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CaptainsGround
The receipts

Every answer traces to a primary source

We don’t generate facts from training data — we generate explanations from cited federal regulations and public-domain mariner texts. Here’s the corpus behind every lesson, drill, and flashcard.

2,069

Citations indexed

2,271

Source chunks

100%

Embedded

8

Primary sources

Live counts, refreshed hourly.

Every question → its source

Drill question

In a crossing situation, which vessel must keep out of the way?

COLREGs Rule 15

Rule 15 — Crossing situation

“…the vessel which has the other on her own starboard side shall keep out of the way and shall, if the circumstances of the case admit, avoid crossing ahead of the other vessel.”

In a lesson or drill, the chip is clickable — it opens the exact rule text inline.

Publishing principles

How an answer is published — and corrected

A fluent explanation is not enough. CaptainsGround keeps source retrieval, generation, validation, and correction as separate steps so an answer can be traced back to the rule that supports it.

01

Start with primary text

The generator receives retrieved chunks from 33/46 CFR, COLREGs, the Inland Rules, Bowditch, or USCG manuals. Each stored citation keeps the canonical source identifier.

02

Judge the finished artifact

A separate validator sees the answer and its source chunks, not the generator prompt. Drill questions that fail the source, answer, or ambiguity checks are not published.

03

Keep the citation resolvable

The citation audit checks that stored citations still resolve to corpus text. Source refreshes preserve older versions so an existing citation does not silently disappear.

Corrections stay traceable

If an answer and its cited rule disagree, email [email protected]. We check the source text, correct the artifact, and run it through validation again. The about page explains who operates the site and how to reach us.

Last updated: July 13, 2026

The corpus

Filter by source family. Everything here is federal regulation or public-domain text — verifiable, not paraphrased.

  • 33 CFR — Navigation and Navigable Waters

    CFR

    Inland Navigation Rules + USCG operating rules.

    602 chunks · 400 citations

    ecfr.gov · Title 33

    last ingested 2026-07-16

  • 46 CFR — Shipping

    CFR

    Subchapters T (small passenger vessels) and B (mariner credentialing).

    1,329 chunks · 1,329 citations

    ecfr.gov · Title 46

    last ingested 2026-07-28

  • COLREGs (72 COLREGS)

    Rules of the Road

    International Regulations for Preventing Collisions at Sea — 38 navigation Rules (Parts A–E) (annexes covered separately under 33 CFR).

    38 chunks · 38 citations

    IMO · public domain

    last ingested 2026-07-28

  • Inland Navigation Rules

    Rules of the Road

    Parallel set of rules for inland US waters; codified at 33 CFR Subchapter E.

    Indexed on next ingest

    33 CFR §83

  • Bowditch — American Practical Navigator

    Bowditch

    NGA. Public domain. Reference for celestial, dead reckoning, charts.

    41 chunks · 41 citations

    NGA Pub. 9

    last ingested 2026-07-28

  • USCG Boatswain's / Coxswain's Mate manuals

    USCG

    Public-domain US Coast Guard training texts.

    24 chunks · 24 citations

    USCG · public domain

    last ingested 2026-05-01

  • Light List & Buoy Chart Symbols

    USCG

    USCG Light List + Chart No. 1 buoy and aid symbols.

    75 chunks · 75 citations

    USCG · public domain

    last ingested 2026-05-01

  • ENGINE_MANUALS

    USCG

    162 chunks · 162 citations

    last ingested 2026-07-28

Sources · CaptainsGround