July 22, 2021 | Circular No. 11303

Dear Member,

Further to CL11277, Transport Canada has published draft voluntary guidance for in-water cleaning of vessels. Below is some background on the subject, highlights of the draft guidance, and several questions on how / whether the guidance may affect member operations (we will incorporate member responses in our comments to TC).

It is worth noting that Transport Canada has indicated to us that it is NOT planning to implement unilateral requirements for in-water cleaning. However, under the Canada Marine Act and the Port Authorities Operations Regulations, ports may establish practices and procedures in their waters. The voluntary guidance could therefore serve as a template for such requirements.



Biofouling is the build-up of microorganisms, plants, algae and animals on a ships’ hull or other submerged structure. It is a major way that aquatic invasive species are introduced to new environments, and according to IMO, “has been identified as a major threat to the world’s oceans and to the conservation of biodiversity.” Microfouling is commonly referred to as a slime layer. Macrofouling includes large visible organisms, such as barnacles, tubeworms, and fronds of algae.


This draft voluntary guidance is addressed to Canadian Port Authorities (CPAs) and other authorities that manage port operations. TC was motivated to create the guidance due to multiple questions it received from CPAs and industry stakeholders about the permissibility of in-water cleaning of vessels. According to a survey they conducted, less than half of CPAs permit the practice in their waters.


IMO Biofouling Guidelines (2011) are intended to provide a global approach to managing biofouling, but are not widely used and are currently being reviewed by an IMO subcommittee. This review is planned for completion in 2023.

BIMCO recently published an Industry standard on in-water cleaning with capture and Approval Procedure for in-water cleaning companies (January 2021).

Parties such as New Zealand and California have set unilateral requirements limiting biofouling and conditions for hull cleaning, in addition to the IMO guidelines.


The proposed voluntary guidelines are consistent with the IMO Biofouling Guidelines, and recommend the following:

  • Cleaning with capture for international vessels.
  • That in-water cleaning be used only if micro-fouling is present (not macro-fouling), but acknowledge that in-water cleaning may be necessary even when macrofouling is present.
  • That technology to clean macrofouling undergo independent third-party testing, including criteria for capture, filtration, secondary treatment, and continuous monitoring.
  • That a request for cleaning must be made at least 10 days in advance of the scheduled cleaning date.
  • That external niche areas be cleaned whenever possible, recognizing there are challenges in ability of equipment to reach these areas.
  • Documents, including an example cleaning request form, anti-fouling coating information, recent inspection report, biofouling management plan and biofouling record book.

The guidelines also provide a decision support tool for local authorities (i.e., ports) allowing in-water cleaning, and advises that they may reject cleaning request if they deem risk too high, including because of environmental conditions such as weather on the day of cleaning.


  • Does your company perform cleaning of vessels in Canada, or does it intend to do so?
  • If yes, would the proposed guidelines affect your company’s current practices (please specify which practices, if appropriate)?
  • Do you have any other comments or concerns with respect to the proposed guidelines?

Please revert to the undersigned with comments by Wednesday July 28th.




Miako Ushio

Manager, Environmental and Regulatory Affairs