THE DRAWING OFFICE

Introduction

The Drawing office is probably one of the most important organs of the shipyard entity. Without the drawing office and its draughtsman, the marine engineers, technicians and artisans will have no “map” to follow to build the ship that was designed by the Naval Architect.

Drawing Office Responsibility

The drawing office and the draughtsman working there are responsible for producing drawings for hull and outfit of the ship. They must produce the following:

Structural Drawings

• Structural drawings are to be in accordance with the Classification Society Rules and Regulations and subject to their approval.

General Arrangement Drawings

• GA’s are to include outfit plans, piping arrangements, air conditioning etc., and allow for statutory requirements.

The Traditional vs. The Modern Method

The Traditional Method

Traditionally, prior to the use of computers and dedicated draughting software, the Drawing Office operated in the following manner:

• A full faired lines plan was drawn manually (pencil/ink on paper/film, battens & weights for curves). This lines plan consists of the body plan, profile & waterline plan as was discussed earlier.
• A table of offsets was then produced – ½ breadths, height of decks, stringers etc.
• A drawing loft was then used where full size lines were drawn on a loft floor & faired.
• Afterwards, a Scrieve board was produced. A Scrieve board is a wooden board with body sections at each frame.
• Finally, templates were produced for cutting frames & plates.

An example of a drawing loft used in the past to draw full scale lines for the purpose of producing templates for frames and hull plates is shown below.

The dimension terminology used by the draughtsman of old which are still used in today’s modern techniques is called Molded dimensions. Molded dimensions refer to dimensions taken to the inside of the plating, and which is shown below. The following Molded Dimensions are referred to:

Molded Depth: It is measured from the molded base line (inboard of the keel) to the heel of the upperdeck (freeboard deck) beam at the ship’s side amidships.

Molded Breadth/Beam: It is measured at the midship section of the ship. This is the maximum molded breadth of the ship, taken from the centreline to the inside of the hull plating.

Molded Draft: It is measured from the molded base line (inboard of the keel) to the Design Waterline of the ship.

Next topic Loads, Structures and Materials »