Dry-Dock and UWILD Surveys

Work with EDT for periodic inspections of your towing vessels.

Dry-Dock Surveys

Depending on the service profile of a towing vessel, a periodic inspection of the complete hull of the towing vessel will need to be done.  This has to be done out-of-water – thus, a ‘dry-dock’ survey – and with the following frequency:

  • A towing vessel which operates in salt water for more than 6 months of each year needs to have two (2) ‘dry-dock’ surveys in each 5 year period of the Certificate of Inspection (COI).  The ‘dry-dock’ surveys shall have no more than 36 months (3 years) between surveys.
  • A towing vessel which operates in salt water for 6 month or less of each year needs to have one (1) ‘dry-dock’ survey in each 5 year period of the COI.

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Scope of the Dry-Dock Survey 

Part 137 of Title 46, Subpart C, defines the ‘dry-dock’ survey.  This Subpart is entitled ‘Dry-Dock and Internal Structural Survey,’ which describes completely the scope of this periodical survey.  A ‘dry-dock’ survey will cover an inspection of the external hull, propulsion, and external machinery components.  It will also examine internal structure of the towing vessel, including the ship sides, bow, stern, foundations, voids, ballast tanks, fresh water tanks, built-in fuel tanks, and bulkheads. 

Expanding or Limiting Examinations

Provisions are given to expand or limit the examinations, based on 1) accessibility and 2) external condition.  While an examination to the letter of the regulations would require access to all spaces, there are reasons why a space should not or cannot be examined.  A prime example would be a fuel tank more than 25% full; that space is neither safe for entry nor provides the surveyor/inspector with a view of sufficient tank structure.  Another instance would be a void too narrow for human entrance.  If an examination of the external structure around the inaccessible space indicates satisfactory condition, internal examination may be waived.

UWILD Surveys

The UWILD survey – UnderWater Inspection in Lieu of Drydocking (another cute acronym from our government) – is a substitute for a ‘dry-dock’ survey.  For vessels approved for this program, an external survey of the underwater portions of the towing vessel can be done by a diver, remotely operated vehicle (ROV), or other means with supplied video to the surveyor/inspector.  There cannot be two (2) consecutive UWILD surveys conducted on the same towing vessel – at least every other survey in accordance with Subpart C of Part 137, Title 46, must be done in a dry-dock or equivalent.

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UWILD Survey Conditions 

For a vessel to be considered for the UWILD survey option, the following conditions must be satisfied:

  • No obvious damages or defects have been reported to the towing vessel hull;
  • The operation of the towing vessel has been satisfactory since the last dry-docking;
  • The vessel is less than 15 years old (though there are provisions for older vessels – keep reading)
  • The towing vessel hull is made from steel or aluminum;
  • The hull is protected with a protection system.

UWILD Survey Requirements

An application for a UWILD survey will need to go through the local OCMI ninety (90) days prior to the prospective survey, with information on where, when, who is attending, how the survey will be handled, the hull protection system, and the method of inspection.  For operators with a TSMS, the requirements of a UWILD must be included in the TSMS for the UWILD to be considered.

An operator electing to have a UWILD survey should discuss this with a TPO prior to applying.  The TPO surveyor/auditor can provide advice on potential diving companies local to the operator, provisions for the survey, and other aspects of the application.

Hull Protection System 

One of the requirements for being accepted for a UWILD is a hull protection system.  ‘Hull protection systems’ can be a number of solutions for retarding corrosion of a metallic hull.  The primary hull protection is a coating – paint.  Properly applied and maintained coating on the underwater portions of the hull will reduce corrosion.  Coating maintenance includes the periodic re-application – usually at each dry-docking.  Active hull protection includes anodes and impressed current cathodic protection.  Anodes assist the coating in protecting the hull where the coating has deteriorated and protecting bare metal parts such as propellers, bearings, and external coolers.  Anodes need to be replaced periodically to continue to protect.

Towing Vessels Older Than 15 Years 

If a towing vessel is over 15 years of age, but otherwise meets the five bullet points above, it may still be allowed to have a UWILD survey.  For vessels over 15 years of age, a UWILD survey may be conducted at alternating intervals – that is, once in each 10 year span – provided:

  • The bullet points above are met (except for the 15 year or less requirement);
  • A complete set of hull thickness measurements (gauging) had been carried out at the previous ‘dry-dock’ survey.