The problem is the length of the life line stanchion post puts a lot of strain on the base. Probably the most cyclical strain of anything on the boat except the chain plates. The constant working of the stanchion base under these cyclical loads tests any caulk. The problem becomes an issue when any of the fasteners pass through a cored deck. The core will compress with heavy loads and really work on the tenacity of the caulk adhesion to the deck and stanchion base. The cure is to use a Dremel 199 bit in a Dremel tool, rout out the core, fill the puka with thickened epoxy and redrill the holes. This will stop the core compression and core rot from the breakdown of the caulk. Have used good old LifeCaulk for way too many decades without problems once the core issue is dealt with.