There seems to be some debate as to the origin and description of a Yawl, undoubtedly it's a two masted craft, the name of which may or may not have evolved from the Dutch Jol or Scottish Yole.
The position of the mizzen mast astern of the rudder is said to differentiate a yawl from a ketch (also twin masted), but it's hard to see how that might be achieved on a transom hung rudder with no counter. In US naval speak a yawl boat might refer to a rowing boat that rests in davits at the stern of a ship.
Whatever the description this is one pretty, open boat, about 16 to 18 feet long, given the absence of a boom, it may well be log rigged with a bumpkin or sprit for the mizzen. I'd like to see it under sail.
Seen on a mooring at Keyhaven.