CBDR

New in 1.4: Tides & Currents — live NOAA and CHS station predictions kept for offline use, and teaching pages where the water actually moves. The Moon's tides, in 3D.

CBDR helps to train junior deck officers in vital mariner skills. Named for constant bearing, decreasing range, the term CBDR should grab any mariner's attention, and this app is built to help develop the knowledge necessary to act IAW COLREGS while at sea, along with other mariner skills.

RADAR & CONTACT REPORTS. Live scenarios on a real radar scope — north-up or course-up, relative or true vectors, trails, CPA markers. Classify the situation under the Rules, order the maneuver, and give the contact report the way it should be given. Multi-contact pictures are assessed whole, the way a bridge team has to. Speak your report and the app grades it, or type it. Every recommendation cites the Rule it stands on, and "How CBDR Decides" shows the logic in full — no black boxes.

MANEUVERING BOARD. Nine Pub 1310 problem types with step-by-step worked constructions: CPA, avoidance, stationing, two-step stationing, limiting range, bearings-only TMA, fictitious ship, advance and transfer, true and desired wind. Bring your own numbers and run them through the same walkthroughs.

OOD MATH. The arithmetic a watch runs on, worked in the head and on paper: minute rules (mental only — the app says so), time-speed- distance, TVMDC compass conversion, Bowditch time zones, the 60-to-1 rule staged on replenishment approaches, visibility and raising lights, doubling the angle on the bow, and anchoring — chain in whole shots, swing and drag circles in yards.

RULES OF THE ROAD. The 954-question USCG bank, solo tests with immediate feedback, and every question linked to the governing Rule with the exact passage highlighted — verified verbatim against the Navigation Rules. Guided Practice learns which rules you miss and draws your sessions toward them; progress stays on your phone, and the algorithm that picks your questions is documented in the app.

TIDES & CURRENTS. Station predictions for the United States and Canada, found on a map, fetched from NOAA and CHS when you ask, and kept for offline use — tables, a curve you can put your finger on, and exports for Excel and PowerPoint. Beside the lookup, teaching pages where the water moves: the reversing current run as a transit of San Diego Bay, the rotary current turning through the compass offshore, the hydraulic current in the Cape Cod Canal — and How Tides Work, the Moon's pull drawn in three dimensions, from the uneven pull and the two bulges to springs, neaps, and what the chart datum means. Every arrow and bulge is computed from the physics, and the days are honestly invented.

NAVIGATION FUNDAMENTALS. Time zones with an interactive Bowditch zone map, ETA and speed-of-advance drills, and How Fixes Work — ten step-through teaching pages covering visual, radar, soundings, celestial, GPS (drawn in three dimensions, because the fourth satellite is what pins your altitude), running fix, dead reckoning, and set and drift. Never graded. They exist to teach.

CHART NO. 1 ABOARD. Every symbol, abbreviation and term, reorganized by chapter and section, searchable offline, with the printed plates.

CLASSROOM. Host a group exam by QR code — no server, no network. Results return by QR with per-question rubrics, and the record exports as a signable PDF roster or CSV.

Everything runs offline. No account, no data collection — what you practice stays on your device, and deleting the app deletes it.

Built with from experience, and checked against The American Practical Navigator, COLREGS, and Farwell's.