Sedge is a 15' outboard powered punt designed in 1936 by William Atkin.
from the Atkin website: Sedge will drive easily up to 10 m.p.h.; 8 m.p.h. is her best speed, and this requires only modest power. The choice of a suitable outboard motor is so much a matter of personal preference that I shall not specify one.
in order to achieve the stated performance, what size outboard would you recommend? would 10hp be enough, or could a person even get away with something smaller? it looks like a good design for inland rivers and small lakes.