Fuel economy due to improvements in ship hull surface condition 1976–1986

Powering

“…Figure 5.115 , which is taken from Townsin (1986) shows the scatter that can be obtained over a sample of some 86 surveys conducted over the two-year period 1984/85.…”

“…In each of the twelve regions defi ned by the matrix on each surface of the blade several roughness measurements should be taken in the direction of the fl ow and widely spaced apart. A minimum of three measurements is recommended in each patch from which a mean value can be taken, Townsin et al (1985) . Townsin et al (1985) established a valuable and practical basis upon which to analyse the effects of roughness on the hull and propeller of a ship.…”

“…A minimum of three measurements is recommended in each patch from which a mean value can be taken, Townsin et al (1985) . Townsin et al (1985) established a valuable and practical basis upon which to analyse the effects of roughness on the hull and propeller of a ship. In this analysis they established a set of generalized equations, the derivations of which form the basis of this section.…”

“…In the case of Equation (5.125) for the propeller penalty, the propeller roughness effects ( Δ K Q /K Q ) and ( Δ K T /K T ) can be estimated from Lerb's equivalent profi le method, from which the following relationship can be derived in association with Burrill's analysis: For the hull roughness contribution, Townsin et al (1985) shows that by assuming a constant thrust deduction factor and employing the ITTC 1978 formula for wake scaling such that w t w t C C k C C where P D is the delivered power at the propeller, C T is the ship thrust coeffi cient, C F is the ship frictional coeffi cient, C FS is the smooth ship frictional coeffi cient, J is the advance coeffi cient, P is the propeller pitch, D is the propeller diameter, Δ c d is the change in reference section drag, coeffi cient, c 1 is the reference section lift coeffi cient, Δ C FT is the increment in ship skin friction, coeffi cient in trial condition.…”

Low Friction Fouling Control Coatings: An International Paint Perspective

“…International Paint turned to the experts in marine naval architecture at the Ship Performance Group at Newcastle University for help and guidance. Over the period from 1976 to 1989, International Paint sponsored 3 research studentships conducted by Byrne 11 , Svensen12 and Medhurst13 under the supervision of Professor Robert Townsin.The notable highlights of this work have been published in a series of papers by Townsin, Byrne, Svensen and Milne14,15,16,17 . The work established a direct link between the Average Hull Roughness (AHR) attributable to the coating system and ship performance.…”