Does anyone recognise this weird keel?
OK, so I decided to do some digging on this. The basic design is credited to Warwick Collins.
Below is a quote from Robert Perry (IMHO one of the leading experts in sailing yach design)
"These tandem keels have been around for years and they do have some structural and pragmatic advantages but remember, there is no substitute for draft when it comes to performance. Of course, any boat with its keel imbedded in the mud is very slow. Curiously, the drawings show a deep rudder that goes with both keels and the rudder draws more than the shoal keel. I hope this is a drafting error."
Here are some other links that may shed some light on the subject:
Looks like this is an interesting subject. In addition, I found references to boats with this keel sailing at anchor. With the european prediliction to stranding a boat for bottom work, it was noted that with this keel, you need to have the boat hoisted to get to the large lower surface of the wing.
It seems that the common opinion is that the Warwick Collins keel is one of the better attempts at regaining the performance lost when one goes shoal draft.