The topic of keels seems to roll around now and then, but this latest info on the topic of water inside the M23 keel has me wondering.....is there a built in cavity above the ballast and below the cabin sole....basically a sealed up dead space that leaves the factory empty, but somehow fills with water over time? My M17 does not have a bilge. The cabin sole next to the CB trunk and under the cockpit is flush clear across. If the entire keel cavity is not full of ballast....there is dead space in there. If so....it could be water that causes keel problems and maybe not rusting ballast. Imagine if the top half of the keel was full of water and it froze? With no place to go, it's going to push the CB trunk out. The ballast may still be encapsulated and doing no harm. Perhaps what is needed in this situation is a keel drain plug? Something you pull out at the end of the season?