I can imagine that being on the bottom of most canals and adding quite a bit of drag. May just be the close up shot giving the impression though. Does it clear the hull on full lock ok?
Its only an inch below the skeg. It will miss the hull on full lock. How much drag will 4mm of aluminum plate cause at 4mph plus it could make the prop more efficient being enclosed. The plates are angled at the front the same as the skeg so it can ride over any debry and kick the leg up if its something large and heavy protecting the prop.