ISO 6050:1987

Overview

ISO 6050:1987 is an international shipbuilding standard that specifies the symbols used to identify bulbous bows and side thrusters on ship hulls. The standard defines the required dimensions, location and paint colour for these hull markings so that the presence and position of a bulbous bow or a side thruster are clearly indicated on both port and starboard sides. ISO 6050 was prepared by ISO/TC 8 (Shipbuilding and marine structures) and published in 1987.

Key topics

• Scope: Symbols for bulbous bow and side thruster to be used on ships’ hulls to indicate their presence.
• Symbol dimensions: Minimum dimensions are specified (shown in Figures 1 and 2 of the standard, in millimetres). If larger symbols are used, the dimensional proportions defined in the figures must be retained.
• Location requirements:
  • Bulbous bow symbol: placed at the forward end of the ship on both port and starboard sides, clearly visible above the maximum draught level and pointing toward the bow.
  • Side thruster symbol: placed on both port and starboard sides above the maximum draught level and, as far as possible, on the vertical line passing through the thruster’s position.
• Paint and construction: Symbol outlines shall be formed of weld beads and painted in a colour that contrasts with the ship’s shell painting to ensure visibility.

Applications

ISO 6050:1987 provides practical guidance for consistent hull marking and is useful for:

• Shipbuilders and shipyards implementing final hull outfitting and markings
• Naval architects and marine designers specifying hull markings on plans and as‑built drawings
• Classification societies and surveyors verifying compliance during construction and surveys
• Shipowners and operators for consistent identification of hull features
• Ports and pilotage services that rely on visible hull indicators for berthing and handling

Benefits include improved onboard identification of propulsion/appendage features, clearer communication between builders/operators/surveyors, and standardized visual cues for maintenance and emergency response.

Related standards

• ISO 6050 complements other shipbuilding and marine-structure standards developed by ISO/TC 8. For comprehensive compliance, consult other ISO shipbuilding standards and classification society rules relevant to hull markings, painting and structural welding.

Keywords: ISO 6050:1987, bulbous bow symbol, side thruster symbol, shipbuilding standard, ship hull markings, symbol dimensions, paint colour, weld beads.