Illustration of tractor with lines showing measurement. a)Wₑ = roughly width of the unit b) target Wₑ = 2×N c) wetted width of single pass, and two adjacent passes

Figure 4. Determination of a.) effective width (Wₑ) for low-profile-type hose drag units; b.) target effective width for a 2 nozzle boom example, and c.) eld-determined effective width for boom-type hose drag units.