Methodology & Data Sources — How ArcNautical scores a vessel

Data sources

ArcNautical does not publish its own sanctions designations or detention records. It screens against, and cites, the authoritative public sources below — each lookup carries the source name and the date it was read.

Source	Used for	Refresh
OFAC SDN List U.S. Treasury, Office of Foreign Assets Control	Sanctions screening	Daily · search
EU Consolidated Financial Sanctions	Sanctions screening	Daily · map
UN Security Council Consolidated List	Sanctions screening	Daily · list
UK HMT / OFSI Consolidated List	Sanctions screening	Daily
OpenSanctions	Consolidated + vessel datasets	Daily · site
GLEIF Global LEI Index	Ownership chain & beneficial owner	24h cache · search
Paris MoU	Flag-state PSC performance (White/Grey/Black)	Annual list, WGB 2021–2023 · site
Tokyo MoU	Flag-state PSC performance	Annual list, 2023 · site
Equasis	PSC inspection & detention history	Per lookup · site
AIS	Position & port-call history	Continuous

Paris and Tokyo MoU White/Grey/Black placements were last reconciled against the published annual lists on 2026-05-30.

The sanctions verdict — RED / AMBER / INCOMPLETE / GREEN

The headline status answers one question: does this hull match a current sanctions listing?

RED

Confirmed match. The vessel's IMO or MMSI exactly matches a sanctions-list entry, or another high-confidence identifier match is present. The matched list and entry are shown.

AMBER

Potential match — low confidence. At least one name or fuzzy match exists that is not identity-confirmed. AMBER is a prompt to verify, never a conclusion.

INCOMPLETE

Could not be attested as clear. A core sanctions source was unreachable, the screen itself failed, or the vessel's identity could not be resolved from the IMO. The engine fails closed: rather than show a reassuring GREEN it cannot defend, it reports INCOMPLETE. This is not a clearance — re-screen before acting.

GREEN

No matches across the comprehensive sanctions sources, which all loaded at the time of screening. We name only the lists actually reached — if one was unavailable the verdict is INCOMPLETE (or, for a supplementary source, GREEN with the gap disclosed), never a GREEN that attests a check that did not run.

Match confidence is ranked exact IMO → exact MMSI → name + flag → fuzzy name. Only an exact identifier (or otherwise high-confidence) match produces RED; everything weaker is AMBER and flagged for human review.

Ownership opacity — 0 to 100

Opacity measures how hard it is to see who actually controls a vessel. 0 is fully transparent; 100 is opaque. The score is driven by how far the corporate chain resolves in the GLEIF LEI index, whether the registered owner sits in a shell-company jurisdiction, and whether a beneficial owner is disclosed.

LOW

0–30. Registered entity and parent chain resolvable in GLEIF.

MEDIUM

31–60. Partial resolution — some chain or owner detail missing.

HIGH

61–100. No GLEIF record and/or registration in a shell-company jurisdiction with no beneficial-owner disclosure.

Shell-company jurisdictions weighted toward opacity

MH · PA · LR · VG · KY · BM · GI · IM · JE · GG · BS · SC · MU · CW · AG · WS · VU · KM · TO

The vetting grade — A to E

The vetting grade is a single weighted composite (0–100, where lower is better) mapped to a letter. It blends five independent risk signals:

30%

Detention history (PSC)

25%

Flag-state performance

20%

Ownership opacity

15%

Vessel age

10%

Inspection gap

0–20

21–40

41–60

61–80

81–100

Three things we do deliberately, and disclose:

A confirmed sanctions match floors the grade to E, regardless of the underlying feature scores. A sanctioned hull is never graded "moderate".
When Port-State-Control data is unavailable, the detention weight is redistributed to the remaining signals — we do not invent a detention score to fill the gap.
Only signals backed by real data contribute to the average (active-signal weighting). A missing signal is excluded, not silently scored zero.

Freshness

Sanctions and inspection data change constantly. Every baked figure on a vessel, flag, or entity page carries the snapshot date it was read. For a current answer, the free /check tool re-screens the vessel against the live lists at the moment you query it.

Limitations & responsible use

ArcNautical is a decision-support tool, not legal advice, and not a substitute for OFAC's own SDN search or a licensed compliance / KYC programme.
An AMBER / "potential" match is not a confirmation. Verify the underlying identity before taking or refusing any action.
Sanctions lists change daily; PSC and ownership data change frequently. Always confirm against the primary source on the date of your decision.
When an upstream source is temporarily unreachable, ArcNautical shows what it has plus the as-of date — a missing signal is disclosed, never fabricated.

Who builds this

ArcNautical is independent maritime intelligence, not affiliated with any sanctions authority, flag registry, or classification society. Questions about a specific result or the methodology are welcome at [email protected].