What I am starting to learn is that no two Ariels or Commanders are exactly alike. For example my commander had the foam aft of the ballast and fiberglassed over. Commander 227 tells me his had neither. His was wide open. And in just the few commanders I have personally seen all had some differances in how they were built. All similar but all differant.

When I took all the foam out of my keel the fiberglass on the sides was in my personnal opinion very thin. the sides would flex very easily. Which they did as I scraped off the foam that stuck to them. And this is one of the lifting points for the boat so just to be on the safe side I decided to strengthen the area with a bulkhead. My personality pushes me to eliminate any potential for failure so I added the bulkhead. Your boat may not it.