Looks almost as bad as some of the low-budget Star Trek (TOS) monster props.
That was what was so great about those old movies. Someone actually had to use his hands to build something tangible. It shows, even if cheap, as something real. Now we have endless flat lifeless CGI.
If I remember correct, in the movie it was part of a small submarine operated by midgets. German agents were trying to steal the designs for the sub. Make people think there was a serpent in the Loch, not a sub.