1. Andrews RESISTANCE CHARACTERISTICS FOR HIGH SPEED HULL FORMS WITH VANES 1
Resistance Characteristics For
High-Speed Hull Forms with Vanes
Iruthayaraju Andrews2
(SM); Venkata Karthik Avala2
(SM); Prasanta K Sahoo1
(M); Sudarshanaram
Ramakrishnan2
(SM)
1
Associate Professor in Department of Marine and Environmental Systems, Florida Institute of Technology, Melbourne, Florida
2
Graduate students, Department of Marine and Environmental Systems, Florida Institute of Technology, Melbourne, Florida
ABSTRACT
In this paper an attempt has been made to investigate the resistance characteristics of high-speed round bilge hull
forms fitted with a vane in the stern region of the vessel. The Hull Vane ®
is a fixed foil located below the waterline,
aft of the stern of the vessel. The Hull Vane®
reduces the generation of waves and the vessel’s motions in waves. The
focus of this paper is to compare the total resistance of a single model from the AMECRC series of round bilge hull
forms with and without Hull Vane®
attached to the hull.
KEYWORDS
Hull Vane®
; Resistance; Computational Fluid Dynamics
(CFD); Round bilge Hull;
NOMENCLATURE
CB Block co-efficient
Fn Froude number
Fn▽ Volumetric Froude number
RT/ Resistance/weight
INTRODUCTION
As international shipping started to sail into a world of greener
ships with lower carbon emission and better fuel efficiency,
steps are taken in the form of new technologies and new
designs to improve the hydrodynamic efficiency of ships. In
order to make the existing ships more fuel efficient, research is
being carried all around the world to improve the hull form by
modifying the forward and aft regions of the hull.
BACKGROUND
Considerable amount of research has been conducted in the
past on stern appendages such as trim tabs, stern wedges, stern
flaps, interceptors and transom wedges. All of these have
proved to be able to reduce the overall resistance of a vessel by
reducing its running trim. In a study conducted on stern
wedges by Karafiath and Fisher (1987), it was shown that a
reduction of running trim of up to 2.0 degrees could result in a
2% of saving in fuel consumption. Cusanelli and Cave (1993)
investigated the application of stern flaps as a retrofit on US
Navy vessels and found a reduction in power which resulted in
reduced fuel consumption and increased top speed. In a later
study by Karafiath and Cusanelli (1997) on integrated
wedge-flap design, a reduction in power of 11.6% was
observed, while a wedge-only configuration lead to a power
reduction of 6.2%. Tsai and Hwang (2004) studied interceptors
and found that these can be used to reduce the resistance of
planning hulls.
In line with the above research, van Oossanen (1992) invented
the Hull Vane®
, a fixed, resistance-reducing foil situated below
the water line, aft of the stern of the ship. Uithof, et. al (2014)

2. Andrews RESISTANCE CHARACTERISTICS FOR HIGH SPEED HULL FORMS WITH VANES 2
indicates that extensive research using CFD computations,
model tests and sea trials were conducted and found that the
reduction in resistance can be up to 26.5% on ships running at
Froude number between 0.2 and 0.7. The current paper
attempts to compare the total resistance of a single model from
the Australian Maritime Engineering Co-operative Research
Centre (AMECRC) series of round bilge hull forms with and
without Hull Vane®
. Analysis of the resistance characteristics
has been carried out in CFD and compared against the
experimental tank test data of the AMECRC series.
AMECRC SERIES
The AMECRC systematic series, Sahoo, Doctors and Renilson
(1999), of hull forms were developed based on the high speed
displacement hull forms (HSDHF) systematic series.
AMECRC systematic series consists of 14 models. The length
of all models was 1.6 m. The main parameters of the parent
model of AMECRC series are: L/B = 8.0, B/T = 4.0 and CB
= 0.396. For the purpose of this paper, model 13 of the
AMECRC series was chosen and parameters of the model 13 is
shown in Table 1 below.
Table 1: Parameters of AMECRC model 13
Model No 13
L/B 6
B/T 3.25
CB 0.45
Model Disp.(kg) 15.784
L/∇1/3
6.379
HULL VANE® - THEORY
A Hull Vane®
is a wing structure horizontally placed below the
stern of the vessel. The flow around the vane develops a lift
force as well as a forward thrust force. This reduces the
resistance which results in fuel savings. The various forces
acting on the vane are illustrated in Figure 1. It has four
different effects on the vessel which are thrust force, trim
correction, reduction of stern waves and reduction of motions.
The Hull Vane®
was found to be most effective in the non-
planning regime, at Froude numbers between 0.2 and 0.7.
Since the frictional resistance is more dominant below the
Froude number 0.2, addition of a Hull Vane®
to a vessel which
increases the wetted surface area also increases the frictional
resistance compared to the vessel without Hull Vane®
. Beyond
Froude number of 0.2, the pressure resistance becomes a
dominant component. Since the Hull Vane®
decreases pressure
resistance, likely gains are obtained in the Froude number
range of 0.2 to 0.7. At higher Froude numbers, the lift force of
the Hull Vane®
creates a bow-down trim which is not
desirable.
The Hull Vane®
is generally designed and optimized for the
cruising speed or maximum speed depending on the vessel’s
operating profile. Also, the shape of the stern of vessels which
have flat buttocks are ideal for fitting the Hull Vane®
ensuring
a uniform flow to it.
Table 2: Particulars of Hull Vane®
Figure 1: Schematic representation of various forces on the
Hull Vane®
FINETM/MARINE MODEL SETUP
FineTM
/Marine is an integrated computational fluid dynamics
software environment for the simulation of mono-fluid and
multi-fluid flows around ships, boats or yachts, including
various types of appendages. It is a commercially available
package and is used for generating the unstructured hexahedral
mesh and solving the steady flow. The model setup is used for
analyzing the bare hull model 13 of the AMECRC series with
and without Hull Vane®
for Froude numbers 0.5, 0.6, 0.7. The
hull is free to trim and sink, using the 6 degrees of freedom
solver, allowing the hull to surge, sway, heave, pitch, yaw and
roll.
The simulation is started at zero speed after which the speed is
gradually accelerated to the final velocity. The "volume of
fluid" method is used to account for the free surface (i.e. both
water and air flows are solved), for which the parameters are
given in the Table 3 below. The free stream turbulence
quantities were initialized using the reference length and
velocity. Wall functions were used to simulate the flow in
regions very close to solid walls, reducing the mesh density
requirements in the boundary layer. The physical parameters
used for the solver is given in Table 3 below:
Profile NACA 4412
Span 0.224 m
Chord length 0.032m
Wetted surface area 0.01489 m2
Position
LE- X -0.032m
LE- Z -0.048m

3. Andrews RESISTANCE CHARACTERISTICS FOR HIGH SPEED HULL FORMS WITH VANES 3
Table 3: Parameters used in the computation
Main particular of the model
Length of water Line (LWL) 1.6 m
Wetted Surface Area 0.4431 m2
Displacement 16.218 kg
Displacement volume 0.01582 m3
Type of mesh Unstructured
(Trimmed )
Domain Physics Homogeneous
water/Air multiphase,
SST k-ω Turbulent
Model
Initial Physics
Pressure Hydrostatic pressure
Volume Fraction Air - Volume
Fraction of lighter
Fluid
Water - Volume
Fraction of Heaver
Fluid.
Gravity In Z direction -
9.81m/s
Boundary Physics
Inlet velocity at that
Froude Number with
defined volume
fraction
Outlet Pressure outlet
Hull and Hull Vane® ®
Wall with No slip
condition
Symmetry plane along the center line
of hull
Fluid Properties
Density of water 1025 kg/m3
Dynamic viscosity 1.21734*10-3
N-s/m2
DOMAIN AND BOUNDARY CONDITIONS
The domain around the hull is constructed such that the
boundaries do not influence the results. Only half of the ship
was modelled in order to reduce computational time. The
dimensions of the computational domain around the hull are
given in Table 4.
In the symmetry plane a mirror boundary condition was
applied and on the top and the bottom of the domain the
pressure was prescribed. All other domain faces have
external/free-flow boundary conditions with a prescribed flow
speed of 0 m/s.
Table 4: Limits of Domain
MESH GENERATION
The domain volume is divided into small cells to generate the
mesh. The largest cells on the hull are approximately ∆(X, Y,
Z) ≈ 0.0016 m in size. In areas with large curvature and small
features, cells as small as ∆(X,Y,Z) ≈ 0.000098 m were used to
ensure that flow features have a good resolution. Extra cells
were added perpendicular to the hull surfaces to ensure a good
resolution in the boundary layer. The first cell near the wall
was set to have a size of about 0.00064 m, such that its non-
dimensional distance (y+) to the wall was approximately 30.5.
Cells near the air-water interface were refined to have a size of
0.0016 m in z-direction. The following figure shows the mesh
on the surface of the hull.
Figure 2: Meshed model - side view
Figure 3: Meshed model showing Hull Vane®
Figure 4: Meshed model - stern view
X (longitudinal) -4.800 m 3.200 m
Y (beam) 0.000 m 3.200 m
Z (height) -3.200 m 0.800 m

4. Andrews RESISTANCE CHARACTERISTICS FOR HIGH SPEED HULL FORMS WITH VANES 4
Figure 5: Meshed model - bow view
PREDICTION AND EVALUATION
The RT/ value of the model obtained through CFD
simulations is compared with the actual experimental value of
bare hull. The results obtained are for the case of three
different velocities corresponding to Froude numbers 0.5, 0.6
and 0.7. The physics model used was an implicit unsteady,
Eulerian multiphase, standard k-ε turbulence model with wall
functions. Table 3 shows the % difference between the
experimental and CFD results. The error comparison between
the CFD (FineTM
/Marine) and the experimental data shows an
average difference of 5% in RT/ value for the corresponding
Froude numbers 0.5, 0.6, 0.7.
Table 5: Resistance data for different Froude number
The difference is much less when only the resistance values of
CFD and experimental data are compared. But, since there is
difference in testing parameters like displacement of models
and density of fluids, RT/ values were considered to be
appropriate for comparison.
Figure 6: CFD and Experimental data for bare hull
RESULT
The 1.6 m model of the AMECRC series was run for Froude
numbers of 0.5, 0.6 and 0.7 with the Hull Vane®
attached to it.
These results are compared with the bare hull resistance of the
model from CFD and the difference is calculated as a
percentage.
The comparison between the resistance of the bare hull with
and without Hull Vane®
indicates a reduction in resistance for
the model with Hull Vane®
. The resistance values are
compared here as RT/ values similar to the previous
comparison. The testing parameters and conditions are same
for the CFD runs.
Table 6: Resistance data of model with and without hull
vane using CFD
0.06
0.07
0.08
0.09
0.1
0.11
0.4 0.5 0.6 0.7 0.8
Resistance/weight
Froude Number
CFD vs Exp
CFD Exp Value
Froude
number
Volumetric
Froude number
FineTM
/Marine
CFD Results
Exp.
Results
%
difference
Fn Fn▽ RT/ RT/
0.5 1.263 0.06247 0.06531 -4.54%
0.6 1.515 0.08297 0.08789 -5.92%
0.7 1.768 0.09775 0.10263 -5.21%
Froude
number
Vol.
Froude
number
without
Hull
Vane®
With
Hull
Vane®
%
reduction
Fn Fn▽ RT/ RT/
0.5 1.263 0.06247 0.05465 -14.32%
0.6 1.515 0.08297 0.07507 -10.53%
0.7 1.768 0.09775 0.09028 -8.05%

5. Andrews RESISTANCE CHARACTERISTICS FOR HIGH SPEED HULL FORMS WITH VANES 5
Figure 7 Resistance data for the model with and without
Hull Vane®
using CFD
DISCUSSION OF THE RESULTS
The results obtained are discussed in the following part.
With respect to the comparison of bare hull resistance between
experiments and CFD it was observed that RT/ values was
lower by around 5% for all Froude numbers tested. It can thus
be assumed that CFD predicts reasonably well against
experimental data for bare hull.
The next step was to analyze RT/ against CFD results when
the vessel is fitted with a vane. It can be seen from Table 6 that
the hull fitted with a vane shows substantial reduction when
compared with that of a bare hull. The percentage reduction
varying from 8 to 14% appears remarkable and would certainly
project considerable reduction in fuel consumption over the
life of the vessel.
CONCLUSION
In this paper the results of an investigation into the effect of
adding a Hull Vane®
on the resistance of high-speed round
bilge hull form from AMECRC series is presented. The
difference in resistance results obtained from experimental data
and CFD (Fine/Marine) for 1.6m model is also presented.
The addition of Hull Vane®
shows a significant reduction in
the total resistance of the model. A Hull Vane®
is optimized
for required speed and it is to be noted that a limited number of
simulations were carried out to get these results. Further work
on Hull Vane®
optimization may improve the resistance
reduction. Likewise, further work for the full-scale vessel is
likely to result in an improvement of the performance of the
Hull Vane®
due to the lesser effect of frictional drag on it.
Future work shall be carried out to see the effects of the Hull
Vane®
on viscous and wave resistance of the model separately.
ACKNOWLEDGEMENTS
The authors would like to thank Van Oossanen Naval
Architects and Florida Institute of Technology for their support
and encouragement through the course of this research work
without which this paper would not have seen the light of day.
REFERENCE
1. Wang, C.T., “Wedge Effect on planning hulls,” J.
Hydronautics 14, no. 4 (1980).
2. Karafiath, G., and Fisher S.C., “The effect of stern
wedges on ship powering performance,” Naval
engineers Journal, May 1987.
3. Cusanelli, D.S., and Cave W.L., “Effect of Stern flaps
on powering performance of the FFG-7 Class,”
Marine Technology 30, no.1, January 1993.
4. Cusanelli, D.S., and Karafiath G., ‘Integrated Wedge
Flap for Enhanced Powering Performance’, FAST’97,
Sidney, Australia, July 1997.
5. Cusanelli, D.S., and Karafiath G., ‘Advances in Stern
Flap Design and application’, FAST 2001,
Southampton, UK, September 2001.
6. Seo Kwang-Cheol, Gopakumar N., and Atlar M.,
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devices in fast speed vessel’, J. Navig. Port Res., 37,
no.2 (April 2013): 137-142.
7. Tsai, J.F., Hwang, J.L., and Chou, S.K., ’Study on the
Compound Effects of Interceptor with Stern Flap for
two mono-hulls with Transom Stern’, Oceans ’04,
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8. Uithof, K., P. van Oossanen, N. Moerke, van
Oossanen P.G., and Zaaijer K.S., ‘An update on the
Development of the Hull Vane® ,” HIPER 2014,
High Performance Marine Vehicles, Athens,
December 2014.
9. Sahoo, P.K., Doctors L.J., and Renilson M.R.,
"Theoretical and experimental investigation of
resistance of high-speed round-bilge hull forms,"
FAST99 Fifth Int. Conf. on Fast Sea Transportation,
Seattle, (1999): 803-814.
0.04000
0.06000
0.08000
0.10000
0.12000
0.40 0.50 0.60 0.70 0.80
Resistance/weight
Froude Number
Resistance data comparison
with Hull vane
without Hull vane