The Cost of Waiting for Drydock Has Changed
Why owners and operators are reassessing what really needs to wait until the next scheduled docking.
By Constantinos Spyrou, Commercial Director, Servway
Not every underwater finding needs to wait for the next scheduled drydock. But that does not mean every finding requires immediate intervention either. The more useful question is whether waiting is still the right operational decision.
For owners and operators, that decision increasingly comes down to the vessel’s actual condition, the consequences of deferring the work and whether the issue can be addressed safely while the vessel remains afloat.
The cost of waiting
Every vessel reaches drydock eventually, for statutory surveys, major steel renewal, extensive coating work, and repairs that need full dry access. That hasn’t changed.
What has changed is the cost of waiting. “We’ll deal with it at the next drydock” used to be a reasonable default for a non-critical underwater finding. Today, that decision is increasingly assessed against fuel use, emissions performance, schedule and charter commitments, not just repair cost.
Biofouling is one of the clearest examples. Growth on the hull, propeller and other submerged surfaces increases hydrodynamic resistance and can increase the energy required to maintain vessel performance. That inefficiency now carries more direct operational, emissions and compliance consequences.
CII has been mandatory since 2023 for applicable vessels, linking annual operational carbon intensity to an A-to-E rating. EU ETS has also increased the cost exposure associated with emissions: methane and nitrous oxide entered the maritime ETS scope in 2026 alongside CO2, while emissions generated during 2026 are subject to the full phase-in of the scheme for ships within its scope. FuelEU Maritime, in force since 2025, separately sets requirements for the greenhouse-gas intensity of energy used onboard ships covered by the regulation. These measures do not operate in the same way, but together they reinforce the commercial importance of vessel efficiency and emissions performance.
A fixable underwater condition can therefore have consequences beyond the maintenance budget, affecting fuel consumption, emissions exposure, CII performance and operating margin. Waiting may still be the correct decision. It simply needs to be a considered one.
The framework around in-water intervention has developed
The framework around underwater hull maintenance has also evolved. In April 2025, the IMO issued dedicated guidance on in-water cleaning of ships’ biofouling, covering factors including the fouling condition, cleaning method, coating compatibility and the environmental risks associated with removing biofouling while a vessel remains in the water.
This does not mean that underwater cleaning is automatically appropriate in every case. The vessel’s condition, coating system, fouling level, location and applicable port or regulatory requirements all need to be considered before intervention.
From finding to action
A recent underwater job handled by Servway at Suez anchorage illustrates the decision in practice. A crude oil tanker was inspected and cleaned underwater, with propeller polishing also carried out. The initial inspection recorded moderate fouling across approximately 70% of the hull sides and propeller, increasing to around 90% on the rudder.
Servway managed and delivered the full scope of work, including hull cleaning, propeller polishing and underwater inspection. The work was completed within the same day while the vessel remained at Suez anchorage.
Following the work, the inspection found the hull, rudder, stern frame, bilge keels and flat bottom to be in good condition, with no visible structural damage identified in the areas inspected.
The case shows how early assessment and a fast operational response can turn a finding into action: Servway identified the extent of fouling and completed the required underwater work within the same day at anchorage.
What this means in practice
This is not an argument for underwater intervention over drydock as a rule. Major structural renewal, extensive coating replacement and repairs requiring full dry access still belong in drydock. What matters is the vessel’s actual condition: the consequences of deferring the issue, whether underwater inspection provides enough evidence to make a decision, and whether intervention can be carried out safely within the applicable technical, port and regulatory requirements.
Intervening simply because an underwater option exists, without establishing whether it’s necessary, is its own mistake. The value of assessing early is that waiting becomes a decision, backed by evidence, rather than a habit.
This article provides a general industry overview and does not constitute technical, regulatory or compliance advice. The application of CII, EU ETS and FuelEU Maritime requirements depends on the individual vessel and its operations, including factors such as vessel type, size, voyages and ports of call.
Sources
International Maritime Organization (IMO), Biofouling
International Maritime Organization (IMO), EEXI and CII – ship carbon intensity and rating system
European Commission, FAQ – Maritime transport in EU Emissions Trading System (ETS)
European Commission, Decarbonising maritime transport – FuelEU Maritime
International Maritime Organization (IMO), MEPC.1/Circ.918 – Guidance on in-water cleaning of ships’ biofouling
Sources
Source: International Maritime Organization (IMO), “Biofouling” — current overview of hydrodynamic, fuel-cost and emissions impacts; includes the 2023 Guidelines and MEPC.1/Circ.918. https://www.imo.org/en/ourwork/environment/pages/biofouling.aspx
Source: IMO, “EEXI and CII — ship carbon intensity and rating system.” https://www.imo.org/en/mediacentre/hottopics/pages/eexi-cii-faq.aspx
Source: European Commission, “FAQ — Maritime transport in EU Emissions Trading System (ETS).” https://climate.ec.europa.eu/eu-action/transport-decarbonisation/reducing-emissions-shipping-sector/faq-maritime-transport-eu-emissions-trading-system-ets_en
Source: European Commission, “Decarbonising maritime transport — FuelEU Maritime.” https://transport.ec.europa.eu/transport-modes/maritime/decarbonising-maritime-transport-fueleu-maritime_en
Source: IMO, MEPC.1/Circ.918, “Guidance on in-water cleaning of ships’ biofouling.” Approved at MEPC 83, April 2025. https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/Biofouling%20pages/MEPC.1-Circ.918%20-%20Guidance%20On%20In-Water%20Cleaning%20Of%20Ships%27%20Biofouling%20%28Secretariat%29.pdf
Source: Lloyd’s Register, Class News 02/2025, “New Categories of Service Suppliers,” 21 January 2025. https://www.lr.org/en/knowledge/class-news/02-25/
Source: DNV, “Bottom survey — In-water.” https://www.dnv.com/services/bottom-survey-in-water/
Source: American Bureau of Shipping (ABS), “ABS Notations and Symbols” — UWILD notation and conditions. https://ww2.eagle.org/content/dam/eagle/rules-and-guides/current/generic/list_of_ABS_notations_and_symbols/class-notations-table-mar25.pdf