B6371 - Vessel Design

Learning outcomes

The main objective of the course is to provide students with the tools necessary for designing innovative, technological and sustainable boats. At the end of the course, students will be able to develop a preliminary boat design. They will also be able to evaluate the main interactions between the various specialist aspects characterising the ship design and to work on the linear and iterative path of the design spiral.

Course contents

The course addresses the preliminary design process of sailing and motor pleasure craft, with particular attention to the relationship between naval architecture, functional requirements, safety, stability, performance, ergonomics and integrated design development.

The objective is to provide students with the basic tools required to understand and develop a coherent preliminary design, from the definition of the design brief to the critical presentation of the project deliverables.

1. The Yacht Designer

Role of the designer. Design culture, design ethics, sustainability and responsibility. The relationship between art and science in yacht design. The sea as a constant constraint in the design process. Evolution of digital tools and the role of artificial intelligence as a support, not a replacement, for the creative and technical design process.

2. The Client and the Design Brief

From the design brief to market analysis. Distinction between custom, semi-custom and series production projects. Interpretation of the requirements of the owner or the shipyard. Definition of the vessel mission, target use and main dimensional, functional, economic and regulatory constraints.

3. Classification and Typologies of Boats and Ships

Regulatory definitions of pleasure craft, small craft, recreational boats and pleasure yachts. Hull length according to ISO 8666 and difference between LOA, Lh and LWL/DWL. Introduction to the European Recreational Craft Directive, the Italian Pleasure Craft Code and design categories.

Classification of vessels according to size and regulatory thresholds, intended use, type of propulsion, navigation regime, hull configuration, construction method and production process.

Overview of the main boat and ship typologies: sailing and motor vessels, monohulls and multihulls, small craft and pleasure boats, cruisers, racer-cruisers, blue water cruisers, racing yachts, open boats, day cruisers, hard-tops, walkarounds, fishermen, flybridges, express cruisers, lobster boats, modern gozzi, pilot boats, trawler yachts, navettas, explorer yachts, expedition vessels, chase boats, support vessels, shadow vessels, superyachts and pleasure yachts over 24 metres.

Introduction to the main criteria guiding typological choices: vessel mission, navigation area, required comfort, range, speed, efficiency, safety, costs, materials and level of industrialisation.

4. Design Process and Design Spiral

The design spiral as an iterative process. Relationship between requirements, weights, displacement, stability, propulsion, layout, costs, schedule and regulations. Project maturity levels: concept, preliminary design, contract design, detail/construction design. Minimum deliverables, project drawings, decision log and progressive freezing of design parameters.

5. Geometry and Hydrostatics of the Sailing Yacht Hull

Main elements of the above-water hull: sheerline, stem and transom. Hull lines geometry and lines plan: sections, waterlines, buttocks, diagonals and sectional area curve. Main dimensions and parameters: length, beam, draught, freeboard, waterplane area, wetted surface, midship section, immersed volume and centre of buoyancy.

6. Use of Software for Hull Design and Preliminary Verification

Introduction to the use of software for hull design and preliminary verification, with reference to commercial tools such as Orca3D and Maxsurf.

Set-up of the hull model: NURBS surfaces, fairing and control of hull lines, including sections, waterlines, buttocks and diagonals.

Calculation of the main hydrostatic quantities: displacement, LCB, VCB, surfaces and hull coefficients, with introductory notes on trim and stability.

Limitations of digital tools and the need for critical control of the results by the designer.

7. Hull Coefficients and Hydrostatic Parameters

Waterplane coefficient, block coefficient, prismatic coefficient and midship section coefficient. Relationship between the various coefficients and their influence on volume distribution, resistance and hull behaviour. Longitudinal and vertical centre of buoyancy, LCB and VCB.

8. Weight Estimate and Loading Conditions

Organisation of the weight estimate. Fixed and variable weights, LCG, TCG and VCG. Relationship between weight distribution, longitudinal trim, stability and structural loads. Loading conditions: light craft, half load, full load, minimum and maximum operating conditions. Importance of the iterative update of the weight estimate within the design spiral.

9. Stability and Safety of Sailing Yachts

Initial static stability and overall stability. Righting moment, GZ lever arm, GZ curve and AVS. Influence of hull shape, beam, centre of gravity, freeboard, deckhouses, cockpits and flare. Effects of free surfaces in tanks, movable ballast, flooding and downflooding angle. Introduction to longitudinal stability. ISO 12217-2 and preliminary STIX calculation.

10. Sail Plan and Sailing Yacht Equilibrium

Types of rig and sail plan nomenclature. Preliminary sizing of sail area. True wind, apparent wind and points of sail. Centre of Effort, CE, and Centre of Lateral Resistance, CLR. Lead, yacht balance, weather helm and lee helm. Equilibrium between aerodynamic and hydrodynamic forces when sailing upwind.

11. Hull Appendages

Classification of appendages: lifting appendages, steering appendages and parasitic appendages. Long keel, fin keel, bulb, lifting keel, canting keel, daggerboard and canard. Single rudders, twin rudders, skeg rudder and spade rudder. Lateral area, wetted surface, span, sweep, taper ratio and aspect ratio. Hydrodynamic profiles, Reynolds number, angle of attack and introductory notes on the structural verification of rudder and keel.

12. Preliminary Structural Verification of Appendages, Rudder Stock and Keel-Hull Connection

Introductory notes on the preliminary structural sizing of hull appendages. Calculation of loads acting on the rudder and rudder stock. Preliminary verification of stock, blade, bushes and bearings according to criteria applicable to recreational craft, with reference to ISO 12215-8 and historically used methods such as ABS Offshore Racing Yachts.

Keel-hull connection: structural function of the flange, keel bolts or studs, floors, longitudinal reinforcements and hull structure. Load transfer between keel, bolts, internal structure and hull.

Introduction to the main load cases for the verification of a fixed keel: keel self-weight, 90-degree knockdown, vertical loads, longitudinal impact and grounding. Introduction to ISO 12215-9 criteria for sailing craft appendages, with reference to the verification of keel bolts/studs, contact pressures and internal supporting structure.

13. Interior and Exterior Design Applied to Yachts

Integrated design of hull, deck and interiors. Relationship between hull geometry, structures, internal volumes and deck layout. Two-dimensional sketches as the basis of the project: plans, profiles and sections. Introduction to ergonomics, comfort and human factors. Anthropometry, percentiles and minimum dimensions for passageways, stairs, seats, berths, sanitary spaces and helm stations. Floorboard level, internal headroom, cockpit and relationship between deck and underlying volumes. Use of 3D software for verification and presentation of exterior and interior design.

14. Preliminary Design of a Sailing Pleasure Craft

Application of the topics covered during the course. Market analysis, definition of main design parameters, hull development, appendages, sail plan, deck layout, 2D interiors, 3D exterior model, preliminary weight estimate and stability verification. Preparation of drawings and technical design report.

15. Performance Validation

Velocity Prediction Program, general principles, inputs and outputs. Polar curves, VMG, equilibrium between aerodynamic and hydrodynamic forces. Introduction to rating rules, in particular ORC. Use of CFD in yacht design and comparison with towing tank testing. Role of validation tools in preliminary and advanced design.

16. Naval Architecture of Motor Boats

Main typologies of motor boats and motor yachts. Design requirements: maximum speed, cruising speed, range, number and type of engines, propulsion system, design category and intended use. Preliminary parameters: LWL, BWL, displacement, power, tank capacity and propulsive efficiency.

17. Navigation Regimes of Motor Boats

Speed-Length Ratio. Length Froude Number and Volume Froude Number. Displacement, semi-displacement and planing regimes. Displacement hulls: sectional area curve, prismatic coefficient and position of the centre of buoyancy. Semi-displacement hulls: transition, resistance hump and dynamic lift. Planing hulls: hydrodynamic lift, trim, LCG, LCB, deadrise, chines, spray rails, steps and Savitsky method. Resistance, effective power, installed power, propulsive efficiency and range.

18. Stability of Motor Boats and Motor Yachts

Principles of stability of motor vessels. Influence of vertical centre of gravity, metacentric height GM and hull shape on vessel behaviour. Natural roll period as an indicative parameter of initial stability and onboard comfort.

Simplified stability checks for pleasure craft: wind heel, passenger heel, residual freeboard and limiting operating conditions. Reference to ISO 12217-1 and practical example of stability verification.

Introduction to damage stability for larger units: subdivision, watertight compartments, residual buoyancy, final flooded condition and downflooding risk.

Introduction to the principles of probabilistic damage stability according to SOLAS, with reference to the subdivision index, probability of survival after damage and comparison between required and attained index.

19. Preliminary Design of a Motor Boat

Application of the topics covered during the course. Market analysis, definition of vessel mission, choice of navigation regime, preliminary sizing, hull development, displacement and weight estimate, resistance and power estimate, engine selection, range, deck layout, interiors and preliminary stability verification. Preparation of drawings and technical design report.

20. Peer Review and Final Presentation

Project review of the submitted work. Critical discussion of design choices. Comparison between alternative design solutions. Presentation of the preliminary design, drawings, technical report and defence of the design choices during the examination. Completion of the preliminary sailing yacht project and motor boat project is a necessary condition for admission to the examination.

 

Readings/Bibliography

Recommended Textbooks and Reference Material

The teaching material provided during the lectures is an integral part of the course and represents the main basis for exam preparation.

Main reference textbook for exam preparation

• Lars Larsson, Rolf E. Eliasson – Principles of Yacht Design

This textbook is recommended as the main reference for exam preparation, particularly for topics related to naval architecture, hull design, stability, resistance, sail plan, appendages and the general approach to preliminary yacht design.

Further reading

• Francis S. Kinney – Skene’s Elements of Yacht Design, Dodd Mead & Company, New York

• Steve Killing, Douglas Hunter – Yacht Design Explained, W.W. Norton & Company

• Claughton, Wellicome, Shenoi – Sailing Yacht Design – Theory

These books are suggested as further reading to deepen the topics covered in the course, with particular reference to yacht design culture, hull lines, volume distribution, stability, performance and the theoretical aspects of sailing yacht design.

Teaching methods

The course is delivered through lectures, design exercises and, when necessary, remote teaching activities held by the lecturer.

During the course, students are strongly encouraged to start developing their assigned projects progressively, applying the theoretical contents discussed during the lectures.

During the teaching period, the lecturer will also hold intermediate project reviews, aimed at checking the progress of the work, identifying and correcting possible critical issues, and guiding students in the development of the design deliverables required for the final examination.

Assessment methods

Assessment Methods

The assessment will be based on the development of two individual preliminary design projects: one sailing yacht with auxiliary engine and one motor boat.

Each project shall include the required technical drawings, design documents and a descriptive report explaining the main design choices.

The successful completion of both projects with a sufficient grade is a necessary condition for admission to the oral examination.

The oral examination will consist of a critical discussion of the design choices made by the student, with reference to the topics covered during the course and to the applicable regulations. The student will be required to demonstrate sufficient knowledge of the subjects presented in the lectures, the ability to connect theory and design practice, and technical awareness of the solutions developed in the project work.

Final grade scale:

Obvious gaps in a significant number of topics covered in the course and analytical skills that emerge only with the help of the teacher, expression in generally correct language → 18-19;
Preparation on a limited number of topics covered in the course and independent analytical skills only on purely executive issues, expression in correct language → 20-24;
Preparation on a wide range of topics covered in the course, ability to analyse and summarise, mastery of specific terminology → 25-29;

Teaching tools

Teaching Support Tools

Teaching activities will be supported by the use of a whiteboard, computer-based presentations, digital teaching material and, where appropriate, preliminary modelling and verification tools used in yacht and naval design.

During the course, the following tools and supports may be used:

• digital presentations;

• diagrams and sketches developed on the whiteboard;

• examples of technical drawings and design reports;

• 2D and 3D models to support project understanding;

• commercial software for hull design and preliminary verification, such as Rhinoceros, Orca3D or Maxsurf, used for demonstration and project-related purposes;

• individual or group project reviews, also with digital support.

The teaching material provided by the lecturer will be made available, where possible, in digital format through the institutional platforms of the University, in order to facilitate consultation by students.

In order to ensure accessibility, students with disabilities or specific learning disorders may refer to the relevant University services and agree, according to the procedures established by the University, on any support measures or access arrangements for the teaching material.

Artificial intelligence may be used as a support tool for individual study, for example to reorganise notes, generate review questions, clarify theoretical concepts or improve the structure of written project documents. Its use, however, does not replace the student’s personal work, critical understanding of the topics, or responsibility for the design choices presented during the examination.

Office hours

See the website of Giovanni Ceccarelli