OVERVIEW

The teaching unit provides fundamental knowledge in aerodynamic, hydrodynamic, and structural analysis, forming the basis for understanding the physics and the behavior at sea of fixed-keel monohull sailing vessels, with the aim of developing and completing their design.

AIMS AND CONTENT

LEARNING OUTCOMES

The course aims to acquire the basic skills necessary for the design of sailing ships with the study of specifically inherent multidisciplinary topics .

AIMS AND LEARNING OUTCOMES

The main technical learning objectives include:

• understanding the physical phenomena that govern the behavior of a sailing yacht and the related engineering modeling;
• understanding and analyzing the dynamics and equilibrium of sailing trim conditions;
• critically assimilating methods for computation, experimentation, and data acquisition (mathematical models, systematic series, wind tunnel testing, onboard measurements, etc.);
• mastering design methods and performance prediction techniques for yachts;
• acquiring transversal analytical design skills.

In addition, the soft skills will be developed through group design activities, including functional-technical literacy and personal competence in applied contexts. These include: the ability to use, process, and evaluate information; argumentative reasoning skills; the ability to manage social and professional interactions; a collaborative attitude; and constructive communication in diverse environments.

PREREQUISITES

Given the interdisciplinary nature of the subject, a solid knowledge of the following areas is essential:

• ship hydrostatics and stability
• naval architecture
• ship structures

TEACHING METHODS

The course adopts a blended teaching approach:

• Theoretical lectures (50%)
• Group-based design project of a sailing yacht – laboratory activities (50%)

Students with valid certifications for Specific Learning Disorders (SLDs), disabilities or other educational needs are invited to contact the teacher and the School's contact person for disability at the beginning of teaching to agree on possible teaching arrangements that, while respecting the teaching objectives, take into account individual learning patterns. Contacts of the teacher and the School's disability contact person can be found at the following link Comitato di Ateneo per l’inclusione delle studentesse e degli studenti con disabilità o con DSA | UniGe | Università di Genova

SYLLABUS/CONTENT

Main topics covered in the unit (including proposed applications):

BASIC DESIGN
Nomenclature. Points of sail and maneuvers. Types of sails and rigs. Design criteria. Historical overview. The ORC rating certificate: data interpretation and practical use. Applied exercise: Collection of statistical ORC data and definition of the main characteristics of a sailing yacht based on operational requirements and design constraints (charter vs. cruise vs. racer vs. cruiser-racer vs. explorer).

BASIC DESIGN (continued)
Design criteria. Yacht design methodology. Definition and main features of the vessel. Principal dimensions – statistical data and reference yachts. Hull shape layout. Main software used in the design process. Marine CAD tools. Additional statistical data relevant to early design stages. Weight and production cost analysis. Regulations: hull length (Lh). Technical specification. Applied exercise: Introduction to preliminary general arrangement drawings.

STABILITY
Transverse and longitudinal stability at small angles. Dellenbaugh angle and roll period. Righting arm curve. Righting moment in waves. Dynamic stability. ISO 12217-2 and LY3 stability assessments. Applied exercise: Regulatory stability verification and limitations (dynamic effects).

HYDRODYNAMICS (hull)
Hull resistance under power. Viscous resistance. Wave resistance. Delft systematic series. Residual resistance. Heeling resistance. Added resistance. Auxiliary engine power. Propeller diameter. Propeller resistance under sail. Applied exercise: Estimation of total resistance with focus on appendage drag.

SAILING MECHANICS
Wind triangle. True wind and apparent wind. Points of sailing and tacking. Yacht speed polar diagram. Lift and drag-generating surfaces and profiles. Fluid dynamic forces – lift and drag. Aerodynamic and hydrodynamic forces. Equilibrium in various planes. Equilibrium equations. Centers of effort. Sail lead. Helm balance. Performance prediction. Performance prediction programs. VPP calculation methodology. Applied exercise: Calculation of true and apparent wind, velocity triangles, identification of design sailing conditions, use of lift/drag curves vs. drive/lateral forces; evaluation of equilibrium points.

AERODYNAMICS (sails)
Sails. Flow around sails. Sail shape. Sail twist. Mast interference. Hazen model for sail and rig aerodynamics. Calculation of aerodynamic forces with the ORC VPP model. Statistical parameters for the sail plan. Rigging geometry (overview). Applied exercise: Estimation of aerodynamic driving and lateral forces, and aerodynamic resistance - sail plan definition.

HYDRODYNAMICS (appendages)
Flow around a foil. Lifting line theory. 2D foil design. Planform, taper, sweep and tip shape optimization. Lift and induced drag on the boat. Winged keels. Forward rudder. Twin keels. Canting keels. Applied exercise: Estimation of lift and drag; vector composition and projection along sailing direction - appendages plan definition.

HULL DESIGN AND RULES
Design category (Directive 2013/53/EU). Definition and navigation limits of design categories for recreational craft under the Italian flag. CE certification – Harmonized directives and standards. Construction and classification rules for recreational craft with Lh ≤ 24 m. Applied exercise: Development of a structural layout for a sailing vessel.

SAIL DESIGN & CONSTRUCTION
Design and manufacturing of sails. Aerodynamic flow analysis. Materials and properties. Types of sails and manufacturing methods. Sailmakers and organizational structures. Applied exercise: Definition and integration of the sail system and rig within the hull structures.

MAST & RIGGING
Components of mast and rigging. Scantling of mast and rig: direct calculation, dock-tuning, application examples and simplifications. Skene’s method. Classification societies’ approaches (DNV, Bureau Veritas). Nordic Boat Standard method and its variants.
Applied exercise: Scantling of a rig system according to rule requirements (NBS or others).

KEEL & APPENDAGES DESIGN
Calculation examples. Design of the ballast keel. Yacht heeled at 90°. Longitudinal grounding. Scantling according to ISO 12215-9. Case studies. Combined loading. Structural strength of appendage-hull joints (flat and custom couplings). Design of keel fins and bolts. Compression at the keel-hull contact area. Applied exercise: Scantling of the main structural elements of the hull, especially those stressed by the rigging system, possibly including direct calculations.

RUDDER & KEEL
Rudder design. Dimensioning according to ISO 12215-8. Bending moment on rudder, loads on the rudder tube, and torque. Rudder stock design. Shaft deflection between bearings. Equivalent diameter at shaft head. Rudder shaft bearings, pintles, and gudgeons. Rudder blade. Practical rudder and keel design. Applied exercise: Regulatory dimensioning of the rudder and associated components for a sailing yacht.

DECK PLAN
Selection and sizing of deck equipment. Loads on sheets and halyards. Jib handling system. Mainsail handling system. Deck layout and running rigging. Applied exercise: Design of the deck plan and selection of key handling components (winches, blocks, fairleads, etc.).

RECOMMENDED READING/BIBLIOGRAPHY

Main:

L.Larsson, R.Eliasson, M.Orych “Principles of Yacht Design”, 4a ed., International Marine / McGraw-Hill Education, 2014.

B. Piaggio, C.M. Rizzo, "Slides e appunti Lezioni del corso"

Offshore Racing Congress, “ORC VPP Documentation”, ORC 2023

Regolamenti delle Società di Classificazione e Normative ISO illustrate a lezione

Additional:

C.A.Marchaj, “Aero-Idrodinamica della Vela”, Mursia, 1987

J.W. Sloof, "The Aero- and Hydromechanics of Keel Yachts"

P. E. Liguori, “Le vele”, Hoepli, 2006

R. Garret, “Fisica della vela”, Zanichelli, 1994

I. H. Abbot, A. E. von Doehnoff, L. S. Stivers jr, “Summary of airfoil data”, NACA

TEACHERS AND EXAM BOARD

LESSONS

LESSONS START

As scheduled by the official academic calendar of the Polytechnic School (see the EasyAcademy portal: easyacademy.unige.it)

Class schedule

SAILING YACHTS DESIGN

EXAMS

EXAM DESCRIPTION

The final exam consists of an oral assessment and requires the completion and presentation of the group project developed during the course.

The final grade is based on the following criteria:

• Theoretical and practical mastery of the subject and understanding of its design implications (50%)
• Professional and practical competence demonstrated through the project work (50%)

ASSESSMENT METHODS

The project execution and each candidate’s responsibility for a specific area of expertise within the project constitute the first part of the final exam. The second part consists of theoretical questions related to the topics of aero-hydrodynamics and structural design covered within the unit, as well as their multidisciplinary implications.

Candidates, while working within the group, are individually evaluated based on their primary area of competence developed within the project, their understanding of the overall project vision, key design choices, and the underlying theory behind each phase of the work. Presentation skills, organizational ability, and command of technical language are also assessed.

FURTHER INFORMATION

For students who have not attended the course in person, the same procedure and project submission requirements apply. This entails the presentation of the project in all its components, with responsibility for at least one area of expertise for which the candidate has performed detailed calculations (hull design and stability, resistance, sail rigging, sizing and positioning of appendages, structural scantling of hull, mast and appendages), serving as the starting point for the exam.