Yes the similarities between my map and MoH's U-Boat map are uncanny, particularly due to the fact that like me, they actually researched the topic and found out what they looked like :biggrin: . I think with this theme its pretty hard to come up with something completely new as well as being completely realistic.
Thanks for the link Tracer, I also found that one during my researching. That pen at Cherbourg is the only one I could find evidence of that looked like that. Due to its curved nature it would be rather hard to make, at least when it comes to R's. Here are some links to pics/pages that I used as references:
http://www.usaaf.net/ww2/uboats/images/pages/subpens.htm
http://www.uboatwar.net/Fruboat-today.htm
http://www.uboat.net/flotillas/bases/la_rochelle.htm
I've also got some books here but no scanner.
Obviously I still have a lot of work to do on it. I've only built part of the basic structure with the lighting and a knock up crane to add a bit of detail and give an early impression of the finished product.