The Cutthroat Flume has a flat floor throughout the flume and has an hourglass shape when viewed from above with the shorter section upstream.

With flat walls, the flume's converging section is 1/3^rd the length of the flume, with walls that contract at a uniform 3:1 ratio.  

Unlike many other flumes, the Cutthroat Flume lacks an extended throat – hence the name “Cutthroat”.  The converging section walls narrow until they reach the throat, at which time they then immediately begin to expand in the diverging section.  

Like the converging section, the diverging section walls are flat and diverge at a constant ratio (6:1).  The diverging section is 2/3^rd the length of the flume.

Two types of Cutthroat Flumes have been designed:  Rectangular and Trapezoidal.  Both types follow the general configuration laid out above.  The difference is that the Rectangular Cutthroat Flume walls are vertical, and those for the Trapezoidal Cutthroat Flume angle out (like a Trapezoidal Flume).