Ship Construction and Naval Architecture Fundamentals
Core concepts
Candidates must understand hull form terminology: length between perpendiculars, beam, depth, draught, freeboard, camber, sheer, flare, and rake. Know the structural members: keel, keelson, floors, frames, stringers, longitudinals, bulkheads, decks, and shell plating. Understand transverse and longitudinal framing systems and their trade-offs. Learn the meaning of displacement, deadweight, lightweight, gross and net tonnage, block coefficient, midship section coefficient, prismatic coefficient, and waterplane coefficient. Understand stability terms: centre of gravity, centre of buoyancy, metacentre, metacentric height, righting lever, free surface effect, and the inclining experiment.
Common traps
Questions often confuse displacement with deadweight, or gross tonnage with displacement. Watch for the difference between transverse and longitudinal framing in resisting bending moments. Free surface effect reduces metacentric height and is frequently misapplied to longitudinal stability. Remember that adding weight high up raises the centre of gravity and reduces stability.
Worked example
A box-shaped vessel 100 m long, 20 m wide floats at 6 m draught in seawater (1.025 t/m³). Displacement = 100 × 20 × 6 × 1.025 = 12,300 t. If 300 t of cargo is added, the parallel sinkage = 300/(100 × 20 × 1.025) ≈ 0.146 m. Rule of thumb: for a box-shaped hull, tonnes per centimetre immersion = L × B × ρ / 100.
Study approach
Sketch hull sections and label structural members. Practise coefficient and stability calculations, and link structural design to loading conditions and stress.