Hi David,
Thanks for the picture, yes they are rather odd looking. Apparently they were a bit wet and didn't go to sea if the weather was poor. Two were lost, one to a collision with another vessel and it came off worse and the other was mined. So I have heard the rationale was a very low profile and to ram any sub on the surface. Later in the war they carried depth charges.
Very good picture with plenty of detail thank you very much a welcome addition to my file when I start building one later this year.
Daryl