That looks like either a practice bomb or a float from a naval mine sweeper. Any idea of rough height?...to confuse the issue I even think that the Navy used practice bombs as floats.....
Here is a link to a rough guide
It's about 6' and has a detachable tail section. Looks also like it can thread a fuse in the nose tip, maybe 1 1/4 threads. I have looked at a lot of bombs on the net and it seems there is a pattern as to what type of tail fins they have. It seems the Germans used solid and the Americans used a open box fin assembly. I'm not sure if that holds water or not but it did appear to be true. The only person that has offered info was an older man who walked into my business and looked at it for several minutes. When I walked over to him he said "I must have dropped a thousand of those damn things." After talking several minutes to him I learned he was a P51 pilot in WW2. He never went in to details but he did say that he flew several combat missions during the war. This was about 20 years ago. Anyway thanks, and if there is any more info please let me know.