Marine Engine Substantial Modification, NOx Tier Re-Certification & Retrofit Cost Tool
MARPOL Annex VI Reg. 13 • NOx Technical Code 2008 • MEPC.398(83) In Force 1 Sep 2026 • Tier I / II / III • EIAPP • SCR / EGR
Marine Engine Substantial Modification, NOx Tier Re-Certification & Retrofit Cost Tool
Screen whether an installed-engine project stays within routine Technical File maintenance or moves into a Regulation 13 major-conversion / re-certification path. Calculate the speed-dependent Tier limit, quantify the NOx gap and use Advanced for test-cycle weighting, section 7.2 onboard certification, Technical File readiness, retrofit integration and commercial cost.
↑Need much more depth? Click Advanced above.Advanced adds pre-2000 simplified-measurement logic, E2/E3/D2 cycle weighting, section 7.2 onboard test readiness, 85% test-power gate, SCR/EGR integration, reductant/fuel OPEX and certification CAPEX.
Fast10 primary inputs
Core answerTrigger + Tier gap + predicted compliance
2026MEPC.398(83) now in force
Engine Modification & Tier Gap Screen
The required Tier is entered deliberately. Tier III depends on the applicable NOx ECA and ship/engine date provisions; the calculator does not infer a Tier III obligation from geography alone.
kW.
kW.
rpm.
g/kWh.
% weighted reduction.
Regulation 13 & Certification Basis
Major conversion: Regulation 13.2 separately captures engine replacement/addition, substantial modification, and an MCR increase greater than 10% versus original certification. A routine Technical File replacement that does not alter emission characteristics is not substantial modification.
Rating, Speed & NOx Limit
g/kWh. 0 uses the cycle register.
Advanced NOx Test-Cycle Register
| Point | Power % | Weight | Baseline NOx | Reduction % | Post NOx | Weighted |
|---|
1 September 2026 Section 7.2 Onboard Test
% rated. Section 7.2 floor: 85% under agreed plan.
Retrofit Integration & Annual OPEX
mbar.
mbar.
g/kWh.
% (+ penalty, - saving).
Retrofit, Testing & Re-Certification CAPEX
2026 Re-Certification Readiness
Regulatory / engineering screening only: this tool cannot make the Administration's legal determination that a modification is substantial, establish Tier III ECA applicability, issue an EIAPP certificate, approve an Engine Emission test plan, certify an SCR/EGR installation or replace the approved NOx Technical File.
Current 2026 basis: MARPOL Annex VI regulation 13 applies to installed marine diesel engines over 130 kW except engines used solely for emergency purposes. Major conversion includes engine replacement/addition, substantial modification under the NOx Technical Code, or an MCR increase greater than 10% versus original certification. MEPC.398(83) entered into force on 1 September 2026 and adds section 7.2 for installed engines subject to substantial modification or certification to a Tier not held at installation. Section 7.2 permits Individual Engine or Engine Group certification, not Engine Family certification; requires an Administration-agreed Engine Emission test plan; requires a replacement nameplate when substantial modification changes rated power and/or speed; and permits the nominal 100% test point to be no lower than 85% of rated power under the agreed plan. MEPC.399(83) contains the 2025 SCR Guidelines and supersedes the 2017 SCR Guidelines.
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