Rules of the Road: No exceptions to limits on sulfur

Oct 8, 2019 by Capt. Jake DesVergers

Rules of the Road: Capt. Jake DesVergers

There are lots of priorities in yachting: food, drinks, carpets, air conditioning, toys, cleaning supplies – the list is endless and subjective to the particular person involved. These priorities depend upon the owner, charter guests, captain and crew. And they can change daily or every few minutes.

However, a universal need for every vessel – yes, even for sailboats – is fuel. It must be of sufficient quantity and quality. 

For merchant ships, the main type of “bunker” is heavy fuel oil (HFO). It is derived as a residue from crude oil distillation. Crude oil contains sulphur,  which, following combustion in the engine, ends up in the ship’s emissions. It goes out the stack and into the air.

For yachts, the primary fuel oil is marine diesel. Some larger yachts use intermediate fuels and various blends.

The International Maritime Organization (IMO) established regulations to reduce sulphur oxide, or SOx, emissions from ships. They first came into force in 2005 under Annex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL). Since then, the limits on SOx have been progressively tightened.

SOx are present in marine fuels. They are known to be harmful to human health and a proven cause of respiratory symptoms and lung disease. In the atmosphere, SOx can create various problems, including acid rain. Its effects can harm crops, forests and aquatic species. This toxic rain also contributes to the acidification of the oceans. Limiting SOx emissions from all vessels, including yachts, will improve air quality and protect the environment.

Starting on Jan. 1, 2020, the limit for sulphur in fuel oil used on board all vessels will be reduced from the current 3.5% to 0.5% m/m (mass by mass). This will significantly reduce the amount of SOx emissions emanating from ships. It should also have major health and environmental benefits for the world, particularly for populations living close to ports and coasts. This new regulation is commonly referred to as “IMO 2020.”

For those vessels operating in an IMO-established Emission Control Area (ECA), there is a further reduced limit for SOx content. It is currently set at 0.1%. The ECA locations are the Baltic Sea; the North Sea; the North American area, which comprises coastal areas off the United States and Canada; and the United States Caribbean Sea area, which comprises Puerto Rico and the Virgin Islands. Countries surrounding the Mediterranean Sea are in discussion to designate that area, or a part thereof, as an ECA. Fuel oil suppliers in these ECAs already deliver products that meet the 0.1% limit. Examples are marine distillate and ultra-low sulphur fuel oil blends.

Now, does IMO 2020 only apply to commercial vessels? No, the MARPOL regulations apply to all ships and yachts – everything on the water. From a certification viewpoint, only ships and yachts of 400 gross tonnage and above must possess an International Air Pollution Prevention (IAPP) Certificate. 

With IMO 2020 in place, what must a ship or yacht do to comply? MARPOL regulations limit the sulphur content in fuel oil. This means that ships and yachts need to use fuel which is low in sulphur. In an effort to achieve a compliant fuel and maintain sufficient worldwide supplies, refineries may blend fuel oil with a high (noncompliant) sulphur content with fuel oil that has a lower content than the required threshold. The new combination would be below the required level. Additives may also be included to enhance other properties, such as lubrication.

On some ships and larger yachts, the vessels will limit the air pollutants by installing exhaust gas cleaning systems, also known as “scrubbers.” This is an accepted alternative method to meet the sulphur limit requirement. These scrubbers are designed to remove SOx from the ship’s engine and exhaust gases.

Many newer ships and yachts are being built with engines that can use alternative fuels. This includes biofuels and liquified natural gas (LNG). There is also an initiative to design completely electric propulsion.

As with every new regulation, the question is raised: Is that date set in stone? Yes, it is confirmed. There can be no change to the Jan. 1, 2020,  implementation date, as it is too late for any amendments or revisions to be approved for postponement. Be ready.

Capt. Jake DesVergers is chief surveyor for International Yacht Bureau ( Comments are welcome below.


About Capt. Jake DesVergers

Capt. Jake DesVergers is chief surveyor for International Yacht Bureau (IYB), an organization that provides flag-state inspection services to yachts on behalf of several administrations. A deck officer graduate of the U.S. Merchant Marine Academy at Kings Point, he previously sailed as master on merchant ships, acted as designated person for a shipping company, and served as regional manager for an international classification society. Contact him at +1 954-596-2728 or

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