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Manoeuvring study – Norwegian double-ended ferry

Berg T. E., Selvik Ø, Steinsvik K., Leinebø D.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2021

Vol. 15 No. 1

63--69

The Norwegian coastline has many long fjords where crossings are necessary for transportation of goods and passengers. In the last decade, the focus on reduced travel time along the main roads in coastal areas has increased the building of bridges and subsea tunnels. However, at present and in the future many fjord crossings will depend on ferries. The Norwegian government [7] requires that ferries, like all coastal ships in Norwegian waters, should be designed for zero or low greenhouse gas (GHG) emissions to meet the national goal of 50% reduction of GHG from coastal shipping by 2030. As ferry services are regulated by national or local governmental bodies, all new ferry operations should be performed using zero- or low-emission ferries. Thus, ferry companies require new and innovative ferry designs with reduced resistance, resulting in reduced installed propulsion power. This paper describes work done by the ship designer HAV Design AS (former Havyard Design & Solutions AS (HDS)) to meet the governmental request for ferries with a low environmental footprint. Work on a double-ended ferry design is described. In the early design phase manoeuvring performance is not a priority item, partly due to lack of a simple and reliable manoeuvring performance prediction tool for unconventional ship designs. It is well known that optimization of resistance can be at the cost of manoeuvring performance. In this paper, a specific double-ended ferry design will be used as a case. Outcomes of design simulation of manoeuvring performance are compared to manoeuvring full-scale tests in deep, calm water. Full-scale test results will later be used to tune a simulation model for a future training simulator for double-ended ferry, where full-scale manoeuvring tests have been performed, will be used as a test case. This paper shows how the designer has worked with these two topics in parallel in the final design stage where both experimental and numerical tools have been used for design verification.

Selection of the most suitable method to split the resistance increment into components related to individual propellers of double-ended ferry

Jarzyna H.

Archives of Civil and Mechanical Engineering

2007

Vol. 7, no 3

143-150

The resistance increment [...] measured in model propulsion tests of a double-ended ferry with the pushing aft propeller SR and the pulling fore propeller SD is to be split into two components: [...] and [...] related to each of the propellers. The splitting procedure based on the measured magnitudes is possible only when additional assumptions are made. Two procedures are presented in this paper. The first procedure, i = l, is directly related to the components of resislance increment [...] and [...]. The second procedure, i = 2, is related lo the components [...] and [...] attributed to individual propellers. In both procedures the same assumptions are used for splitting. Proposed assumptions are based on the proportion of propeller thrust TR and TD, or on the proportion of the delivered power [...] and [...]. Procedures combined with assumptions define the methods and are denoted Kij where subscript refers to the assumption. Two prerequisites were formulated. Both have to be satisfied by methods of practical importance: Above prerequisites are satisfied only by the K11 and K21 methods. The methods KI3 and K23 satisfy only the first prerequisite.

Pomierzoną w modelowych badaniach napędowych promów symetrycznych globalną zmianę oporu kadłuba [...] wskutek działania śruby rufowej SR i dziobowej SD należy podzielić na składniki [...] i [...] związane z każdą ze śrub. Podział taki możliwy jest pod warunkiem przyjęcia dodatkowych założeń. Praca analizuje możliwe założenia w dwu grupach proceduralnych. Procedura pierwsza, i = l, wiąże bezpośrednio zmiany [...] i [...] z hipotezami zmian. Procedura druga, i = 2, wiąże zmiany [...] z tymi samymi hipotezami zmian. Hipoteza pierwsza, j=l, zakłada proporcjonalność zmian z obu procedur do mierzalnych naporów TR i TD). Hipoteza druga, j = 2, zakłada proporcjonalność zmian z obu procedur do mierzalnych mocy PDR i PDD. Rozpatruje się kryteria zmian określane jako Kij. Sformułowano dwa warunki, jakie spełniać winny poszczególne kryteria akceptowalne do stosowania. Stwierdzono, że oba warunki są spełnione, gdy stosuje się kryterium K11 i kryterium K21. Kryteria K13 i K23 spełniają jedynie warunek pierwszy.