The reason is not the traditional superstition associated with the number - but the result of one of the saddest tragedies to befall a Clyde-built vessel.
The granite drinking fountain in Elder Park, Govan, is a poignant reminder of the disaster which killed 32 men on board.
During the First World War the massive K13 - described as a super-submarine - had been built at the Fairfield shipyard in Govan.
It had just completed sea trials on Gare Loch where it gained distinction as the world's fastest submarine, having covered the measured mile at a record 23 knots.
On the morning of January 29, 1917, she submerged with her crew of 53 officers and men, 14 directors and employees of Fairfields, 13 civilians and two Royal Navy observers.
K13 was supposed to "trim level" at 20ft below the surface but, in layman's terms, she simply kept sinking, to the horror of those on board.
The vessel's commander took the drastic step of closing the watertight door to the stern. It meant that the 31 men trapped behind died of either asphyxiation or drowning.
K13 kept diving until it settled on the seabed 50ft down. One other man, a Naval officer, was killed during a failed rescue attempt.
It was something of a miracle that the remaining 46 on board survived. They were rescued after an incredible 57 hours underwater when an oxy-acetylene torch was used to cut a hole in the vessel's side.
The memorial, across the road from the old Fairfield yard, reads: "Sacred to the memory of those named who lost their lives in HM Submarine K13 in the Gareloch 29th January 1917."
A plaque at the bottom of the statue, added in later years, reads: "In memory of all Allied submariners W W ll. Still on 'patrol' by families and friends."
The fountain is topped by a crown and has an anchor carved into the granite.
K13 was later re-fitted and became K22 - but the number 13 has never again been given to a Royal Navy submarine.