Sea and seamanship
Maritime tools that run in your browser: a COLREG lights and shapes trainer, a light characteristic decoder, offline tide predictions, compass error from the sun, a maneuvering board with CPA and TCPA, seafarer rest-hour records and port-to-port passage planning.
Ship lights under COLREG-72
Vessel lights, day shapes and sound signals under COLREG-72: identify ships from any aspect by night and day, take an exam, see the rule. Online.
Light characteristic
Paste a chart abbreviation — Fl(3)WR.15s12M — and get it decoded, the rhythm played live, and the range of first sighting. Plus IALA buoyage.
Compass error
Compass error from the azimuth of the Sun, Moon and stars, amplitude, a deviation table from A–E coefficients and course conversion. Ship's time.
Marine coordinates
Degrees and minutes, DMS, UTM, MGRS from any entry. Rhumb line and great circle between points, GPX export and a phonetic readout for VHF.
Seafarer hours of work and rest
Seafarer hours of rest record under STCW and MLC: 10 h in any 24 h, 77 h in any 7 days, rolling windows, breaches and a form to sign.
Maneuvering board
Two radar plots give the target's course, speed, CPA and TCPA with an honest error bound. Trial maneuver and exercises with answers.
Anchoring and anchor watch
Rode length from the depth at high water, swinging circle, chain catenary — and a GPS drag alarm that runs in the browser.
Sea distance between ports
A route over water between any two ports: nautical miles, passage time, fuel. Computed in your browser, with canal options and no limits.
Tide Times
High and low water times for any coastal place, a tide curve two weeks ahead and under-keel clearance. Computed in your browser, works offline.
Small-craft skipper practice test
The official EMERCOM question list — 1,221 questions with answers by vessel type and navigation area, plus a ticket in the order No. 90 format.
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