Power versus Speed for Shallow Draft Navigation

Abstract

A model is developed for estimating the applied power of a tow as a function of tow speed through water, tow size, tow integration, local depth, channel size, and whether the towboat has Kort nozzles or open wheel propellers. The model computes the total resistance of the tow by considering friction resistance, resistance due to water level drawdown, form (pressure) resistance, and the effects of shallow water and size of the channel cross section. The effective push of the towboat is equated to the resistance, and the applied power is determined from empirical relations developed for typical towboats. Comparison with observed tows shows that the model provides a reasonable estimate of the applied power.