Technical Papers

18 - 27th HISWA Symposium 2022 - Towards Zero

The paper examines the possible options for developing specific liquid green hydrogen infrastructure to support a 100% hydrogen powered yacht. The consideration of liquid hydrogen as an alternative fuel is driven by explorative design studies exploring the feasibility of liquid hydrogen as an option for zero-carbon superyachts. The current availability of hydrogen is discussed and the challenges of providing green liquid hydrogen to a superyacht within the current industry are explored. The study investigates the proposition of superyacht industry stakeholder developing dedicated hydrogen production and bunkering facilities independent to developments in the wider marine industry. The practical and economic impact of this approach is analysed and the importance of coordination between onboard and shore-based requirements is highlighted. The paper outlines a solution with a CAPEX of between 60 and 82 million USD with OPEX values of between 4-8 million USD per year. The paper concludes that the best way to minimise these values is by a coordinated approach with other parties to increase plant utilisation and scale.

17 - 27th HISWA Symposium 2022 - Bridging the Energy Transition

The paper examines the requirements for superyacht design to adapt during the energy transition period. The driving factors for the use of alternative fuel and the need to exceed regulatory requirements and target zero emissions are discussed. The key factors for the selection of alternative fuels are considered as energy density, well-to-wake (WTW) emissions and safety.

A comprehensive range of fuels are assessed for feasibility and desirability against these factors. Three groups of fuel are identified as feasible, diesel drop-in fuels, methanol, and liquid hydrogen. The detailed ship design considerations for these fuels are discussed with examples from Lateral ship design projects.

The diesel drop-in yacht does not require any design changes, it is however most susceptible to unexpected developments or the effects of bio-mass sustainability. The methanol-fuelled yacht offers a high level of flexibility, and the option to adopt a gradual, reduced-risk approach. It requires some additional ship volume but doesn’t challenge the current yacht design convention. The liquid hydrogen yacht requires an uncompromising approach to the technical design of a superyacht and the highest risk. It is not constricted by concerns for fuel sustainability or carbon neutral accounting.

Technical papers have been the seeding ground for exploring ideas in technical depth and importantly, bringing the results into a cohesive conclusion. Often delivering complex conclusions, these have then served as the foundation for development of market facing editorial based on insights derived.

16 - RINA 2019 - The LIFE platform - Leveraging a Virtuous Circle Design

The end of 2018 saw the delivery of the motor yacht Bravo Eugenia. She is built by Oceanco based on the LIFE platform developed in collaboration with Lateral Naval Architects. This study defines the LIFE platform (i.e. Long, Innovative, Fuel efficient, Eco conscious) its key features and outlines its fundamental design pillars. The relative merits of main parameters are assessed against a typical similar sized yacht by use of baseline fleet data. LIFE’s low weight in relation to length and reduced powering requirements combined with a hybrid propulsion system result in a virtuous circle at which the centre is the single tier engine room. The benefits of the single tier layout such as the higher flexibility in designing the accommodation spaces and the improved balance between technical and luxury areas are outlined. In this context, various designers’ LIFE platform interpretations are provided as examples for discussion. The LIFE hybrid propulsion system is presented and the various modes of operations for which the hybrid system is conceived are discussed.

15 - 24th HISWA Symposium 2016 - The IMO Polar Code Large Yachts

In the interest of safety for ships and the people on board them, together with the environmental preservation of the polar waters, the International Maritime Organization (IMO) have adopted the International Code for Ships Operating in Polar Waters (Polar Code). The Polar Code will be applicable through the International Convention for the Safety of Life at Sea (SOLAS) and the International Convention for the Prevention of Pollution from Ships (MARPOL). It is expected that yacht owners and charters will become increasingly interested in polar tourism. Consequently this paper looks into the application and impact of the Code on large yacht design.

The paper summarises the various Polar Code Certifications available and highlights some aspects that could be difficult for a yacht to comply with or would have a significant impact on the design. Without understanding the ice environment that a vessel is expected to navigate in it is difficult to know how much of the Code is relevant when considering the design and naval architecture of a yacht. This paper aims to bring clarity to that based on the expected requirements of a typical superyacht owner/charterer. Through this work a recommendation for the appropriate Polar Ship Certificate and relevant regulations is made, and an assessment of the technical impact of these regulations on large yacht design has been carried out. The paper will offer naval architects and designers insight to ensure compliance with the Code and the necessary considerations for a polar yacht.

14 - 23rd HISWA Symposium 2014 - Dynamic Positioning Capabilities for Superyachts

Dynamic Positioning (DP) systems are a mature and well proven technology. The Superyacht industry has embraced DP as a concept and many large yachts now feature some level of station-keeping capability. However as DP is not widely understood beyond the basic principles, capabilities are frequently over specified and the resulting impact on the level of installed power is often severe or at odds with the propulsion system specified for the yacht.

This paper provides background to the principles of basic station-keeping, typical thruster arrangements, and how DP is used in practice. Various fundamental methods of controlling the degree of DP capability are discussed, along with the impact on the vessels’ design of implementation. A case study is used to explore a range of power generation and propulsion systems each with specific attention to the impacts on the primary design variables for large yachts.

Suggested levels of station-keeping / DP capability suitable for application to large yachts are explored allowing a better informed system specification to be made.

13 - 23rd HISWA Symposium 2014 - Advanced Propulsion Trains for Superyachts

The paper examines the benefits of advanced propulsion trains for the specific demands of large superyachts with specific focus on hybrid systems utilising a combination of both diesel-electric and diesel-mechanical propulsion.

The technical characteristics of a hybrid system are compared to diesel-mechanical and diesel-electric systems. For a basis yacht of 110m a study of predicted fuel consumption is undertaken against a number of load profiles for each propulsion system. This indicates a potential of 10% saving in annual fuel use for a typical operating profile. Fuel savings are considered against the additional high investment costs of a hybrid system which indicate that hybrid would be a long term investment.

The effects of each propulsion systems on the yachts layout are discussed and the ability to allow increased luxury interior volume by careful optimisation of the required technical space is demonstrated for the hybrid system.

Whilst the conclusions demonstrate that the hybrid system will offer technical advantages and allow an improved layout the choice of the optimum propulsion system for a given yacht will be dependent upon the individual characteristics of the yachts design and the intended operating profile.

12 - RINA 2013 - Platform Engineering for Production and Semi-custom Yachts

With the growth in the superyacht market over the last 2 decades many production boat builders, traditionally focused on yachts of less than 24m, have incrementally increased the size of their product in order to enter this market. Production boat building relies heavily on economies of scale and standardisation of design and engineering in order to reduce costs. However, to differentiate in the superyacht market calls for a degree of customisation in every boat; the bigger the boat the more customisation is expected by the client. Such customisation is at odds with production building leading to increased design, development and production costs. The use of a semi-custom model answers some of these issues and many of the established superyacht builders focused in the 30-40m range use such techniques. However utilising a model based on Platform Engineering can offer higher degrees of flexibility for both the shipyard and client.

11 - 22nd HISWA Symposium 2012 - The New Generation of Passenger Superyachts

November 2010 saw the introduction of the new passenger yacht code (PYC) which aims to provide a SOLAS equivalent code for yachts wishing to carry up to 36 passengers. Prior to this code, yachts wishing to carry more than 12 passengers were subject to full SOLAS and Loadline compliance. This paper investigates some of the differences in philosophy between the two compliance options and the impact they may have on large yacht design.

Where in the past international conventions have been considered unreasonable or disproportionately onerous for yachts, the PYC applies substantial equivalence to provide additional flexibility to the Naval Architect and Designers. This paper looks at some of these areas to assess the alternative design considerations that must be made or the benefits that can be achieved when applying the substantial equivalence of the PYC. Some of the topics discussed include lifeboats and lifesaving appliances (LSA), windows, doors, fire protection and interior build and construction materials.

In many matters relating to substantial equivalence the PYC calls for enhancement to damaged stability. Since 2009, under SOLAS, all passenger yachts are required to meet probabilistic damaged stability requirements. Under the PYC some categories of yacht are also required to meet an ‘enhanced survivability’ standard based on a 2 compartment deterministic approach. This paper also investigates the additional PYC damaged stability criteria and the impact this can have on the subdivision and arrangement of a large yacht.

10 - RINA 2011 - Reducing the Environmental Impact of Large Yachts

Over recent decades the global yachting community has become increasingly concerned with its influence on the environment. Considering the size and energy use of a large yacht it is clear that their impact can be significant. This paper looks at two mechanisms through which yachts can reduce their environmental footprint; compliance with regulation, and optimisation of design.

Progress on environmental regulation at the IMO has seen recent amendments to MARPOL and the introduction of the Ballast Water Convention. The paper will examine MARPOL exhaust emissions, MARPOL fuel tank protection and BWM requirements and qualify the impact that these environmentally targeted regulations will have on large yacht design practices and vessel arrangements.

The operating profile of a modern yacht dictates that auxiliary systems far outweigh the propulsion system in terms of contribution to the operational environmental footprint. The paper will illustrate how ancillary systems can be optimised in order to reduce auxiliary loads and therefore overall environmental impact of the vessel.

09 - 21st HISWA Symposium 2010 - Recent Regulatory Changes and their Impact on the Design of Large Yachts

The Large Commercial Yacht Code (LY2) has in the last decade become the de facto standard for the design and construction of large yachts. However the code is limited to a passenger number of 12 and a gross tonnage of 3000 GRT, implying a maximum length of approximately 85m LOA. In recent years, the number of large motor yachts outside of these boundaries has been steadily increasing making them subject to full SOLAS passenger ship regulations in addition to other pertinent conventions. This SOLAS based regulatory frame work has recently been subject to a period of significant change with the entry into force of a number of new regulations and conventions. It was recognised that gaining quantified insight into the impact of these on large yacht design would be of value to the industry, allowing refinement of design methods and procedures.

This paper investigates several new or recently updated regulations and conventions all of which will have varying degrees of impact on large yacht design practices and arrangements. These include SOLAS harmonised probabilistic stability, MARPOL fuel tank protection, MARPOL exhaust emissions, the Maritime Labour Convention and the Ballast Water Convention.

Each topic has been assessed in order to extract and summarise the relevant areas with regard to large yachts. Where possible the paper quantifies the effect the new regulations will have on yachts offering naval architects and designers insight as to how current design practices will need to change to ensure compliance.

08 - 21st HISWA Symposium 2010 - Longitudinal vs Transverse Framed Structures for Large Displacement Motor Yachts

The selection of a structural framing system in any vessel must be made from a consideration of weight, production matters, suitability to resist global loads and vibration. Vessels can principally be either transversely or longitudinally framed although hybrid systems are also in use. However the choice of which framing system is best can be the cause of considerable debate between designers and builders with the advantages and disadvantages of each system often being debated but rarely quantified.

This paper explores the structural design of an 80m displacement motor yacht utilising both transversely and longitudinally framed systems, with the aim of quantifying the weight, structural benefits, and production differences between the two. In the development of the basic structural design, rule minimum local scantlings are considered and then suitably increased to account for practical constraints, production aspects and global loads.

Following analysis of the results the Authors have assessed a hybrid framing system which is considered to combine most of the advantages of other systems.

07 - RINA 2009 - The Shaow Yacht Toy Box of the Sea

In recent years a number of yacht owners have opted for a ‘shadow yacht’ in order to carry their extensive range of ‘toys’, and free-up valuable space on board their yacht.

This paper will start by discussing the main benefits of a new-build shadow yacht, and will go on to discuss trends in superyacht size. Recommendations will also be provided on whether an owner seeking a new-build yacht may be able to reap the benefits of a new-build shadow yacht for little or no additional cost. Various design considerations and two potential design solutions for bespoke shadow yachts are presented towards the end of the paper.

06 - RINA 2007 - Project Gemini Design and Engineering of the Worlds Largest Sailing Catamaran

The 45m project Gemini, currently under construction in the USA, will be the world’s largest sailing catamaran when launched. Catamaran yachts of this size are uncommon with monohulls dominating the market. The structural design and engineering of this large aluminium catamaran has pushed the boundaries of current classification society rules. The designers have worked closely with the vessel’s classification society during the development of a new set of rules for the structural design of vessels of this type and size. An overview of the project background and decisions that led to a catamaran being selected are discussed together with a technical comparison of the proposed design with an existing monohull of comparable length. The naval architecture of this large catamaran is also discussed together with the structural analysis, design and production engineering challenges.

05 - 19th HISWA Symposium 2006 - The Modern Superyacht Enlarged Yacht of Small Ship

The increasing size of the modern superyacht is pushing the boundaries of traditional yacht architecture. Large yachts are now more akin to small ships and the naval architecture, engineering and procurement of such vessels demands an increasingly rigorous approach. Coupled with ever increasing requirements for increased range, reduced noise levels and good seakeeping ability the engineering of these vessels requires a multi-disciplined approach with increasingly higher level technical input essential from the early conceptual design stage. Within this paper the Author will examine a number of areas where mature technology developed within the commercial shipping industry is now being adopted in the yacht market and where some requirements specific to the large motor yachts are leading to adaptation of existing technology.

04 - RINA 2004 - A Technical Comparison between Monohull and Pentamaran Platforms for High Speed Operation of Future Naval Warships

The need for future warships to operate at high speeds is currently being debated around the world. The tactical advantages that can be offered by a vessel with a high-speed capability are being balanced against concerns that such craft may be technically challenging and expensive. This paper describes a technical comparison between two theoretical frigate sized vessels based on monohull and Pentamaran forms. Computational techniques and model data have been used to make an assessment of the relative merits of the two hull forms with regard to powering and seakeeping in addition to stability, maneuverability, space and cost. The capital and fuel costs are illustrated for both vessels and it is shown that having a high-speed capability does not impose significant fuel cost increase.

03 - FAST 2003 - Minimising The Effects of Transom Geometry on Waterjet Propelled Craft

The use of waterjets in vessels operating in the displacement and pre-planing regimes can lead to restrictions in transom geometry that impose significant drag penalties. The degree of freedom to which the designer has room to optimise the stern design of such vessels is restricted by the geometrical constraints of the propulsor fit. The design development of two specific examples are given; the first being a large high speed containership and the second a high speed patrol boat. The development of a novel, ‘gullied’ stern design and its application to both of these vessels is described in the paper together with drag predictions in support of its merit in reducing the drag of waterjet propelled craft operating in the preplaning regime.

02 - FAST 2003 - The Effects of Length on the Powering of Large Slender Hull Forms

For a constant deadweight, increasing ship length is generally desirable to reduce total resistance and installed power. For large vessels where global loads dominate structural design the weight growth with length increases can be significant. Previous design studies of large slender Ro-Pax and containerships have indicated that the level of this weight increase can be of sufficient magnitude to negate any performance benefit derived from the increased ship length. As the structural weight for these types of vessels can represent 65% of the lightship weight, accurate conceptual design stage weight estimation is critical to both comparative studies between candidate designs and progression through the design cycle.

The results of a parametric study of a 6000t dwt, 40knot Pentamaran Ro-Pax are presented. The main aim of this study has been to investigate the optimum ship length to minimise the installed power demand. Conceptual design methods have been developed for assessing the impact of length driven increases in longitudinal bending moments on structural weight.

01 - RINA 2002 - High Speed Craft Technology - Ocean Transits in a 50m, 45 knots Catamaran The Minimisation of Motions and Speed Loss

This paper describes the design and tank testing of a new fast catamaran vessel designed for the United States Navy Office of Naval Research for use as a Littoral Surface Craft designated LSC(X). A two year development programme at NGA produced a new hull form, the Modcat, which when coupled with a powerful ride control system met all of the US Navy Office of Naval Research requirements. Initial numerical studies predicted very low motions and speed loss. To validate the prediction an extensive programme of tank tests was undertaken in the ocean basin at Marintek, Trondheim.