Design Engineering basically revolves around various factors like principles of ship design, ship structure, compartment numbering, submarine design, piping systems and various other ship structural elements.

Design Engineering of ships looks in to various factors before it is confirmed. It undergoes various changes and modifications each time while considering stability, hull shape, displacement, protection, maneuverability, cruising range etc.

Importance of Design Engineering

Design Engineering plays a vital role throughout the lifetime of a ship. Appropriate specification is the basis of a ship design. A naval architect uses these specifications as guideline to further move on with their project outline, dimensions, layout and to prepare the initial rough draft. Once the initial rough draft is assessed and approved, a preliminary hull design and overview of ship’s propulsion is made with progressive changes at each stage. Designs of large and intricate also include sail plans, electrical schematics and the interiors, producing an overall plan for the ship. Stress, strain and longitudinal bending are some of the other concerns that are verified at each step of the process. Stress is defined as the load per unit area and it corresponds to tension and torsion. While strain is explained as deformation per unit length, longitudinal bending mainly constitutes sagging and hogging. Sagging is the condition when the hull is bending upwards and when ship is supported more at ends. At the same time hogging is the condition when the centre of the keel is bending downwards. Hogging and sagging is experienced when a wave of same length as the ship hits but sagging is initiated when the ship is in the trough of two waves. The main deck undergoes compression and tension during sagging and hogging respectively.

Some of the key structural elements in Design Engineering:

• Keel
• Framing
• Bottom
• Plating
• Decks
• Bulkhead
• Doors
• Hatches

Each structural element is equally important because when the keel acts as the centre backbone of the ship, framing is the ribs, bottom comprised of keel and framing is the cellular region, plating is the skin and the list goes on gaining importance on each point. Another system followed in ships since 1949 is the numbering of decks, frame, compartment and so on. Letters are also normally designated like for eg A for supply & storage, T for trunk, W for water tank etc.

When it comes to submarines naval architects prefer hulls made of HY-80 or HY-90 steel with inner hull with pressure and outer one being the non-pressure hull. Single hull designs are usually seen in US submarines while the double hull designs in those of Russians. The single hulled submarines have larger interior volume while the double hull designs are easier to manufacture with the ability to absorb damage.