The RC Racing Yacht Explained
How to use this book.
Many readers may think that section 2 is more than is required to understand a yacht. However reference is made in section 3 to the many aspects of “theory” which are essential in order to follow the text. It is really best to browse section 2 before tackling section 3 and then go back to look at section 2 carefully as the need arises.
This book can be downloaded using a modern printer to appear like the original on A4 paper. The aberrations in the presentation of the text on the screen are the result of the change to html that has to be made to upload to the web.
Click on any chapter to open it.
Table of Contents
Section 1
Chapter 2 The monohull racing yacht. 3
Section 2
Chapter 3 The “theory” needed to understand model yachts. 6
Mathematical equations and units. The triangle of forces. Relative motion. Framed structures. Centre of gravity. Centre of volume. Centre of area. Second moment of area. The concept of pressure. Flotation. Stability of floating vessels. Metacentre and metacentric height. Potential energy and kinetic energy. Pressure energy.
Chapter 4 Air and water as they act on a yacht. 17
Water
The structure of water when it is at rest. The motion of water near to the surface resulting from wind blowing over it. Pressure variation in water at rest.
Air
Air as a gas. The structure of a gas. The action of wind on a lake.
Chapter 5 The resistance to the motion of a surface vessel. 21
Introduction. Forms of motion of surface vessels. Skin drag. Resistance to motion resulting from wave making. The idea of a critical speed.
Flow patterns and aerodynamic lift. The effect of an aerofoil on the upstream flow. Pressure distribution round an aerofoil. Separation. Lift and drag. Aerofoil data. The effect of aspect ratio. Aerofoils at high angles of attack.
Section 3
Chapter 7 Leeway and the thrust versus speed graph for a model yacht 35
Chapter 8 How a yacht beats to windward. 37
Tacking. Apparent wind. Leeway. Vector diagram for the beating yacht. Angle of attack of the main sail. Forces on sails
Chapter 9 Flow visualisation for the beating yacht. 43
The Hele-Shaw equipment. The shape of sails. The single sail in the Hele-Shaw rig. The Bermuda rig in the Hele-Shaw equipment.
Chapter 10 The polar performance diagram explained using the swing
rig version of the Bermuda rig. 50
The polar performance diagram. The swing rig. Combined force on a swing rig. The sailing diagrams. Implications of the polar diagram.
Chapter 11 The real flow over a Bermuda rig 56
Vortices and breakaway. Practical testing. Photographs.
Chapter 12 The geometry of the Bermuda rig as it is used in model
The sheeting mechanism. The winch. The requirements of the rig. Sheeting the fore sail. Sheeting the main sail. Sheeting the sails together. Changing to smaller rigs. Selecting a drum size. Position of the sheeting eye on the fore deck.
Chapter 13 Flow visualisation for the conventional Bermuda rig. 64
Chapter 14 The sailing diagrams for a conventional Bermuda rig. 66
Sailing diagrams for boom angles from 0° to 90°. Sailing diagrams for reaching and running.
Chapter 15 The mechanical arrangements of sailing rigs. 70
The standing rigging used for the Bermuda rig. The sail mountings. The swing rig.
The design of sails for model yachts. The sail plan. The profiles. The main sail. The fore sail.
Introduction. The section of the fin. Surface finish. Choice of section area of fin. Shape of fin.
The directional control of a yacht. The wing/stabiliser system. The fin and rudder system.
Changing course. Design of the rudder.
Low drag profile for round bulbs. Bulbs for yachts with draught restrictions. Surface finish.
Chapter 20 The hull of a racing yacht 96
Strength. Flotation. Stability. Leeway and turning. The shape of the hull.
The sailing rig. The hull and the rig. Sailing in light winds. The model yacht as a whole. Design guidelines for model yachts. Post script