Simplicity is not achieved by adding simplifications, but by removing complications.
A sampan boat is typical to South East Asian countries, where many seemingly different boat types in several countries appear under the same common name.
"Sampan" literally means "three planks". This explains the many boat types called by the same name. Boats, that at least originally were made of just three planks. So calling Western piroques, batteaus (sharp sterned dory), my "Prism" or my "Dug" sampans would not be incorrect.
The "One sheet Sampan" presented here follows the ideas of a cargo sampan from canals of Vietnam. She exhibits the interesting concave side sections typical to many sampan types. At least to my eye the concavity is typical to sampans :) The concavity of the bottom edges also helps a lot in placing the boat parts on the plywood, as You can see on the drawing below. The convex bottom edges of side pieces match the concave edges of the bottom piece.
One can hardly think of a simpler boat in terms of building ease and materials usage, yet giving a lot of load carrying capacity and stability. She measures 7'4" x 3'3", so she is wide enough to scull. She displaces about 800 lbs just before flooding. At 250 lbs displacement, that is, one person, her freeboard is 7".
Here is the "One sheet Sampan" .hul file for those interested.
Since the boat really consists of only three parts (transoms have been left out as unnecessary complications), plywood cutting is very easy. The boat bottom comes from the middle of the ply, reaching from end to end. The sides are cut in two pieces each. The rest of the ply is used for butt blocks and quarter knees. Not much more than sawdust is left over.
One might ask "why not cut single piece sides, wouldn't that be simpler?" Yes, it would be simpler. But it would limit the bottom plus the side widths to the width of the plywood sheet, 48". A good combination would be bottom 28", both sides 10". But by splitting the sides in two we now will get a bottom of 30", both sides 13", altogether 56". Which is a much bigger boat. In my opinion it is worth doing two butt joints instead of having a too small boat.
One can, of course, do the cutting "other way round". Make the sides out
of single pieces, and have the butt seam on the bottom.
Or If You want to spare two sheets, You can make a sampan without any
butt seams. Take the bottom measurements from the upper diagram,
the side measurements from the diagram below.
The building sequence is simple and straight forward.
First draw lines to divide the plywood sheet into eight equal squares, each 24" x 24". Measure and mark points A, B, C, D, E and F on the lines according to the measurements given in the drawing above. 

Nail two small nails at points A and B. Put a thin batten above the nails, pull the center of the batten towards You until the edge of the batten reaches point C. Draw the curve ACB along the batten. 

Nail a nail at point D. Bend the batten between the nails at D and B in such a way, that it crosses the plywood edge at right angles at point F. Draw the curve DBF along the batten. Mark 4" wide butt blocks at the center line of the plywood (drawn in pale blue in the drawing above). 
Repeat the procedure for the curve DAE.
Repeat the whole A to F procedure on the other side of the plywood.
All lines marked on the plywood. 

Pieces sawn along the lines. 

And rearranged to "boat shape". 
And assembled into a boat.
The sides were first put together with butt blocks, then the bottom and sides using the "2 x 2 blocks and drywall screws" method. The internal distance between the tops of sides in the middle of the boat is 38 1/2", set this with a piece of board.
The gunwales, and strips in place of transoms are 1" x 1" pine, the seat a length of 1" x 8" just glued between the sides. The quarter knees have been glued on top of the gunwale battens.
Paintwork finished, ready to go on a maiden voyage. 

But what's stalling her? 
:) Did I manage to fool You? But mind You. Making a half size model is just as much work as making a full size boat, making a smaller model is much more work. So If You want to build a boat, the easiest way is to build a full size boat to start with. 