Over the years I have had to fix innumerable problems with life line stanchions and their bases. Deck leaks, bent stanchions, distorted bases. Nearly all of them have been owner caused in one fashion or another.
Sometimes it is as simple as hitting a fixed dock at just the right height and angle and a stanchion gets bent. More often though stanchions are bent by people using them to pull themselves aboard in the process torquing the base fasteners so they eventually leak.
Some boats have base designs that are worst than others in that some designs provide more surface area to distribute the forces that are applied but I have to say the ones pictured here are pretty small and so an inward force applied to the top of the stanchion applies a lot of point force to the deck causing the hole in the deck as seen in photo 1.
In all fairness the designer of the deck pictured here is somewhat to blame as at the stanchion position on deck there is only 3/8″ of glass and no backing plate just a fender washer.
On cruising boats a frequent cause of damage to stanchions, stanchion bases and their fasteners is fuel and water jugs lashed to a plank running between stanchions, especially those located close to the bow. Here a good wave can apply enough force to bend stanchions and distort fasteners on stanchion bases. Stanchions were never designed to support this type of load.
If the boat that had the pictured deck damage had had jugs lashed across these stanchions and ended up with two holes in the deck they wouldn’t have had a big enough leak to sink the boat but it would have resulted in some very wet berths and settees, if the damage in the photo had happened on the other side of the boat it would have flooded out the electrical panel.
I realize many cruisers feel they need to carry extra fuel and sometimes water, but carrying it on deck and lashing it to stanchions is not a good choice. Best example of why not comes from the Captain of a large Catamaran I met in the Bahamas. It was a charter cat and was traveling from Georgetown Exuma to the Virgin Islands. He had 15 yellow 5 gallon fuel jugs lashed across the transom some 4′-5′ off the water. I asked him why so much extra fuel, his reply, “well we might have to motor the whole way there”. We talked about the potential for a wave to clean those jugs off the deck, “won’t happen” was his reply. About a ten days later he was back in Georgetown sans fuel jugs and reeking of diesel. I asked him what happen, he said “well that big wave we talked about before I left, it hit us in the middle of the night with the cabin door open, the wave broke 10+ of those 5 gallon plastic jugs and salt water washed the fuel down below, we have been trying to clean it up for a week!” He swore he would never again carry extra fuel on deck in jugs, it is just not worth the potential problems!