as useful as a fly screen on a submarine

This saying was conceived by Bob and his buddy Mel while on a cycle ride to Portsmouth Dock Yard via Gosport in the Summer of 1963. They passed by a naval shipyard and noticed a beached and apparently discarded mini (aka: one-person) submarine in the assembly yard. The yard gate was open, so the guys checked out the sub and noticed that it had an open hatch upon which had been placed a fly screen (of the household variety), beggaring the question: "what is as useful as a fly screen on a submarine"??? Ironically, someone had punched a hole through the screen through which a horde of wasps had flown in through the hatch and nested. The thought came to mind of how annoying it would be - after closing up the submarine - to have the wasps buzzing around inside the sub... Following immigration to Canada in 1975, one of the guys adjusted the saying to: "as useful as a screen door on a submarine" to accommodate Vancouver Island / BC / Canada / North America vernacular (which didn't recognize the term "fly screen").