Here is a harbour item from the amazing 1st series of Triang Minic Ships, 1956-64. M857  sea sheet in good condition. It’s pretty good and over 60 years old.  Yes it is a lot like a shower curtain. This is 26 x 26inches  or just over 600mms square. The Varicella in the photo is just for scale/size.  Likewise the sunlight/shade.  I have another one too if it turns up.  Library photo.  Ref Sea3.