Trans RINA, Vol 152, Part B2, Intl J Small Craft Tech, 2010 Jul-Dec


CHARACTERISTICS OF A SERIES OF HIGH SPEED HARD CHINE PLANING HULLS – PART 1: PERFORMANCE IN CALM WATER.


D J Taunton, D A Hudson and R A Shenoi, University of Southampton, UK (DOI No: 10.3940/rina.ijsct.2010.b2.96)


SUMMARY


A new series of high speed hard chine planing hulls was designed to study their performance in both calm water and waves. This study was undertaken to determine the influence of hull design parameters such as length-displacement ratio, static trim angle and radius of gyration on the performance of the people on board these craft when travelling at high speed in waves. The series designed extends the speed range for which data are available for planing hulls.


This study summarises the calm water performance of the vessels. Resistance, dynamic trim angle and dynamic sinkage are measured for the series and presented together with an uncertainty analysis of the experimental data. The dynamic wetted surface area of each hull was determined and is included in the data presented. An example of the standard ITTC scaling procedure for high speed marine vehicles is given with a discussion of the impact of including spray resistance using Savitsky’s whisker spray drag formulation.


NOMENCLATURE β


Δ


θV ∇ λ


B


CΔ Cv FrL Fr∇


LC LK


Deadrise [o] Displaced weight [N]


Dynamic trim angle [degrees] Displaced volume [m3] Ship scale factor Beam [m]


Load Coefficient = Δ/(g ρ B3) Speed coefficient =V/(gB)0.5


Length Froude Number = V/(g L)0.5 Volumetric Froude number = V/(g ∇1/3)0.5


G Acceleration due to gravity 9.80665m/s2 L


Length over all [m]


Wetted chine length from transom [m] Wetted keel length from transom [m]


LM Mean wetted length [m] LCG Longitudinal


R* Re


SV T


V Zv


Resistance component [N] Reynolds’ Number


transom


Dynamic Wetted surface area [m2] Draught [m] Speed [m/s]


Dynamic sinkage at LCG [m] 1 INTRODUCTION


In recent years the operation of high speed planing craft for military, commercial and leisure use has increased. With the development


of light weight engines and


propulsion systems typical operating speeds are now higher. Research into materials and structures has led to the development of stronger hulls,


often making the


limiting factor for operation the people onboard these craft. Surveys of the operators of high speed craft,


©2010: The Royal Institution of Naval Architects centre of gravity [%L] from


including the one carried out by the US Navy into their special forces has shown a high probability of serious injury [1].


The current study forms part of a wider investigation into the influence of typical hull design parameters on the resistance, seakeeping and performance of the people on board these craft


include the slenderness ratio (L/∇1/3), longitudinal centre of


gravity, load coefficient and radius


in waves. Such design parameters of gyration,


together with design features such as transverse steps. As such the data acquisition and signal processing requirements are scaled from full scale requirements for human factors measurements, such as those described in BS ISO 18431 [2], British Standard 6841 [3] and ISO Standard 2631 [4]. These are consistent with a recent summary document produced specifically for small, high speed craft [5].


This paper presents the calm water performance data for a new series of high speed hard chine planing hulls. The design of the


hulls is experimental investigation undertaken.


described, together with the Data


for


resistance, dynamic sinkage, dynamic trim angle and dynamic wetted surface area are presented in a format suitable for use by designers of such vessels. A full uncertainty analysis of the experimental data is included. Components of resistance are illustrated for one of the models in the series, in order to aid scaling of these data. A worked example is also included, scaling the model data obtained from these experiments to full scale and highlighting the influence of considering the whisker spray drag for planing craft.


2 DESCRIPTION OF MODELS


Experimental data for the calm water performance of systematic series of high speed planing craft are limited and include Series 62 [6], Series 65 [7] and more recently a series based on the US Coast Guard 47ft Motor Lifeboat (MLB) [8]. The availability of seakeeping data


B-55


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