitz's time.
I've memtioned of reminders around our school (Ruhleben) of its use for U-boat training. In the early days the remains of a Bachstelze Fa-330 observation autogiro were found. These were stowed in containers behind the conning tower of some boats and raised as a 'spotter'. There is info about them on the site here and I hope this link comes up :

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