Yacht and High Performance Craft

Learning Outcomes

Knowledge and Understanding

Having successfully completed this module, you will be able to demonstrate knowledge and understanding of:

• Understand the procedures for extrapolating model tests data to full scale.
• Appraise the dynamometer and transducer types appropriate to particular model test arrangements
• Understand the mechanics and predict the performance of sailing and high performance power craft, including hovercraft and hydrofoils.
• Demonstrate a knowledge of the most common types of full scale trials used to determine a vessel's performance
• Perform analysis of model tests in order to undertake performance prediction studies.
• Appreciate and describe how the basic mechanics in each case are applied in simplified design scenarios.
• Argue the appropriateness of the type of power craft chosen under economic and sustainability considerations.
• Have an understanding of the physical and mechanical processes involved in routine model test procedures for both sailing and power craft
• Determine appropriate test methods to evaluate different aspects of power craft design.
• Describe force balance, drag components, resistance approximations, stability considerations and theoretical/experimental methods for performance estimation.
• Have an understanding of the process by which model test data can be used for performance prediction.

Learning Outcomes

Having successfully completed this module you will be able to:

• C1/M1 Students are expected to apply a comprehensive knowledge of mathematics and engineering principles to solve complex engineering problems associated with predicting the resistance and propulsion and balancing the forces and moments acting on high-performance marine craft. This is assessed as part of the coursework and the final assessment. C2/M2 Students have to analyse model scale experimental data to determine the top speed of a planing craft as part of the coursework assignment. As part of their final assessment they have to use different empirical data to justify different design choices. In both cases they have to consider the uncertainty of the data being used. C4/M4 There is a discussion session where students are assigned different research papers which they have to critique and summarise to other students, receiving formative feedback as part of the session. C12/M12 The students assess the performance of a planing hull form in the towing tank and assess trim optimisation to maximise the top speed for a fixed installed power. This is assessed in a group presentation and individual discussion questions. C16/M16 Students have to work as part of a group to obtain lab data and present their performance prediction as part of a team, while delivering their individual contribution. This is assesssed as part of the coursework where they have to evaluate their contribution to the group work alongside the other team members. C17 The students have to present a technical paper they have reviewed to their peers as part of a formative discussion activity. They also have to present their analysis of towing tank data as part of a group presentation to their peers and lectures.This is assessed as part of their coursework.

Subject Specific Intellectual and Research Skills

Having successfully completed this module you will be able to:

• Be able to critically appraise and utilise results from model tests carried out by commercial facilities.
• Understand the mechanics, performance and design considerations relevant to a range of high speed power craft
• Be able to specify appropriate model test programmes in support of a new vessel design.
• Formulate and resolve analysis necessary to assess stability and performance of high performance craft.

Transferable and Generic Skills

Having successfully completed this module you will be able to:

• Work within a group to undertake experimental testing, analyse and report the results
• Appreciate and critique technical publications related to basic analysis and design of vehicles considered.

Subject Specific Practical Skills

Having successfully completed this module you will be able to:

• Undertake experimental testing including preparing the setup of the model, acquiring data, analysing and presenting the data in oral and written format.

Overview of Hovercraft and Surface Effect Craft:

Hovercraft types: skirt configurations. Heave, Roll & Pitch Stability mechanisms. Thin jet theory and thick jet theory (equilibrium case). Plenum chamber and orifice flow theory. Simple stability analysis. The influence of internal ducting losses and fan characteristics upon the powering requirements. Hovercraft over water. Wavemaking, trim and C.G. rise, theoretical data, experimental comparison with wave pattern measurement.

Hydrofoils:

Principal characteristics of existing craft. Surface piercing and submerged foil systems. Stability in heave, pitch and roll. The effects of free surface and depth immersion on foil performance. Two dimensional lift and drag characteristics and impact on hydrofoil design. Spanwise loading on surface piercing struts, interference between foils in tandem. Cavitation and ventilation characteristics and their impact on hydrofoil design. Overall craft performance: lift/drag ratios over a range of speeds.

Sailing Performance:

Basic aerodynamic and hydrodynamic axes, apparent and true wind vector diagram, conditions of equilibrium, the beta-relation between apparent wind angle and the aerodynamic and hydrodynamic drag angles. Overall yacht performance polar diagram.

The rig polar diagram and proper sail settings in moderate weather. Sail interference effects (slot effect). Overall drag breakdown for hull. Centres of effort and lateral resistance from wind tunnel and towing tank data, sailing balance.

Semi-Displacement Round Bilge Forms:

Changes of hull form as flow regime changes with increasing Froude Number. Sinkage and trim characteristics of semi-displacement forms. NPL round bilge series and other data sources.

Planing Hull Forms:

Flow conditions under planing surface: spray root, spray sheet and fully wetted regions. The use of steps and spray rails. Forces and conditions of equilibrium. Design data and formulae.

The effects of appendages and propellers. Dynamic stability of planing craft; longitudinal stability and porpoising. Roll stability and broaching behaviour. Craft behaviour in a turn. Advanced performance prediction: comparison between experimental data and predictions from fluid finite element programs. Loading - slamming phenomena, classical methods of assessment, empirical methods.

Catamarans and Trimarans:

Relations between wetted area, deck area, displacement and length for monohull, multihull and

SWATH types and implications for power requirements. Aspects of wave and viscous drag interference as a function of craft configuration. Data sources and scaling procedures.

Teaching methods include :

• lectures ( with pre-prepared lecture note handouts) .
• tutorials carrying out analysis in a design context.
• laboratory class (4 hours each), made up of the actual laboratory time, prepatory taught material and a post-experiment analysis tutorial. Student would then prepare a detailed assignment based around powercraft performance.
• Example sheets and directed self-study in the areas of hovercraft, hydrofoils, planing craft and sailing performance and semi-displacement craft.

Learning activities include:

• Reading recommended publications.
• Expertise in carrying out hydrodynamic testing with a full understanding of instrumentation systems and error analysis.
• Understanding inclusion of simplified analyses in design context.

Feedback and student support during module study:

Formative assessment:

• Questioning students on their understanding. Through design applications and via marked example sheets. Interaction throughout laboratory experience and provision of feedback on assignments during module.

Relationship between the teaching, learning and assessment methods and the planned learning outcomes:

• Theory alone provides understanding of theory not necessarily its application. Experiments and tutorials are essential to the synthesis of different related analyses being combined in a design context. This is achieved through specifically designed examples.

Summative

This is how we’ll formally assess what you have learned in this module.

Referral

This is how we’ll assess you if you don’t meet the criteria to pass this module.

Repeat

An internal repeat is where you take all of your modules again, including any you passed. An external repeat is where you only re-take the modules you failed.