A seakeeping analysis method for an air-lifted vessel

A seakeeping analysis in the frequency domain is presented to predict the motion response of an airlifted vessel (ALV) in waves. The ALV is supported by pressurised air in two separate cushion chambers; the pressure variation in the cushions has a significant effect on the motions of the vessel. The adiabatic gas law is used to couple cushion pressure and the free-surface elevation of water inside the chamber. Attention is focused on the waves generated by the pressure, and a method is presented to compute the corresponding free-surface elevation. New numerical schemes are proposed for calculating the threedimensional free-surface elevation for the four wave numbers. Numerical results of the free-surface elevation, escape area, escape volume and motion responses of the ALV are provided. & 2008 Elsevier Ltd. All rights reserved

Decision support for ship flooding crisis management

Decision support systems for onboard use are many and varied. Primary role of such systems is to alleviate burden of processing of ship and environment data and ultimately to help crew in making informed decisions. Effectiveness of such processing could not be more important than during crises situations. This article presents with a prototype of an ergonomic decision support function for provision of advisory to the crew for enhancing their instantaneous preparedness for response to a distressed flooding situation. It is argued that inculcation of crew preparedness is the most effective tool for avoiding and managing flooding crises, should they occur

Impact of sulphur exploitation on geochemical features of surficial environment of sulphur deposits from Polish-Ukrainian borderland

Eksploatacja złóż siarki rodzimej prowadzi do znacznej degradacji środowiska naturalnego. Złoża siarki Basznia i Niemirów znajdujące się na północnym obrzeżu zapadliska przedkarpackiego, na pograniczu Polski i Ukrainy, eksploatowane metodą otworową, w latach 90. ubiegłego wieku zostały zamknięte. Tereny poeksploatacyjne charakteryzują się znacznym przekształceniem mechanicznym i chemicznym gleb oraz degradacją przypowierzchniowych warstw gruntu. Badania geochemiczne próbek gleby z obszaru eksploatacji wskazują na silne zakwaszenie gleby (pH zwykle 2–6) oraz podwyższoną koncentrację Ba, Ca, S i Sr na obszarze poeksploatacyjnym względem obszaru otaczającego.Native sulphur exploitation leads to strong degradation of natural environment. Sulphur deposits like Basznia and Nemyriv occurring along the northern margin of the Carpathian Foredeep in the Polish-Ukrainian borderland were exploited using method of underground melting by hot water. The exploitation was stopped in the nineties. The sulphur mine areas are characterized by strong mechanical and chemical soil transformations. Geochemical analyses of soil and subsoil material reveal that the anthropogenic changed soils are distinctly acidic (mostly pH = 2–6) and enriched Ba, Ca, S and Sr compared to adjacent forest and agriculture grounds

New insights into ship-floodwater sea dynamics

This paper aims to clarify a number of issues concerning the dynamics of a damaged ship, interpreting the results of recent towing tank tests by means of a simplified linear model with two degrees of freedom. In this sense, this work can be seen as the natural evolution of the extensive body of work in this field undertaken by the SSRC during a long series of large research projects, including the Joint North West European Project [2], the MCA funded Time Based Survival Criteria of Passenger Ro-Ro Vessels, Phase 1 and 2 [3] and, above all, the Fifth EC Framework RTD projects HARDER and NEREUS [1], during which the experimental evidence presented in this paper was collected

Time-based survival criteria for passenger ro/ro vessels

This paper outlines the study undertaken within the framework of research aiming to address the compound problem of the absolute time available for passenger evacuation on a damaged passenger/RO/RO vessel undergoing large-scale flooding of car deck spaces. Deriving from extensive experimental information and utilizing static equivalent method (SEM) principles, a methodology for predicting ship survival time is proposed that accounts for wave characteristics, water ingress/egress, and vessel survivability. The progress achieved to date is discussed, and aspects needing further investigation are highlighted

A numerical method for predicting wash waves of SES

A numerical method is presented for predicting wash waves of Surface Effect Ships (SES)at deep waters.The wash waves of the SES are represented by the wave-making of a moving rectangular pressure distribution over the air cushion. Basing on the linear potential theory, the wash waves can be analytically expressed as integrals whose integrands oscillate with high frequency.The numerical procedure involves transformation of the integral variables,such that the integrands are monotonic for different vessel speed,shape of the pressure patch and locations of the wave to be calculated,and easy to facilitate the numerical calculation.The singularities of the integral can be also removed. Numerical results show that the present method is of high computational efficiency and with good agreement with the published results. Some results of wash waves of SES are presented and discussed.The characters of local and non-local effect parts of the wash wave of SES are discussed. Attempt is also tried to apply the present method in predicting wash wave of conversional catamaran,the comparison between the prediction and the model test measurement shows fairly good agreement

A risk-based first-principles approach to assessing green seas loading on the hatch covers of bulk carriers in extreme weather conditions

This paper aims to present and explain the work undertaken at the SSRC on the Safety of Bulk Carriers in extreme weather conditions over the past 3 years, to draw conclusions deriving there from, concerning key influencing design, operational and environmental parameters and to offer recommendations regarding the rule development process and on the way forward considering research, development and implementation to ship design and operation with the view to improving the safety of these ships cost-effectively. In severe storms, hatch covers of low freeboard vessels such as bulk carriers are the first-line of protection against flooding. Present methods of hatch covers design are still empirical because impact loads due to green seas and structural behaviour due to this type of loads have not been examined, hence not known accurately. The loading due to green seas is implicitly non-linear and, as model test results demonstrated, bulk carriers in extreme conditions are exposed to significant loads, which in some cases exceed current design standards. Since the consequences of hatch cover failure are potentially catastrophic, the risk of this happening should be quantified in probabilistic terms as required by modern safety standards. To this end, the paper aims to propose and implement a methodology for estimating probabilities of deck wetness and impact loads due to green seas as a function of key design and operational parameters

Marginal facies of Badenian and Lower Sarmatian of the Fore-Carpathian Basin in SE Poland and western Ukraine – results of research during the last two decades

Przedstawiono charakterystykę litologiczną utworów mioceńskich występujących na Roztoczu i terenach sąsiednich (zachodnia Ukraina). Utwory dolnobadeńskie rozpoczynają się transgresywnymi piaskami i piaskowcami kwarcowymi; w wyższej części obocznie przechodzą w margle i wapienie litotamniowe. Powstały w płytkowodnym, wysokoenergetycznym morskim środowisku sedymentacji, o zmieniającym się w czasie chemizmie wód. Środkowobadeński gips pierwotny tworzy szeroką brzeżną platformę siarczanową; w trakcie jego depozycji następowały znaczne wahania składu chemicznego solanek. W płytszych częściach zbiornika na gipsach występują utwory wapienia ratyńskiego, związane genetycznie z transgresją morską. W późnym badenie obszar Roztocza był strefą tranzytową dla materiału bioklastycznego i terygenicznego, w jej obrębie odbywało się przemieszczanie materiału ziarnowego związane z falowaniem i prądami wywołanymi przez falowanie oraz z ruchami masowymi. Węglany dolnosarmackie Roztocza cechują się nietypowym wykształceniem facjalnym oraz ubogim składem taksonomicznym organizmów, wskazującym na anomalne warunki środowiskowe – obniżone zasolenie wody i silne jej przesycenie względem węglanu wapnia.Lithological characteristics of Middle Miocene strata of the Roztocze region (SE Poland and western Ukraine) is summarized. The Lower Badenian sequence begins with transgressive quartz sands and sandstones that subsequently are passing laterally into marls and coralline algal limestones. They originated in shallow-water, high-energy marine environment. The chemistry of waters at that time as well as during subsequent gypsum sedimentation fluctuated quite considerably. Middle Badenian gypsum deposits build a wide marginal sulphate platform. In shallower parts of the basin the Ratyn Limestone deposits cover gypsum; they are related genetically to new marine transgression. During the Late Badenian the Roztocze region was a transit zone for bioclastic and terrigenous material, and the grainy material was transported owing to waves and wave-generated currents as well as mass movements. The Lower Sarmatian carbonates of Roztocze show a typical facies and poor taxonomic composition of fossil assemblages that indicate abnormal environmental conditions – decreased water salinity and its oversaturation in respect to calcium carbonate

Miodobory – środkowomioceński system rafowy, jego zróżnicowanie biologiczne i litofacje

The unique Middle Miocene reef belt formed within the Paratethyan realm constitutes at present the Medobory Hills in western Ukraine and northernmost Moldova. Not only is the size of this structure (almost 300 km long) quite unusual, but also the development of peculiar facies and their spatial distribution. Two distinct reef generations appear in Medobory (Late Badenian and Early Sarmatian), both separated by a sharp erosional boundary. Two Upper Badenian calcareous lithofacies dominate – organodetrital and biohermal (with coralline-algae as main framework builders accompanied by a rich invertebrate assemblage). The Lower Sarmatian strata, although megascopically very similar to Upper Badenian ones, differ drastically when studied closely. The main reef components here are serpulids and microbialites, usually with ubiquitous, but taxonomically highly impoverished fauna. Differences in lithofacies and biotic communities between both reef systems unveil open-marine environment during formation of Upper Badenian reefs and a drastic change of conditions at the Badenian/Sarmatian boundary (including emersion and intense weathering). The Early Sarmatian basin was established soon after and highly restricted conditions prevailed in it (e.g. with mesohaline waters and intense evaporation occurring simultaneously); its deposits are the last record of Middle Miocene sedimentation within the Medobory area.Wzgórza Miodoborów, rozciągające się na przestrzeni niemal 300 km na obszarze zachodniej Ukrainy i północnej Mołdawii, założone są na pasie raf miocenu środkowego, uformowanych w obrębie północno-wschodnich peryferii Paratetydy. Znaczne zróżnicowanie litofacjalne, jak i zmienność zespołów biotycznych wśród utworów rafowych jest rezultatem obecności dwóch generacji raf (późnobadeńskiej i wczesnosarmackiej) oddzielonych wyraźną powierzchnią erozyjną. Wśród wapiennych osadów górnego badenu dominują litofacje organodetrytyczne i biohermalne. Ich głównym składnikiem skałotwórczym są krasnorosty, którym towarzyszą bogate taksonomicznie zespoły bezkręgowców, obejmujące m.in. korale, mięczaki, szkarłupnie. Rafy sarmatu dolnego budowane są przez mikrobiality, w obrębie których występują serpule (i podrzednie mszywioły). Silnie zubożona taksonomicznie fauna zamieszkująca rafy sarmackie zdominowana jest przez mięczaki. Różnice bio- i litofacjalne w obrębie wymienionych generacji raf są efektem drastycznej zmiany warunków sedymentacji, połączonej z emersją i intensywnym wietrzeniem, do której doszło na przełomie badenu i sarmatu w efekcie przebudowy basenu przedkarpackiego. W jej wyniku pełnomorski zbiornik późnobadeński został zastąpiony przez silnie izolowany basen wczesnego sarmatu, zaś powstałe w tym ostatnim osady wieńczą sukcesję utworów miocenu w tej części zapadliska przedkarpackiego