hello gentlemen! I recently acquired this via ebay for for only $4!(free shipping too) I asked the seller if there was any history and to which she replied:

I am preparing the blueprints to send to you. *I also have a picture of the USS Seadragon underway, a picture of a man named Franz standing on the deck of the Seadragon and the piece of the hull showing the shrapnel damage that my father kept all these years. *The hull piece is of course metal and about 5" x 5" big. *If you would like them, I would be happy to send them to you.
In another email, she said that her son still wanted to keep them.

Naturally, I had to ask if she sold the blue prints without her son knowing as I would ultimately not want to "break up a group". Have not gotten an answer yet...
I think it's nice that her son still had interest in his grandfather's keepsake and I would be glad to send them back to her for his sake!