the issue

HIGHLIGHTS
A N E W S L E T T E R P U B L I S H E D B Y S S PA S W E D E N A B 5 6 / 2 0 1 2
Contents
2 Deep Green
4 Escort towing and risk control options – assessing the risk of oil spills
6 Wind propulsion – to be or not to be?
8 Spillman – a systematic approach to oil spills in Arctic conditions
10 Local ferries in a city divided by a river
12 Short comments
56/2012
Deep Green
Minesto has developed a new concept for tidal power
plants called Deep Green. Deep Green converts
energy from tidal stream flows into electricity by way
of a novel principle, somewhat similar to the posture
of a wind kite. The kite assembly, consisting of a wing
and turbine, is attached by a tether to a fixed point on
the ocean bed. As water flows over the hydrodynamic
wing, a lift force is generated which allows the device to
move smoothly through the water causing the turbine
to rotate and produce electricity.
My sincerest Season’s
Greetings...
...to all of SSPA’s clients, partners and colleagues in the
maritime society.
Thank you all for the
opportunities given and confidence shown to us working
together with you during
2012.
Enlightened by the activities going on in the maritime
world today I am totally
confident to conclude that
the ocean have had much to
offer the world in the past
but even more for the future.
To safe guard the value
the ocean has to offer, sustainable resource utilization is
preferred and it´s recognized
by a growing number of
stakeholders.
The energy branch continues to explore assets
hidden in the ocean and the
body of knowledge on how
to also harness the formidable power of current and
waves are steadily increasing.
Researcher and engineers are
exploring a variety of ways
to harvest and transform this
power into something that
can greatly benefit mankind
– renewable energy. Although
this field is still emerging, it
has a great potential for the
future.
The shipping industry is
very much focused on green
technology and energy efficiency in order to continue
supporting globalization.
Significant progress has been
made and huge investments
are foreseen in this area in
the future. In order to making
the paradigm shift happen
joint efforts from the stakeholders will be essential.
At SSPA we remain committed doing our best supporting our clients and making a blue sustainable future
come true.
Susanne Abrahamsson
2
The kite consists of a wing, which carries a nacelle and
turbine that is direct coupled to a generator inside the
nacelle. The wing is attached to the seabed by struts
and a tether. The tether to seabed accommodates both
power and communication cables for further connection
to shore. The kite is steered in a predestined trajectory
by means of a rudder and servo system located in the
rear cone of the nacelle along with a control system. The
tether attaches the kite to a swivel mounted on a foundation on the seabed. The kite velocity in the trajectory
is significantly higher than the current velocity. Thus, the
method increases the flow velocity into the turbine with
up to 10 times the tidal current speed.
Ocean Energy
Ocean energy has the potential for providing a substantial
amount of new renewable energy around the world. The
oceans represent a major source of renewable energy.
Different technologies employ different strategies for
harvesting that energy. The main sources of ocean energy
are:
- Ocean currents
- Tidal currents
- Tidal range (rise and fall)
-Waves
- Ocean thermal energy
- Salinity gradients
Deep Green efficiently harvests the energy in ocean and
tidal currents. The Deep Green technology utilises low
T
he kite consists of a wing, which carries a nacelle and
turbine that is direct coupled to a generator inside the nacelle. The
wing is attached to the seabed by struts and a tether.
ILLUSTRATION: MINESTO
A
rtist impression of a Deep Green array. ILLUSTRATION: MINESTO
velocity currents with a velocity of 1.5-2.5m/s as opposed
to other technologies that compete for tidal hot spot
locations where velocities are in excess of 2.5 m/s.
Model scale tests at SSPA
Model scale testing has played an important role in the
development of Deep Green. The hydrodynamic properties and control system have been successfully verified
on a scaled model. Several test campaigns have been
performed in SSPAs towing tank. Various rudder configurations, tethers and trajectories have been tested to opti-
U
nderwater photo of the kite in SSPAs towing tank.
Model scale testing has played an important role in the development of Deep Green. PHOTO: MINESTO
56/2012
Deep Green
J
an Hallander M.Sc.
(1991) in Mechanical Engineering and Ph.D. (2002) in
Naval Architecture from Chalmers has been employed as
Project Manager at SSPA since
1998. He has been involved in
various research and consultancy projects within the areas
of general hydromechanics,
propulsion and underwater
acoustic signatures, especially
with phenomena related to
cavitation and noise induced
by the propeller. He has previously worked on cavitation
noise research at Chalmers.
Telephone: +46 31 772 90 57
E-mail: jan.hallander@sspa.se
M
inesto staff
(Christian Norinder och Patrik
Pettersson) preparing the kite
for the next run in the SSPA
towing tank. Various rudder
configurations, tethers and
trajectories have been tested
to optimise the performance.
PHOTO: MINESTO
mise the performance. Essential parts, like the swivel and
nacelle, have also been verified. Knowledge that is directly
transferable to the full-scale product has been obtained
and implemented in the mechanical design and control
system. “Our design methodology is to perform hands-on
tests in the laboratory and field, rather than spending a
lot of time on computer simulations” says Minesto’s CEO
Anders Jansson.
Tests have been performed both with the model
towed in its tether, as well as captive tests. The first
towed tests were performed with a model that is
slightly denser than water and the tether attached to
the carriage at the surface. In later tests, an attachment
point close to the bottom in combination with a buoyant model was used. In the captive tests, the model
was attached to a six-component balance in order to
measure the forces on the model. These tests play a
fundamental role in the development and verification
of control algorithms for the Deep Green underwater
kite. The next step is to perform cavitation tunnel tests
for verification of the hydrodynamic performance of the
turbine.
In situ tests
Minesto’s CEO Anders Jansson:
“Our design methodology
is to perform hands-on
tests in the laboratory and
field, rather than spending
a lot of time on computer
simulations.”
PHOTO: MINESTO
During winter 2011/2012, a prototype on a scale of 1:10
was tested at sea in Strangford Lough outside the coast
of Northern Ireland. The prototype was the same as the
one used in laboratory tests, but with a longer tether
and different foundation. The focus was on demonstrating that the technology operates efficiently and safely in
the ocean. “In laboratory tests, you have absolute control
of the testing conditions. This is a big advantage, but also
the main drawback. Now, we were able to prove that
Deep Green behaved as expected in an uncontrolled
environment,” says Anders Jansson. The hydrodynamic
properties and control system were successfully verified
on the scaled model. All systems were in proportion to
the full scale, resulting in a massive leap in confidence and
knowledge.
Minesto is now working on the next prototype on a
1:4 scale. It will be installed at sea in the end of 2012 and
will be tested over a period of one year. The main focus
in these tests will be electricity production.
Minesto is pursuing a focused development plan
where the goal is to deploy the first full scale prototype
in 2014, a 3MW Deep Green array in 2015, and increasing to a 10MW array in 2016.
Jan Hallander
MINESTO
Minesto’s technology originates from the wind department at SAAB Group in Sweden. However, because it
was beyond the scope of SAAB’s core business, it was
spun off in the form of Minesto, which was created in
2007.
The company has now grown to 20 employees and
they will soon be 25. It is now the largest ocean energy
company in Scandinavia, according to CEO
Anders Jansson.
In 2010, Time Magazine selected Minesto as one of
the Top 50 Best Innovations in the world and in 2011
Minesto was nominated for Top 15 Utility Solutions in
the USA.
3
56/2012
Escort towing and risk control options
– assessing the risk of oil spills
Escort tugs could help reduce the risk of technical
faults on tankers when they visit ports or are travelling in confined or environmentally sensitive areas. In a
study conducted by SSPA in 2011 on behalf of Nynas
AB, escort towing was compared with other riskreducing measures. It was concluded that, for certain
types of waters and vessels, alternative measures should
be considered to enhance safety and minimize the
risk of serious accidents with consequential oil spills.
A follow-up simulation study of risk control options is
currently underway.
M
aria Bännstrand,
Project Manager at SSPA.
M.Sc. in Shipping Systems and
Technology with a Major in
Shipping Management and
Logistics from Chalmers University of Technology (2003).
Master Mariner (1999).
Employed at SSPA since April
2012, working primarily with
simulation studies and with
projects linked to alternative
fuels. Previous employments include work at sea and as ship
operations manager and as
hull insurance underwriter.
Telephone: +46 31 772 90 70
E-mail: maria.bannstrand@sspa.se
The challenge is to understand why accidents occur,
assess the probabilities and then study potential measures
for mitigating such risks. This is a complicated but vital
task for ensuring that oil transports are conducted as efficiently as possible and at an acceptable level of risk.
Risk control options – low speed…
Escort tugboats are mainly used for guiding tankers
through critical passages and providing assistance in the
event of a technical fault on the vessel. However, this
introduces yet another risk, i.e. that the vessels will collide
due to being in close proximity of one another for an
extended period of time. Speed reduction is, accordingly,
a particularly interesting risk control option because it
allows the bridge team more time to evaluate situations
and take proper action to correct any mistakes or deal
with an equipment failure. Hull penetration is typically
also less extensive for ships that hit ground, provided that
they are travelling at a low speed. However, because drift
angle increases at lower speeds, time is required for making course adjustments. Accordingly, this option is more
suitable in broader fairways.
…enhanced equipment…
Another safety measure is the use of enhanced equipment for improved traffic surveillance, e.g. electronic
charts and AIS that is integrated with radar and ECDIS.
This helps in the selection of optimal routes, where
E
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Time (hrs)
F
requency distribution of time to recovery of main engine
failures. (Ellis, Forsman, Hüffmeier, & Johansson, 2008)
4
there is maximum distance to shallow areas and thus
fewer maneuvers close to shore. The bridge team then
has more time to evaluate complicated situations and
take appropriate action. However, as explained above,
this option is not suitable for vessels travelling in narrow
fairways.
…increased manning and detecting
deficiencies
Another proactive safety measure is to increase the
manning of the bridge when vessels pass through narrow fairways. Adherence to statutory rest periods is also
important. Furthermore, regular reviews of safety records
and management can help detect deficiencies in vessel
maintenance or the organization. Steering and propulsion
redundancy systems can also be useful in the event of
a technical failure. However, a certain amount of time is
required to activate such systems, so this may or may not
be an option (depending on the width of the fairway).
Risk assessment
100
Probability for recovery of failure (%)
rland Wilske,
­Project Manager. He graduated
in 1988 (M.Sc. in electronic
engineering) from Chalmers
University of Technology. After
graduation he worked with research of opto-electronics sensors and software development
of cargo handling systems. In
1994 he joined SSPA and has
since then been involved in
projects linked to development
and use of simulation tools.
Telephone: +46 31 772 90 34
E-mail: erland.wilske@sspa.se
R
eal time simulations can be used for training and
a­ ssessment of how the human factor and technical aspects
impact risk.
Information and knowledge of fairway characteristics is
vital when conducting risk assessment and evaluating
safety precaution measures.
- Fairway dimensions and traffic density determine the
limits of maneuverability. In narrow passages, there are
fewer alternative routes and shorter distances to no-go
zones and other vessels. In wider fairways, where there
is less traffic, the navigator has more time and options
available in the event of a failure.
- Knowledge of the characteristics of the sea bottom in
fairways is also crucial in order to avoid collision with
rocks resulting in hull rips and oil spills.
- Winds and tides must be considered when determining a speed that is appropriate for the fairway width
and acceptable drifting angle.
56/2012
Escort towing and risk control options – assessing the risk of oil spills
Minimum distance to fairway limit (m)
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Nynäshamn
Brofjorden
Göteborg
Oxelösund
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xtent of damage shown via a grounding simulation.
0246810
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Fairway distance (nm)
M
aneuverability limits.
- Wave effects – if the ship hits ground in rough sea
conditions, there is a higher risk of incurring severe
damage.
- Navigational difficulties – certain tools can assist with
positioning in different visibilities.
Real-time simulations
T
ug in escort operation.
PHOTO: CHRISTER GREEN
Real-time simulations with full-mission bridge simulators
are a useful tool for hazard identification, obtaining an
overview of risks and assessing risk-control options. For
example, they can be used to assess (and train) tanker
operators, vessel traffic services (VTSs) and the suitability
of using escort tugs to coordinate actions in a failure
situation. However, real-time simulation also has some
drawbacks, i.e. because it is very time-consuming, it is not
frequently used. So, conclusions are based on very few
scenarios. But, high-fidelity, real-time simulations are also
very valuable because they enable experts from various disciplines to cooperate in assessments and better
understand how the human factor and technical aspects
impact risks.
Compressed time simulations
In compressed time simulations, the ship is controlled
by a track-keeping algorithm to follow a designated
route and maintain a certain speed. Failure scenarios
(such as degradation of main propulsion or rudder) and
navigational errors are introduced and combined with
environmental conditions (tide, wind, current) and traffic.
The human factor and technical aspects are considered
when selecting risk-mitigating actions. With this type of
simulation, it is possible to run numerous iterations and
cover virtually all situations at all positions along the designated route. The simulations also reveal grounding risks
(location and speed) and high resolution bathymetric
data can be used to estimate the damage location and
distribution. The results from grounding simulations are
then compared to actual damage data in order to estimate the extent of damage (e.g. penetration of inner or
outer hull for a double hull tanker). Finally, the simulation
results are projected onto the frequency distribution of
various types of failures to assess the likelihood of an oil
spill for a specific ship type under specified operational
conditions.
Hence, simulations provide a solid basis for assessing
the risk of an oil spill when various risk-mitigating measures are used.
Maria Bännstrand Erland Wilske
5
56/2012
B
jörn Allenström,
Vice President at SSPA. He
graduated (M.Sc.) from Chalmers University of technology
in 1976 and has since been
employed at SSPA except for
two years. He has during the
years been involved in several
research and development projects within the field of hydrodynamics, but most work has
been focused on propulsion
problems.
Telephone: +46 31 772 90 66
E-mail: bjorn.allenstrom@sspa.se
Wind propulsion
– to be or not to be?
Everyone currently involved in the maritime sector is
undoubtedly aware of the continual efforts to reduce
emissions from ships. New regulations, like the EEDI
(Energy Efficiency Design Index for new ships) are
important components of such efforts, even though
it will take years before such mandatory global emission reduction schemes make a noticeable impact on
the environment. However, more immediate results
are already possible to detect from slow steaming. For
example, many ships that were designed for speeds of
around 16 knots are now sailing at much slower speeds,
which saves fuel and reduces emissions. When speed
is reduced from 16 to 8 knots, the fuel consumption is
reduced to 20% or less per time unit, but sailing time
doubles. This results in net fuel savings of around 60%.
This equation applies when sea conditions are relatively
calm. However, in high seas, fuel consumption is much
higher, despite the slower speed. Likewise, when there are
strong beam winds or tailwinds, fuel consumption can be
reduced to nearly zero by using wind propulsion.
What is wind propulsion?
The feasibility of using wind propulsion is being studied
in two research projects, EffShip (Swedish project) and
Ulysses (European project).
Both projects are investigating the use of Flettner
rotors and kites. The EffShip project is also examining a
new type of sail called EffSails, while Ulysses is exploring the use of suction sails. Both of these are rigid sails,
i.e. they are comprised of metal or perhaps a composite
material. Rotors can of course also be manufactured
from either, while kites are made of textiles.
Other textile sail types are being investigated in
research elsewhere, but they are not considered in the
EffShip and Ulysses projects. These studies focus on wind
propulsors that can be “packed up” when there is no
wind or too much wind. For example, kites are taken
down, the EffSail has a telescopic design and may be
folded and the suction sail and rotor can be folded.
Use of kites during tail winds…
The only wind propulsor of the ones studied that can be
considered to be on the market today is the kite. ‘To be
on the market’ means in this sense that there is a number
of them existing on a commercial basis. Studies show that
the kite is a superior wind propulsor in tail winds, as well
as being quite effective in beam winds. From simulations
carried out with SSPA’s inhouse program SEAMAN it can
be seen that even very large ships, like Panamax tankers,
can reach a speed of around 8 knots with a wind speed
of 10 m/s using a 640 m2 kite. Although such large kites
do not currently exist on the market, it is not unlikely
that they will be available sometime in the future. The
potential benefits are significant: using a kite for the entire
Facts
EffShip (Efficient Shipping with low emissions,
www.effship.com) is a Swedish project that is jointly
funded by VINNOVA (the Swedish Governmental Agency
for Innovation Systems), industry and academia. EffShip
is founded on the vision of a sustainable and successful
maritime transport industry – one which is energy-efficient
and has minimal environmental impact. The project has a
total budget around 2 MEUR, and a significant portion is
provided by industry.
T
he EffShip Panamax tanker equipped with
Flettner rotors and EffSails.
The 4 rotors have a diameter
of 4.7 m and a height of 28.2
m, while the maximum height
of the 4 sails are 52 m and
they have a chord length of
17 m. With these sizes, the
rotors and the sails produce
the same wind thrust in beam
winds, however the projected
area of the sails is 7 times
higher.
6
Ulysses (Ultra Slow Ships, www.ultraslowships.com) is a
European funded project with a budget of around 4 MEUR.
The objective of the ULYSSES project is to demonstrate
(through a combination of ultra slow speeds and complementary technologies) that the efficiency of the world
fleet can be increased to a point where the following CO2
targets are met;
– Before 2020, reducing greenhouse gas emissions by 30%
compared to 1990 levels,
– Beyond 2050, reducing greenhouse gas emissions by 80%
compared to 1990 levels.
Flettner rotor is a rotating cylinder that uses the Magnus
effect to create a very high lift force (compared to ordinary
sails).
EffSail is a fixed azimuth symmetric sail that is telescopic
and can be folded. It was developed as part of the EffShip
project.
Suction sails are also azimuth. Compared to ordinary
sails, they have a much higher lift because the boundary
layer is sucked out from the aft part of the wing section.
Kite is, as the word says, a wing shaped kite that is flying
often in a figure 8 (∞) pattern 200 to 300 meters above
the water surface pulling the ship forward.
56/2012
Wind propulsion – to be or not to be?
Simulated fuel consumption for 3500 nm at 10 m/s wind speed
16 knots without wind propulsor
16 knots with rotor
16 knots with EffSail
8.7 to 10.8 knots without wind propulsor,
20% engine power
9.7 to 12.9 knots with rotor, 20% engine power
9.9 knots to 12.3 knots with EffSail, 20% engine power
11 to 12.9 knots with kite, 20% engine power
with rotor and 1 to 20% engine power
with EffSail and 0 to 20% engine power
with kite and 0 to 20% engine power
500
450
400
fuel consumed (ton)
T
he graph shows
calculated fuel consumption
for a Panamax tanker doing a
journey of 3500 nautical miles
in a wind speed of 10 m/s in
different wind directions and
is based on simulations with
SSPA’s in house program SEAMAN. A reduction in speed
from 16 knots to around 8
knots represents a major fuel
reduction, but the journey
then takes 440 hours instead
of 220. Since the engine will
not allow for lower power
outtake than 20%, the speed
never goes under 8.6 knots.
With rotor and sail in operation the speed is often around
12-13 knots. At 16 knots the
additional thrust from the rotors and the sails also offers a
significant fuel reduction, often
around 30%. This ship speed
is too high for the kite at a
wind speed of 10 m/s. Using
the 20% engine power the
kite presents the largest fuel
reduction among these three
wind propulsors in tail winds
(180 degrees). However, for
this condition the use of wind
propulsors offers ‘only’ an additional fuel saving of 15-20 %.
If the engine is stopped then
the fuel consumption using a
kite in tail winds could be zero,
but to reach the port within
440 hours the ship has to use
the engine for around 25%
of the time, with sails or rotors around 50% of the time.
Without the propeller working
even the kite has problems
keeping the ship on course in
beam winds.
16 knots using
engine and
Flettner rotor
or EffSail
350
300
8 knots using
20% engine
and Flettner
rotor or EffSail
or kite
250
200
150
100
50
0
0 30 60 90 120150180
true wind and wave direction (degr.)
journey with a 10 m/s tail wind and speed of around 8
knots would result in fuel savings of almost 100 % for the
propulsion of the ship.
…and beam winds
When there is more of a side wind, simulations have
shown that when the propeller is turned off, relatively
large rudder angles are sometimes required to compensate for the transverse forces acting on the ship. In a
pure side wind without the propeller running it can be
impossible to even keep the course. Accordingly, the best
way to use such winds is to keep the engine running at
around 20% of the maximum power, which increases the
speed by 2-3 knots.
In beam winds – sails and rotor
So, while the kite is regarded to be superior in tail winds,
the sails and the rotor are the best ones in beam winds
and can also operate in conditions relatively close to
the wind. For sails, significant fuel saving can already be
achieved with wind directions of 30-40 degrees from
the bow. Rotors typically require another 10 degrees to
be effective. However, sails have about 7 times higher
projected area compared to rotors and this can impede
sight from the bridge. This could be solved by designing
future sailing ships that have the bridge at the bow.
6 to 8 knots
using 0 to 20%
engine and
Flettner rotor
or EffSail or
kite
Feasibility of wind propulsors
Given the possible benefits, why is the use of wind propulsion still so limited? There are several possible answers
to this:
- To be effective, the wind speed must be relatively high.
As explained above, a wind speed of 10 m/s is adequate for a ship speed of 8 knots. However, for ships
designed and required to sail at twice the speed, 16
knots, a 10 m/s wind speed gives a relatively low wind
thrust especially in tail winds.
- The price of fuel is still not high enough to motivate
retrofitting or even installations on new buildings
of wind propulsors (pay- back time is not attractive
enough). Perhaps this will change in the future, if the
fuel prices will raise considerably.
- There are probably uncertainties about operational
safety when using wind propulsors. What happens if a
kite suddenly dives? Will rotors be exposed to vibrations? Will large sails hinder visibility from the bridge?
If slow steaming predominates in the future, existing wind
speeds worldwide will be suitable for sailing. If fuel prices
rise, pay-back time on an investment in wind propulsors
will become more attractive. Furthermore, technological
solutions will also surely be developed to address and
eliminate uncertainties concerning operational safety.
Björn Allenström
7
56/2012
Spillman – a systematic approach
to oil spills in Arctic conditions
Much effort goes into reducing the risks associated
with Arctic operations and progress has certainly been
made. Accidents resulting in major oil spills must not be
an option. However, if an accident does occur, we still
need a systematic way of dealing with the spill and minimizing the damage. Preparedness is of utmost importance and for this reason, SSPA has developed Spillman,
a tool that enables a systematic approach to oil spills in
Arctic conditions.
V
ictor Westerberg,
M.Sc (2012) Naval Architecture from the Royal Institute of
Technology joined SSPA after
graduation. Active within Arctic
oil spill response as well as ice
management, winter navigational projects and simulations.
Telephone: +46 31 772 91 34
E-mail: victor.westerberg@sspa.se
B
jörn Forsman,
Manager at SSPA, M.Sc. Mech.
Eng. From 1980, when he
joined SSPA. He has been
­active in areas related to
marine environment, oil spill
prevention and spill clean-up.
For the last ten years, maritime safety and risk analysis
have also become important
fields of expertise in his projects as well as in the research
projects that he is engaged in.
He has also been programme
manager for a number of advanced international training
programmes.
Telephone: +46 31 772 90 59
E-mail: bjorn.forsman@sspa.se
PHOTOS: ERLAND WILSKE
8
Spillman uses a wide range of inputs in order to encompass the entire operation – from contingency planning
and emergency preparedness to full operational decision
support, including a safe retreat.
A comprehensive tool
Based on season and area of operation, Spillman collects
data and accumulates necessary knowledge about the
environmental conditions, navigational routes, available
ports (including capacities and infrastructure), local laws
& regulations, and more. Further, by including available
response units, their capacities, locations and performances,
it is possible to determine the level of preparedness for
dealing with a specific spill scenario. Conversely, it is possible to determine the appropriate scope of response units
based on a specific spill scenario, e.g. in permit processes.
Spillman is a valuable asset for both the planning and
execution of operations. The intended users are all entities that conduct operations in Arctic conditions, including
governments as well as rescue and response organizations.
and recovery methods, equipment and crew capacities,
which, unfortunately, often has a negative impact on performance. Prior to all operations, it is necessary to consider and resolve factors such as equipment winterizing,
crew training and the additional ice breaking resources
required for effective ice management.
Further complicating the situation is the remoteness
of most of the Arctic region. The distance to strategic
ports with basic infrastructure is often considerable, so a
well-functioning logistics chain is thus lacking. The operation must therefore be self-supporting, which means that
preparedness and an understanding of the limitations
are critical. Operational limits are set by identifying the
response gaps, which are strongly associated with the
emergency preparedness.
The Arctic conditions
Planning capabilities of Spillman
In many ways, an oil spill response operation in Arctic
conditions differs from such operations in other climates.
The level of complexity is much higher due to low temperatures, the presence of ice and considerable seasonal
variations. This causes variation in oil properties, response
Prior to any Arctic operation, planning is of the utmost
highly important. The aim is not only to perform the
operational task, but also, no matter what happens, to
get there and back safely, to be self-supporting and to
achieve a high level of cost and resource efficiency. A
thorough understanding of the operational limitations
is crucial so that decisions to retreat or abort can be
reached before it is too late. Spillman is a valuable tool
for performing gap analysis, which establishes the operational limitations for each specific case.
The permit process is another important aspect of
operational planning. It involves establishing and producing contingency plans, as well as ensuring that there
is adequate emergency preparedness. Provided with
operational knowledge and a dimensioning spill scenario
Spillman contributes to the planning efforts.
Operational capabilities of Spillman
If a spill does occur during an on-going Arctic operation, it is crucial for the response effort to use methods,
equipment and units with high recovery capabilities.
Spillman considers input data, such as current position,
time, environmental conditions, forecasts and details
about the spill (including available response units). Based
56/2012
Spillman – a systematic approach to oil spills in Arctic conditions
G
eneral flow
graph of Spillman describing
different input, sub-models and
results.
Pre-defined input
on the available response methods and emergency
preparedness, Spillman then generates the window of
opportunity, which refers to the feasible response methods for a specific case, including estimations on method
potentials. Based on the information provided by Spillman,
decision makers are able to appropriately invest time and
energy in mobilizing units and select the best methods
for minimizing the impact of the spill.
User-defined input
Statistics
(Metocean & Ice)
Spill scenario
Infrastructure
Emergency preparedness
Laws & Regulations
Real time conditions
Response Units &
Methods
SPILLMAN
capacities & limitations
Sub-models:
1 External Conditions
2 Oil Properties
3 Response
4 Logistics
5 Evaluation & Performance
• Window of Opportunity – Feasible response methods
• Operation/Recovery Performance
• Response Gap Analysis
Expanding the SSPA Arctic toolbox
With Spillman, SSPA has added yet another valuable tool
to its Arctic toolbox, which already includes such assets
as SEAMAN and IceMaster. These are tools that support
the operational planning process by helping to determine
the requisite ice breaking resources for successful ice
management, as well as assessing seasonal duration. High
operational safety and resource optimization are always
prioritized. Spillman is a valuable, complementary tool
that facilitates oil spill preparedness into the operational
planning and decision support if an accident occurs.
SSPA also recognizes the value of skilled crew members and the important role that they play in making
on-site assessments based on their own knowledge and
experience. Accordingly, this is a valuable input to Spillman
and SSPA has also developed the Oil in Ice Code, which
is a quick and easy way to categorize ice conditions based
on the vast experience of crew members.
Customized solutions
Arctic operations require a customized approach due
to the highly vulnerable environment, remoteness and
severe climate. Prior to or during any Arctic operation,
an up-to-date and easily accessible decision support tool
is a valuable asset for ensuring that there is sufficient
knowledge concerning emergency preparedness and oil
spill response operations. Spillman is tailored to individual
needs and it delivers results in an easy and accessible way
to decision makers.
Victor Westerberg Björn Forsman
9
56/2012
Local ferries in a city divided
by a river
S
taffan Sjöling,
Project Manager at SSPA. He
received his M. Sc. Degree in
naval architecture from the
Royal Institute of Technology,
KTH, in 1996. He has previously been employed at the
Swedish Defence Materiel
Administration, FMV. He is primarily working with concept
design and general naval architecture issues, specializing in
ships stability.
Telephone +46 31 772 91 08
E-mail: staffan.sjoling@sspa.se
A
rtist impression of the river ferry by Designkonsulterna
SSPA has been engaged to help the public transport
authority, Västtrafik, in its procurement of new ferries
for traffic across Gothenburg’s Göta Älv River. There
has been ferry traffic on Göta Älv River since the
1800s and management responsibilities have passed
between a number of different companies over the
years. The current manager, Västtrafik, has opted for a
model whereby it owns the ferries themselves, but uses
a procurement strategy for traffic services.
The aim is for the new ferries to provide commuters
with reliable, year-round transport back and forth across
the river. Ferries provide a link for pedestrian commuters who travel by bus on each side of the river, and they
A
typical route operation profile with
possibility of charging batteries during transit.
Power/ Speed
Speed
Power
D
D
C
Charging
Discharging
Time
10
are also used by cyclists. More and more Gothenburg
residents are biking to work and it is hoped that the new
ferries will help boost this trend even more. They should
have capacity for 300 passengers, of which 80 are cyclists,
and designed with environmental considerations in mind
as well.
Assisting a novice ferry operator
Although Västtrafik is a novice ferry operator, it has nevertheless been eager to meet the various requirements
and demands of its stakeholders in Gothenburg. SSPA
was engaged to help conduct workshops where different objectives were discussed pertaining to the layout
of ferries, safety issues and operating with low emission
propulsion. Based on the input from these workshops, a
set of requirements and priorities were established for
the ongoing project.
Due to time constraints, it was not possible to produce a complete basic design for the ferries. However, a
number of different concepts were produced and used
to ensure the feasibility of the project. The final choice
was a double-ended monohull ferry design with azimuth
thruster propellers. The hull would be constructed of
steel, due to winter operation in ice, with a superstructure of aluminum or some other light-weight alternative.
The passenger deck was designed to accommodate
passengers travelling both with and without bicycles, sharing a single, weather-protected compartment, with quick
turnaround for loading and unloading.
56/2012
Local ferries in a city divided by a river
Propulsion engines for tomorrow’s
development
power during acceleration/deceleration at the end terminals and that power can be generated during transit and
stored in batteries. With such a battery-hybrid system,
smaller diesel generators could be used, resulting in lower
emissions.
One of the challenges of the project was to design ferries equipped with low emission propulsion engines.
The pros and cons of a number of alternatives were
evaluated. It was finally decided to equip the ferries with
conventional diesel-electric engines. This was mostly due
to the uncertainty of new technologies and the need to
satisfy certain regulatory requirements. In order to make
power exchange possible in the future, a direct current
power distribution system was chosen (rather than an
alternating current distribution system). With a direct
current power distribution system, the source of power
can more easily be exchanged or supplemented with
batteries.
Using ferries as a test bench
The design of the ferries should also allow for possible
modification of the power system. However, the details
of such a modification are not currently known. The ferries must be able to accommodate additional weight and
have sufficient space for future installations. A separate
study, also performed by SSPA, investigated possible
developments of the power system to ensure adequate
design margins. One option is to use ferries as a test
bench for new technologies in power generation.
SSPA provided Västtrafik with technical specifications, a basic layout for the ferries and support during
the procurement process, which is currently under way. It
is hoped that a contract will be in place with a shipyard
sometime in the near future.
SSPA is associated with among other things its testing facilities, hydrodynamic knowledge and research. The
above example is yet another area of expertise; perform
requirement analyses, offer design assistance and provide
customer support services.
SSPA eagerly looks forward to seeing these new river
ferries out on the Göta Älv River very soon.
Staffan Sjöling
Different power systems
Super capacitors are energy storage systems that are
particularly suitable for these types of ferries. Super
capacitors are similar to batteries, but they can be
recharged more quickly, i.e. seconds rather than minutes
or hours. This is a major advantage, since ferries only
makes short stops at the end terminals. Furthermore the
distance across the river is short and stops are frequent,
which enables frequent recharging. Another alternative
power system could be a hybrid system with conventional batteries. In this case, diesel-electric engines could
be supplemented with batteries. Ferries require the most
P
reliminary layout of the ferry.
           
Lindholmen
MES
MES
FP
H/C
D
Deck store
Bunker
T-DISPL
Environment
Station
MES
T-DISPL
AP
U
T-DISPL
T-DISPL
Environment
Station
Clean. locker
U
H/C
MES
11
Short
comments
AQUO
SSPA participates in AQUO, a collaborative project funded by the
European Commission. AQUO is
an acronym that stands for “Achieve
QUieter Oceans by shipping noise
footprint reduction.” It has been
funded under the 7th Framework
Program, Theme 7: Transport
(including aeronautics) – Sustainable
Surface Transport. The topic that
this project addresses is: assessment
and mitigation of noise impacts
of the maritime transport on the
marine environment (a coordinated
topic within the framework, Ocean
of Tomorrow).
To some extent, AQUO is a
continuation of another EC project,
SILENV (Ship oriented Innovative
soLutions to rEduce Noise and
Vibrations). However, SILENV
addressed almost all aspects of
noise related to ships: Underwater
Radiated Noise (URN), noise radiated in harbours and noise & vibrations inside ships. AQUO, on the
other hand, is dedicated to noise
impacts on the marine underwater
environment and special attention is
given to cavitating propellers.
The overall objective of AQUO is:
-To assess and mitigate noise
impacts of maritime transports
on the marine underwater environment, mainly for the protection of marine species,
-To support the requirements of
Directive 2008/56/EC (Marine
Strategy Framework Directive)
and related Commission
Decision on criteria for Good
Environmental Status.
At the end of the project, the
main deliverable will be practical
guidelines providing support to
policy makers aimed at meeting
the requirements of the Marine
Strategy Framework directive
(MSFD), including:
-A good knowledge and prediction of the shipping noise level
and spatio-temporal distribution
thanks to a Noise Footprint
Assessment tool,
-Practical and economically feasible design recommendations
for the reduction of underwater
radiated noise (URN), of ships,
-Measures for the mitigation of
impacts from shipping noise on
the marine environment, with
respect to living species.
12
SSPAs main efforts concerning this
project involve:
-Numerical modelling of propeller cavitation and URN by
Computational Fluid Dynamics,
-Model scale investigation of propeller cavitation and URN,
-Full scale observations of propeller cavitation and measurements
of URN.
A coastal tanker will be the target
for all of these efforts. Thus, full
scale result will be compared to
numerical predictions and to predictions by scale model tests.
In the work package, “Guidelines
to reduce ship noise footprint,”
SSPA is involved in the following
tasks: “Effectiveness of solutions to
reduce ship URN” and “Impact of
solutions on fuel efficiency.”
Jan Hallander
Safety upgrade on naval
vessels
SSPA has supported the Swedish
Defense Material Administration
(FMV) in a project to upgrade safety on Swedish Navy “Bevakningsbåt
80” class vessels (22 meter patrol
vessel). The upgrade was done to
meet safety requirements for a
new, increased operational area in
the role as surveillance and border
patrol vessels.
The project initially only included
an upgrade to fulfill one-compartment damage stability by rebuilding
a forward interior bulkhead to a
watertight bulkhead. Here, SSPA
assisted with stability evaluations,
strength calculations for the bulkhead and detailed design suggestions to meet the requirements. The
scope also included investigation
of the current physical condition
of the bulkhead and surrounding
hull structure on each vessel. SSPA
also supported FMV with all quality
inspections at the yards during the
building period as well as all delivery inspections.
A second part of the project
arose as a result of the initial work.
During the hull structure inspections, an earlier problem with
occasional leakages in the fore ship
on two vessels was addressed. After
removing the forward interior, an
inspection of the hulls revealed failures of several structural elements.
These failures resulted in cracks
in the hull plating, which caused
the leakages. Further inspections
showed that the problem was common for all vessels, i.e. this was not
an isolated case. SSPA was assigned
to investigate the reason for the failures and suggest how to repair and
strengthen the structure in order to
meet the requirements related to
the new operational area and the
planned remaining lifetime of the
vessels.
The investigation was based on
analysis of the loads on individual
structural members and on direct
calculations of the hull strength
and comparison to DNV regulations. The results showed two main
reasons for the failure. The current
operational profile resulted in higher
loads than originally dimensioned
for. The original structural design
contained some unfortunate weak
points.
In cooperation with the Shipyard
Ö-varvet (responsible for conducting the repair work on the first
vessels), new detailed designs for
repairing and strengthening the
structure were produced (the picture shows reinforced web frames).
As in the first part of the project,
SSPA then performed the continuous quality inspections and delivery
inspections at the yards. A total of
11 vessels were upgraded at four
different yards.
Niclas Dahlström
Symposium on Cavitation
(CAV2012), Singapore, 2012
Li, D.-Q., Leer-Andersen, M.,
Allenström, B.: Vortex formation of ”Flettner rotors”
at high Reynolds numbers,
29th Symposium on Naval
Hydrodynamics, Gothenburg,
2012
Kim, K., Leer-Andersen, M.,
Werner, S., Orych, M., Choi, Y.:
“Hydrodynamic Optimization
of Pre-swirl Stator by CFD and
Model Testing”, 29th Symposium
on Naval Hydrodynamics,
Gothenburg, 2012
Shiri, A., Bensow, R., Leer-Andersen, M.,
Norrby, J.: “Study of Air Cavity
Hydrodynamics for Displacement
Ships”, 29th Symposium
on Naval Hydrodynamics,
Gothenburg, 2012
Ran, H., Rask, I., Janson, C.-E.,:
“Damaged Ro-Pax Vessel Time
to Capesiz”, 11th International
Conference on Stability of Ships
and Ocean Vehicles (STAB
2012), Athens, 2012
Bengtsson, S., Andersson, K., Ellis, J.,
Haraldsson, L., Ramne, B.,
Stefenson, P.: “Criteria for Future
Marine Fuels”. Proceedings of
the International Association of
Maritime Economists (IAME)
2012 Conference, Taipei, Taiwan,
2012
Please visit
our website
www.sspa.se
www
Papers 2012
Claudepierre, M., Klanac, A.,
Allenström, B.: “ULYSSES –
the ultra slow ship of the
future”, Green Ship Technology,
Copenhagen, 2012
Li, D.-Q., Grekula, M., Lindell, P.,
Hallander, J.: “Prediction of
cavitation for the INSEAN
propeller E779A operating in
uniform flow and non-uniform
wakes”, Proceedings of the
8th International Symposium
on Cavitation (CAV2012),
Singapore, 2012
Hallander, J., Li, D.-Q., Allenström, B.,
Valdenazzi, F. Barras, C.:
“Predicting underwater radiated
noise due to a cavitating propeller in a ship wake”, Proceedings
of the 8th International
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