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Worldwide ship accidents (1995-1999) due to severe weather. Source: Lloyd’s Marine Information Service (LMIS) casualty database.
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Description of freak waves is not only important for design work but also for operational purposes it would be of benefit if warnings could be given to mariners. Meteo-centers already provide wave forecast based on spectral wave model. Although a spectrum gives some average description of the sea-state, it might contain additional information indic...
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... years (1995 -1999) of ship accidents due to bad weather, collected from the Lloyd's Marine Information Service (LMIS) and Lloyd's casualty reports have been studied. The location of ship damages as well as losses due to severe weather are shown in figure 1. Although only a few accidents are categorized as being caused by freak waves (e.g. ...
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... The ship accident data due to bad weather from the Lloyd's marine information services shows that the north Indian Ocean (comprises of Arabian Sea(AS) and Bay of Bengal (BOB)) is a ship accident prone area (Toffoli et al., 2003). The ship data base developed by using satellite data shows that the ship density in the north Indian Ocean is on the higher side (Jean, 2015). ...
Unexpected occurrences of freak waves endanger safe navigation and operational activities in the ocean. To reduce the potential marine accidents, many oceanographers have investigated the probability and mechanism of freak wave occurrences and discussed some relevant environmental factors leading to freak wave generations. However, study on the occurrence of freak waves in the Indian Ocean is very limited. In this study, the existence of freak waves is shown in the north Indian Ocean using observed moored buoy data. Fifty five freak wave events are reported by analyzing available buoy data from the year 2009–2017. All of the events occurred in a combined sea state of swell and wind sea. This study further provides a detailed analysis of the met-ocean conditions, which took place during some selected incidents of the freak wave in the north Indian Ocean. The commonly observed factors during the freak wave events in the north Indian Ocean are cross sea condition, increase in wind speed, rapid development in the sea state and steepness is greater than 0.01. Our analysis supports the fact that swell and wind sea make a coupled system during freak wave events.
... Many ship accidents, from damage to disappearances, have been reported that were likely related to rogue waves [5]; although most of these were not described as such, but rather it was inferred from accounts. The recognition of the hazards that are associated with extreme waves has increased in recent years, mainly due to incidents of waves striking passenger ships and platforms (e.g., the Draupner in 1995, the Queen Elisabeth II in 1995, the Caledonia Star and Bremen in 2000, the Explorer, Voyager and Norwegian Dawn in 2005, the Louis Majesty in 2010 and the MS Marco Polo in 2014), some of which resulted in fatalities [6][7][8]. The Draupner wave in 1995 was the first rogue wave to be recorded by sensors at a gas platform in the North Sea. ...
Rogue waves are a recognized but not fully comprehended hazard of major concern to the maritime industry. There is not one agreed-upon unified model that explains the formation of such waves and little is known about their frequency of occurrence. This study used in situ data from a wave buoy located at the entrance of Tampa Bay, Florida, to assess conditions that could lead to the development of these potentially destructive waves. Tampa Bay is a major commercial and transportation hub on the east coast of the United States. Wave buoy data from 2015 to 2019 were analyzed in this study. While more than 7000 individual waves that significantly exceeded median values were recorded, only 32 exceeded 4 m, thereby imposing risks to local navigation. The largest rogue wave that was recorded was 8.46 m high. Parameters in the time and frequency domains were calculated, local wind and surface current data were correlated, satellite synthetic-aperture radar (SAR) and vessel traffic data were analyzed, and the local bathymetry was considered. Based on our results, the narrow directional wave spreading that was found on the selected rogue waves was recognized as an important indicator of extreme waves. The parameters: surface elevation kurtosis, Benjamin-Feir Index (BFI), wave steepness, broadness, and narrowness factors, wind speed and direction, can be considered together, as a part of a local extreme-wave warning package. The selected individual rogue waves could not be identified using SAR imagery. Regional disturbances from ship wakes were analyzed but yielded no connections to the local formation of rogue waves.
... Each EF and CP may change continuously during any navigation period. When the CP related to all EFs is no less than that determined based on historical SCA data, the SCA probability related to the navigation environment may be regarded as the warning value (Toffoli, 2003). ...
... and the CP is very low. This suggests that the CP is independent of any change in the ship density except for that while SDS is close to 0.6 (the corresponding ship density: [15][16][17][18][19][20]. If the number of SCAs corresponding to the ship density (< 5 or > 30) rises, a higher ship density leads to an increase in the CP (Figure 7). ...
The ship collision accident (SCA) risk for any ship approaching any other change from the causation probability (CP) to the geometric probability (GP) in regime. Because ship operators may not be aware of the environmental factors (EFs) related potential risks in high CP during the initial stage of the GP analysis process, it is likely that higher-grade SCA measures will not be taken. However, if any EF-related CP is told to ship operators, they can take more effective and intentional measures in time; moreover, if the CP corresponding to navigation-related EFs is no less than the risk early warning critical value (REWCV) calculated based on historical SCA data, SCAs will be in a high-risk level. A new method was put forward here based on a quantitative analysis of EFs and previous SCA statistics to provide early warning of any SCA risk; and then a REWCV can be obtained based on quantified EFs by applying such method which is relatively simple but high operational and practical. A case study of Three Gorges Reservoir in China indicates that the range of EF values for which the probability of a SCA grows rapidly is consistent with environmental limits defined by Chinese maritime standards. Moreover, the modified critical value of the EF-related CP shall be further refined to act as the REWCV for CAs. In addition, the relationship (REWCV vs. the number of previous SCAs) was clarified.
... The Cook Inlet, has a tidal range of 8-9 m, forcing currents about 1-2ms −1 during full tidal flow, and currents are generated by wind and baroclinic forcing (Singhal et al., 2013). Wave height and steepness could increase due to a strong opposing current (Kharif and Pelinovsky, 2003;Onorato et al., 2011;Toffoli et al., 2003) by altering the dispersion relation and spatially focus wave energy, forming rogue waves (Heller et al., 2008;Lavrenov , 1998;Peregrine, 1976). ...
Rogue waves are ocean surface waves larger than the surrounding sea that can pose a danger to ships and offshore structures. Fatal accidents are not just as a result of the wave size but the unexpected nature of the event. Despite rogue wave prediction being sought for decades, all current prediction methods are not operationally viable as they require complex measurement of the wave field and computationally intensive calculation, which is infeasible in most applications. Consequently there is a need for fast predictors.
Here we collate, quality control, and analyse the largest dataset of single-point field measurements from surface following wave buoys to search for predictors of rogue wave occurrence. We find that analysis of the sea state parameters in bulk yields no clear predictors, except spectral bandwidth parameters which display different probability distributions in rogue seas to normal seas, but these parameters are rarely provided in wave forecasts. When location is accounted for, trends can be identified in the occurrence of rogue waves as a function of the average sea state characteristics at that location. We find that frequency of occurrence of rogue waves and their generating mechanism is not spatially uniform, and each location is likely to have its own unique sensitivities which increase in the coastal seas. Further, we investigate the temporal variability rogue waves along the US western seaboard, to investigate regional trends in significant wave height and individual rogue waves. We find high spatial variability in trends in significant wave height and rogue waves across the region. Rogue wave occurrence displays a mostly decreasing trend, but the relative height – or severity – of the waves is increasing. We also identify seasonal intensification in rogue waves with increased rogue wave occurrence, of higher severity, in the winter than in the summer. Finally we investigate the feasibility of rogue wave prediction using existing technologies by applying our learnings to machine learning algorithms to build a predictive model based on the short-term sea state statistics that are forecast by wave models. We find that the rarity and complexity of the phenomenon leads to an imbalanced and overlapping dataset and consequently poor classification ability by machine learning models. The performance is deemed too low to be of practical use to the mariner at this time.
... Akten (2004) identified that natural conditions such as current, tide, severe wind, reduced visibility, stormy seas can affect the safe operation of a ship thus leading to a marine accident. Toffoli et al. (2003) argues that even with good and accurate forecasts that marine accidents still happen from unrelenting harsh weather conditions or even from less severe circumstances. He stated that this has prompted various metro-centres to incoperate the sea state in marine weather forecast when it surpasses a certain threshold. ...
ABSTRACT
The continuous growth of the maritime sector in Nigeria, indicate an increase in shipping activities and tonnage. The prosperity of the sector helps in boosting the National economy. But then the occurrences of marine accidents and its implications tend to pull back this progression every now and then.
The results of the marine accidents that occur on the inland and coastal waters of Nigeria affects the economy in such a way that it broods economic loss and impacts the finances of the shipping companies involved, who tend to pay out a lot of money subsequent to these marine accidents.
This paper aims at discussing the impacts these accidents have on the economy by way of damages to natural resources through pollution; then loss of lives and creation of wrecks litters. Secondly, it accesses the cost of marine accidents and the extent of monetary pay out by companies involved in the accidents. This assessment will be done through the secondary data as well as primary data gotten from shipping companies by way of responses to the questionnaire used.
However, these frequent marine accidents resulting to economic losses tend to point that there is a gap in the implementation and execution of the safety regulations, since Nigeria is signatory to many safety regulations and conventions.
... The satellite images of the 100 Â 100 km area around Draupner during the January 1 storm in 1995 showed two peaks in the directional spectra, indicating that crossing seas were generating extreme waves (Rosenthal and Lehner, 2008). As a result of MaxWave, Meteo France now uses a Cross Sea Index that uses crossing wave trains as a daily warning criterion of extreme wave conditions in the Mediterranean (Toffoli et al., 2003). A similar effect occurs at coastlines where reflected waves may constructively interact with incident waves to produce abnormally high waves, which may then cause beach and dune erosion, overtopping, and flooding as occurred along the coast of Northeast Scotland in the exceptional storms of December 2012 (Figure 11.2). 2. Current focusing occurs where waves traverse an area of variable currents and, acting like an optical lens, the currents focus wave action into a caustic region to produce freak, rogue, or giant waves ( Figure 11.3) (White and Fornberg, 1998). ...
The existence of extreme waves, as observed by seafarers, has been confirmed by data recording and modeling to be more common than previously assumed. Extreme waves mainly occur during major storms at sea by means of constructive interference of wave trains or by nonlinear wave interaction, but extreme waves may also be associated with tsunami or meteotsunami events. If they arrive at the coast, most extreme waves have the potential to cause extensive remodeling and repositioning of the shoreline environment and landforms as well as causing significant damage to human infrastructure and threat to life. The impact of extreme waves on both sedimentary and rocky coasts can be substantial with sediments or rocky boulders eroded from the coastal edge being transported and deposited some distance inland. This characteristic provides clues to the nature of the extreme event and, if recorded within the recent sedimentary record, information about the periodicity of similar events. The impact of extreme waves on coastal communities and environment has prompted a range of mitigation and adaptation strategies to cope with these hazards. These include more robust coast defences, better modeling, prediction and warning systems, improved interagency liaison, improved technical assistance, and storm impact management information for the general public, as well as provision of clear evacuation routes during a wave-related emergency. However, since climate change seems likely to result in increased rates of both sea-level rise and storm-related impacts, there is an emerging consensus that adaptive management of the coastal zone may prove to be a more sustainable strategy than the alternatives.
... The satellite images of the 100 Â 100 km area around Draupner during the January 1 storm in 1995 showed two peaks in the directional spectra, indicating that crossing seas were generating extreme waves (Rosenthal and Lehner, 2008). As a result of MaxWave, Meteo France now uses a Cross Sea Index that uses crossing wave trains as a daily warning criterion of extreme wave conditions in the Mediterranean (Toffoli et al., 2003). A similar effect occurs at coastlines where reflected waves may constructively interact with incident waves to produce abnormally high waves, which may then cause beach and dune erosion, overtopping, and flooding as occurred along the coast of Northeast Scotland in the exceptional storms of December 2012 (Figure 11.2). 2. Current focusing occurs where waves traverse an area of variable currents and, acting like an optical lens, the currents focus wave action into a caustic region to produce freak, rogue, or giant waves ( Figure 11.3) (White and Fornberg, 1998). ...
The existence of extreme waves, as observed by seafarers, has been confirmed by data recording and modelling to be more common than previously assumed. Extreme waves mainly occur during major storms at sea by means of constructive interference of wave trains or by non-linear wave interaction but extreme waves may also be associated with tsunami or meteotsunami events. If they arrive at the coast, most extreme waves have the potential to cause extensive remodelling and repositioning of the shoreline environment and landforms as well as causing significant damage to human infrastructure and threat to life. The impact of extreme waves on both sedimentary and rocky coasts can be substantial with sediments or rocky boulders eroded from the coastal edge being transported and deposited some distance inland. This characteristic provides clues to the nature of the extreme event and, if recorded within the recent sedimentary record, information about the periodicity of similar events. The impact of extreme waves on coastal communities and environment has prompted a range of mitigation and adaptation strategies to cope with these hazards. These include more robust coast defences, better modelling, prediction and warning systems, improved inter-agency liaison, improved technical assistance and storm impact management information for the general public, as well as provision of clear evacuation routes during a wave-related emergency. However, since climate change seems likely to result in increased rates of both sea level rise and storm-related impacts, there is an emerging consensus that adaptive management of the coastal zone may prove to be a more sustainable strategy than the alternatives.
... Some recent studies (Guedes Soares et al., 2001; Bitner-Gregersen and Guedes Soares, 2007) have shown that most of the marine accidents induced due to severe weather conditions occurred in areas with the highest significant wave height or with wave steepness greater than average. The general statistics show that about 23% of the ships accidents are caused by the sea state and weather conditions, the latter being in fact the second most common cause for such events (Toffoli et al., 2003). Toffoli et al. (2003) also showed that the responses of the vessels at a certain sea state depend on the type and the size of vessel. ...
... d due to severe weather conditions occurred in areas with the highest significant wave height or with wave steepness greater than average. The general statistics show that about 23% of the ships accidents are caused by the sea state and weather conditions, the latter being in fact the second most common cause for such events (Toffoli et al., 2003). Toffoli et al. (2003) also showed that the responses of the vessels at a certain sea state depend on the type and the size of vessel. It was noticed that the ships are vulnerable mainly to the wave lengths greater than half of the ship length and only few accidents occurred at wave lengths less than half of the ship length. On the other hand, different types ...
This work presents a methodology for the evaluation of the vessels operability in the basin of the Black
Sea. The approach proposed is based on the results provided by a wave prediction system that was
implemented and validated in the Black Sea. This offers a meaningful framework in the assessment of
the seakeeping performance for ships operating in different conditions. The aim of the work is to
improve the seakeeping performances for various types of ships that sail in the Romanian coastal
zones. Two containerships are considered, of 1300TEU and 800TEU respectively, which have
however the same displacement. For predicting the ship motions induced by the various wave
conditions encountered in the operational area, it is necessary to know the transfer functions for
different ship speeds and heading angles. These are computed with a numerical code based on the
strip theory. The predicted motions are then compared with the limit values of the relevant seakeeping
criteria, considered as the criteria for checking the operability of the ship. By defining the acceptable
operating boundaries, the ship behavior in waves can be quantified. The vessel meets the criteria for
those combinations wave height-wave period that are below the limit curves. The results are presented
as operational maps for the Black Sea basin, allowing the identification of the areas that should be
avoided due to unfavorable weather conditions. The methodology proposed herewith can be extended
and applied to various marine environments and types of ships.
... During incidents, it is therefore expected that relatively high values will be recorded. Toffoli et al. [22] found, however, that rather low significant wave heights occurred during those ship accidents, which have been reported as being due to bad weather. Note that [22] used the global wave analysis sets of the ECMWF operational wave model. ...
... Toffoli et al. [22] found, however, that rather low significant wave heights occurred during those ship accidents, which have been reported as being due to bad weather. Note that [22] used the global wave analysis sets of the ECMWF operational wave model. About 80% of those incidents took place within January 1995 to June 1998, when the model was run with a spatial resolution of 1.5 • . ...
... Toffoli et al. [22] suggested that an interpretation of wave forecasts should be given for each type of ship and for each individual ship, since vessel responses in a sea state depend on the ship type and ship dimensions. Due to lack of information, the ship gross tonnage represents the only parameter that can be related to the ship size. ...
A ship that founders presents a great disaster both from an economical and a human point of view. It is therefore of concern to meteorological centers to include sea state related parameters in marine weather forecasts when they exceed a certain threshold. At present a standardized warning system is not set up yet. To contribute towards the definition of adequate warning criteria, an investigation was undertaken of ship accidents reported as being due to bad weather. Sea state related parameters (i.e. meteorological centers’ standard wave products) at the time of 270 accidents were analyzed and compared to known ship characteristics. In order to estimate a certain degree of severity, results were compared to wave climate variation. In particular the use of quantiles seemed to provide a reasonable description of dangerous seas.
... Figure 5 shows an accident map based Hapag Loyds database. For details and further accident maps see Soares et al. (2001) and Toffoli and Monbaliu (2003). Wave conditions for ship design (IST) Figure 6 shows the impact on the bow of MV Wilstar, which was hit by a rogue wave in the Algulhas current. ...
... This leads to the definition by Meteo France of a new cross sea index used as a warning criterion (Toffoli et al., 2003). ...
Heavy sea states and severe weather conditions have caused the loss of more than 200 super carriers within the last 20 years. In many cases single 'rogue waves' of abnormal height as well as groups of extreme waves have been reported by crew members of such vessels. The European Project MAXWAVE deals with both theoretical aspects of extreme waves as well as new techniques to observe these waves using different remote sensing techniques. The final goal was to improve the understanding of the physical processes responsible for the generation of extreme waves and to identify geophysical conditions in which such waves are most likely to occur. New radar data were used to compile a cen- sus on wave statistics with respect to those extreme wave events and to improve prediction of such events. Several ship and offshore platform accidents are analysed and the impact on ship and offshore design is discussed.
