Here is a third picture of that same boat. You can see the plank keel. Notice how slack the bilges are. That makes the boat sit very narrow on the water but has a lot of reserve buoyancy and is very seaworthy and dry for such a little thing. It is possible with a boat as small as that for one person to provide enough movable ballast by scrunching around on the floorboards to balance the boat in enough wind to break the mast out of it. That and the narrow waterline and the water ski style keel is what makes the boat so fast.