It could be that there is a clogged limberhole keeping the water from draining, or it may be that you'll have to take a sponge and bail it out First, re-bed the stanchion. Then get rid of the water (sometimes you can use a wet or dry vac, but a sponge will do it eventually, for a bailer.) If there is a plugged limber hole, clean it out with a length of 7x7 small gauge rigging
wire, which is quite flexible, great hose cleaners, too. Dusty bilges are a worthwhile goal.