USVs, Load Lines and the issue of Exemptions.

The Load Line and exemptions for USVs

There is increased focus and drive in the Maritime industry for the use of new Technology and Automation, spurred on by a drive to reduce costs, increase safety and achieve Net Zero objectives. Of course, as with many technological advances, they tend to move faster than the rules that govern their use and adoption. A case in point is Load Lines and the potential for exemptions of the rules for the use of Unmanned Surface Vessels (USVs).

A Brief History

The basic premiss of the Load Line is to stop ships being overloaded. In our opinion, it is one of the most significant pieces of seafaring safety legislation to pass through the UK parliament, in 1876, (the Merchant Shipping Act) thanks to the unstinting efforts of Samuel Plimsoll. 

Other Maritime nations followed the UK and developed their own regulations, until they were standardised in the Load Line Convention of 1930.  

The present International Convention on Load Lines was drawn up and adopted by the International Maritime Organisation (IMO) in 1966 and entered into force in 1968. Whilst various amendments after 1968 were adopted, they never achieved positive acceptance limits and never came into force. 

The 1988 Protocol entered into force in February 2000. This harmonised the Conventions certification and survey requirements with SOLAS and MARPOL Conventions as well as revising certain regulations within the technical Annexes to the Load Lines Convention. 

Additional amendments have come into force 2005-2008 – MSC 143(77), MSC 172(79) and MSC 223(82) -, 2010 (MSC270(85), 2014 MSC 329(90). 

LOAD LINE – Basic Principles 

The principles of the Load Line Convention, looks to ensure the following:

  • Adequate structural strength 
  • Protection of safe means of access for crew 
  • Watertight integrity of ships hull below the freeboard deck 
  • Reserve buoyancy 

 The LOAD LINE Mark (AKA – Plimsoll Line) 

It comprises a circle of 300mm diameter intersected by a horizontal line 450mm in length the upper edge of which passes through the centre of the circle. The Lines are 25mm breadth.

The centre of the ring shall be placed amidships (port and starboard) and at a distance equal to the assigned summer freeboard measured vertically below the deck line. 

 Who administers in the UK? 

In the UK, the administration responsible for verifying compliance with the requirements of the International Convention on Load Lines and issuing International Load Line Certificate to ships is the Maritime Coastguard Agency (MCA). 


 The Load Line Convention applies to vessels engaged in international voyages, meeting the following criteria.

  • New ships having a length of 24m and upwards, and  
  • Existing ships for the Convention having 150 gross tonnage or more.

How do you get one? 

An initial survey of the vessel is performed prior to entry into service. This survey is a complete inspection of the structure and equipment (as indicated in the Convention). The survey is intended to ensure that the arrangements, materials and scantlings fully comply with the requirements of the International Convention on Load Lines. 

 The Certificate contains the following information: 

  • Name of Ship 
  • Distinctive Number 
  • Port of Registry 
  • Length 
  • Gross Tonnage 
  • Type of ship 
  • Freeboards (from deck line) and load lines assigned for: 
  • Date of Survey 
  • Any Conditions 
  • Endorsement of Annual Survey 

Along with the Certificate, a Conditions of Assignment document is issued. This details the Fittings, appliances and arrangements approved for the ship: Ships name, Port of Registry, Nationality, Official Number / Call Sign, Builder, Yard number, Date of build / conversion, freeboards assigned as ship of Type (A, B, or B with reduced / increased freeboard), Classification, Date and place of initial survey, sketches of side profile, superstructure deck and freeboard deck (with a note that a plan of suitable size may be attached instead of sketches) to show disposition of superstructures, trunks, deckhouses, machinery casings, extent of bulwarks, guard rails and wood sheathing on exposed deck, hatchways, gangways and other means of protection for crew, cargo ports, bow and stern doors, side scuttles, scuppers, ventilators, air pipes, companionways and other items that would affect seaworthiness. 

Tabular reports of: Doorways in superstructure, exposed machinery casings and deckhouses protecting openings in freeboard and superstructure decks, hatchways, machinery space openings and miscellaneous openings in freeboard and superstructure decks, Ventilators on freeboard and superstructure decks, Air pipes on freeboard and superstructure decks, Cargo ports and other similar openings, scuppers, inlets and discharges, Side scuttles, Freeing ports, Protection of the crew.

LOAD LINE – Exemptions 

International Load Line Exemption Certificates may be issued to ships of Convention size on international voyages in certain circumstances (see below).  

UK Load Line Exemption Certificates may be issued to ships which do not ply internationally or which are not Convention ships, for example, those which are less than 150 GT or less than 24 m in length.

  1. Under Article 6 (2) of the International Load Line Convention, when a ship “embodies features of a novel kind” it may be exempted from compliance with any provision of the Convention application of which might seriously impede research into the development of such features and their incorporation in ships engaged on international voyages; and  
  2. Under Article 6 (4) of the Convention, when a ship not normally engaged on international voyages makes a one-off international voyage. 

What if my ship is less than 24m? 

We will assume for the time being we are dealing with a UK Registered vessel. Overall we would be working under the Merchant Shipping Act 1995. 

The Specific Guidance / Regulation for a New build vessel would be “The Workboat Code, Edition 2, Amendment 1 – The safety of small Workboats and Pilot boats – A code of Practice”  

The code aims to provide, in a single document, all the information needed for the design, construction, engineering, electrical systems, hull systems, fire protection, and provision of fire-fighting, life-saving, navigation and radio equipment. It also covers manning and the qualifications needed for the senior members of the crew.  

It is important to note that the Code is underpinned through Statutory Instruments which means that it is an equivalent standard to full compliance with Merchant Shipping regulations, covering Load line and other safety and operational matters.

Vessels that comply with the Code may additionally be issued with a UK Load Line Certificate. 

So, we’ve covered the background. The issue at hand is application for Unmanned Surface Vessels

With the level of discussion we are having within the industry and with our clients, this is a hot topic and causing frustration with USV Operators keen to deploy their assets onto available and willing projects.

Those of us involved in this area of the marine world know that we have several difficulties at the moment; innovators that are new to seafaring and are finding it difficult to navigate the legal and regulatory regimes, the technology is outpacing the law and regulatory regime(s) and market opportunities across diverse fields, cargo vessels / ferries / survey etc, with everyone wanting to be “first”. 

Whilst formal legal and regulatory regimes lag behind the technology, various “bodies” resurrect or are born which offer “codes of practice”, “guidance”; this on top of UNCLOS, IMO (Colregs, SOLAS, MARPOL, STCW),  Flag State, ISO 23860, Classification Societies Rules and Regulation. 

The product innovator is generally focused on developing their product and advancing technology, rather than focussing on building a ship. The evolution here into USVs is perhaps based on the lack of barriers and limited regulatory framework for similar autonomous technology working under the surface, such as AUVs (Autonomous Underwater Vehicle). The innovators simply can’t understand why deploying similar technology onto a floating craft requires more regulation to go off and do their thing. The ex-seafarers in the company can fully understand their frustration, particularly when autonomous underwater vehicles have been in use for quite some time. 

USVs are defined by the following categories, where they are to be a UK registered MASS (Maritime Autonomous Ship Systems) vessel.

  • Ultralight – less than 7m,
  • Light – 7m -less than 13m,
  • Small 13 to less than 24m, 
  • Large – greater than 24m,
  • High Speed

Of course, each USV will have different characteristics and design criteria, so a “one size fits all” approach is not appropriate. Where some designs may be suitable for a load line exemption, a “newer” version may not, due to minor amendments to the design and Innovators pushing the envelope of capability, endurance and functionality. This is expected to remain a problem point until such times as legislation is adopted at an international level.

Where are we with regards to Legislation?

The International Maritime Organisation (IMO) continues to develop the response to the technology and is working to an agenda. Whilst this is expected to be slow to deliver, it will be International, providing consistency across multiple jurisdictions and operational regions. In the UK, guidance is available, and when combined with suitable marine knowledge, it is expected to support delivery of a safe, environmentally considerate and regulatory compliant vessel. As with many regulations, a clear understanding of the various requirements, and an ability to correctly interpret those rules, is a must in determining how to achieve this.

Maritime UK have recently released the “MASS UK Industry Conduct Principles and Code of Practice 2021 (V5)” which may provide additional insight for the industry, operators and equipment manufacturers. A link to the document is at the bottom of this article.

How to navigate the challenges

Our approach, in principal, would follow the MASS UK Industry Conduct Principles and Code of Practice; the principles of which, we feel, align with our experience in developing Failure Modes and Effects Analysis for Dynamically Positioned vessels and our work on Safety Case (UK) for Well Intervention vessels. 

Evaluation of the specification of the USV, including systems onboard (Power, Cooling, Data Transmission, Cyber Security etc), operating methodology and assessment of these against the relevant codes and guidance would be required in order to develop a plan and provide advice on achieving the required “tests” to gain acceptance for operating in the UK.

The recent guidance document on MASS is available here:

MASS UK Industry Conduct Principles and Code of Practice 2021 (V5) | Maritime UK

If you would like more information, or to have a general discussion on the issues identified, then please drop us a message or give us a call. 

Details here: Contact Us 

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