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Home › Dry Dock › Rudder and Sea Chests (Sea Chests and Sea Valves)
Operational guide · Operational procedure

Rudder and Sea Chests (Sea Chests and Sea Valves)

Rudder, sea-chest and shell-valve examinations follow UR Z3/class Rules and surveyor scope; opening extent and IWS/EDD alternatives do not follow a universal instruction.

ruddersea chestsea valvesrudder

Operational Explanation

Rudder, sea-chest and shell-valve examinations follow UR Z3/class Rules and surveyor scope; opening extent and IWS/EDD alternatives do not follow a universal instruction.

Regulatory Reference

IACS UR Z3 Rev.8, applicable class Rules and attending surveyor.

UR Z3.2.3 covers sea chests, gratings, connections, valves and fastenings. Valves and cocks need not be opened more than once during a Special Survey period unless the surveyor considers it necessary: check the opening history before defining scope. IACS UR Z3.2.3.

For the rudder, Z3.2.4 requires examination of visible parts and ascertainment/recording of bearing clearances. Lifting the rudder, removing inspection plates and pressure testing depend on the surveyor’s assessment. Link each reading to its position and compare it with applicable limits. IACS UR Z3.2.4.

Rudder examination also has a statutory basis: HSSC 2025, annex 1, (CB)3.1.1–3.1.2 includes examination of the rudder and recording measured rudder-bearing clearances during cargo bottom inspections. For passenger ships, (PR)5.2.2.1 also includes sea chests and strainers. Applicable Rules and approved data determine dimensional acceptance limits. HSSC 2025, annex 1, CB3.1; PR5.2.2.1.

Scope of Application

Out-of-water access is the most complete opportunity; valve/cock opening frequency and consecutive-IWS alternatives follow Rules and approved arrangement.

Procedure / How to Complete It

  1. Prepare access and examination scope.
  2. Measure rudder clearances as required.
  3. Open/examine sea valves/chests where required.
  4. Use alternatives only with formal approval.
  5. Perform functional/leak tests after maintenance.

Practical Example

A valve is opened within the required Special Survey extent, not necessarily at every docking by a page rule.

What Typically Goes Wrong

Saying necessarily dry dock or always open every sea chest/valve while ignoring surveyor and approved IWS/EDD.

Common Mistakes Mistake Library

MistakeConsequenceHow to Avoid It
Saying necessarily dry dock or always open every sea chest/valve while ignoring surveyor and approved IWS/EDD.Non-compliant decision or treatmentFollow the approved arrangement and applicable sources

What the PSCO Checks

Check recorded clearances and findings, valve/connection maintenance and restoration, leaks and open defects. Compare post-maintenance tests and survey status with actual condition; a worklist marked complete is insufficient.

Operational Tips

Preparation checklist

FAQ

Is every valve opened every docking?
Not universally.
Can IWS change scope?
Only under approved arrangement and Rules.

Related Topics

Tail Shaft SurveyBottom Survey and In-Water Survey

Last substantive revision of this page: 16 September 2026 · page fingerprint 1193682a0596