the perfect 20'''' cruising boat?
But gravity only works to keep the swing keel down as long as the boat is right side up!
Should you take a knock down with the keel not locked down, not only could you have a 400 or more pound keel swinging back up into your boat, taking out your trunk, but you also loose all of your righting moment!
The San Juan 21 Class Association requires racers to keep their swing keel locked down when racing for safety (but also presumably to make sure no one sneaks their keel up on the downwind legs).
Some San Juan 21 sailors have apparently experimented with various types of shear pins for the locking bolt, such as wooden dowels, so that if they hit a rock the pin will break and the keel will kick up out of harms way.