Leading Maritime App - Since 2013

Seabook is an information and knowledge source for marine professionals, sailors as well as sea enthusiasts.

Seabook Master offers comprehensive and enriched content with computational tools. It is the leading #1 Maritime app that covers multiple subjects on the maritime profession. Seabook Master is ad-free with enriched content and powerful tools!

Seabook continues with regular updates to support maritime education and training as well as onboard usage with offline access.


COLREG Marine Meteorology Ship Stability Navigation Maritime English GMDSS Personal & Shipboard Safety Health & First Aid Marine Engineering Ropework Signal Flags Ship Management Chartering Maritime Business Country Flags Computation & Convertion Tools


Version Apple iOS Google Android OS
Other Systems
Seabook Master


All versions Seabook Master

Rules of the Road Sound Signals Lights & Shapes Rules for Priority Simplified Rules in Text COLREG Full Verison in Text

Clouds Wind Barb Beaufort Scale Temperatures Fronts Isobars Buys Ballot's Law Coriolis Effect Atmospheric Circulation Intertropical Convergence Zone Global Wind Patterns

Definitions Dangerous Goods - HazMat Draft Survey Transverse Stability Longitudinal Stability Dry-Docking and Grounding Draft Trim List Free Surface Effect/Moment Simpson's Rules GM Conditions Turning Circle Inclining Experiment Wind Heeling Moment Loadline Miscellaneous Carriage of Chemicals by Ships

Celestial Defitinions Compass Error Time / Arc Nautical Time IALA Hour Angles Twilight Intercept Great Circle Distance via Sextant Tide Speed Miscellaneous

Workshop tools SMCP Bosun's Store Oil Spill Kit Fire Safety Personal Safety Parts of Vessel Stability Construction Engine Parts Weather Bridge Equipments Galley

Sea Areas MSI - Maritime Safety Information MMSI Navtex Navtex Format Radio Frequencies Satellite Services VHF Channels MF/HF Radio Q Codes Digital Selective Calling NAVAREA WWNWS METAREA EGC - Enhanced Group Call Call Sign Prefixes Inmarsat Service Codes Inmarsat-C NDN Failure Codes

Personal Protective Equipment Life Saving Appliances Fire Fighting Safety Meeting & Toolbox ISM Code Risk Assessment Search and Rescue Operations Piracy at Sea

First Aid Recovery Position Medicines Hypothermia Shock Burns STD Coronavirus (COVID-19) Mental Health & Best Practices

Symbols Abbreviations Marine Pipe System (Color Codes) Valves Pumps MARPOL & Annexes MARPOL - Special Areas OWS - Oily Water Separator ORB - Oil Record Book Sewage Air Pollution ECAs - Emission Control Areas EEDI - Energy Efficiency Design Index Carriage of Chemicals by Ships

Knots Blackwall Hitch Cleat Hitch Figure-eight Knot Bowline Double Bowline Reef Knot Half Hitch Clove Hitch Boom Hitch Anchor Bend Barrel Hitch Heaving Line Bend Hitching Tie Carrick Bend Ground-Line Hitch Buntline Hitch Sheet Bend Rolling Hitch Sheepshank Gripping Sailor's Hitch Ossel Hitch Mooring Splicing

Signals At Sea Flag Codes

Chartering Abbreviations Port State Control PSC (Deficiency Codes) INCOTERMS Laytime Demmurage Despatch Laycan Charterparty Hague-Visby Rules York Antwerp Rules MARPOL & Annexes MARPOL - Special Areas

Easy to search Easy to identify

Temperature Converter Weight Converter Length Converter Speed Converter Pressure Converter Volume Converter Aries & Sun Nautical Almanac Sight Reduction Calculator Rhumb Line Calculator Great Circle Calculator Dead Reckoning Estimator Apparent Wind to Real Wind Real Wind to Apparent Wind CPA - Closest Point of Approach Calculator

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Version Download Provider
Seabook 3.0 (iOS)   Download   Apple Store
Seabook 3.1 (Android)   Download   Google PlayStore
Seabook Master 1.0 (iOS)   Download   Apple Store
Seabook Master 1.1 (Android)   Download   Google PlayStore
Seabook 3.0 (API Level 19) - (Min. Android v. 4.4)   Download   HTTP direct download
Seabook 3.0 (Vietnamese Review)   Download
Seabook 1.1 (BlackBerry)   Download   Opera/Bemobi Store
Seabook 1.1 (Nokia - SymbianOS)   Download   Opera/Bemobi Store
Seabook 1.1 (WebOS)   Download   HTTP direct download
Seabook 1.1 (Windows Mobile)   Download   Opera/Bemobi Store
Seabook 1.1 Windows Desktop (Self Executable File)   Download   HTTP direct download


Captain Ozgur Dogan Gunes

Ozgur Dogan Gunes is a maritime professional, as a Master Mariner, with vast experience both onboard the various types of vessels and onshore at the senior management level. He has worked at High-Risk Piracy Areas at sea and worked onshore across the three continents with sound leadership and management.

Captain Ozgur commissioned in maritime organizations for the further development of the industry. He has authored books and implemented software solutions spanning the industry towards digitalization.

He continues to push at the forefront of maritime practices challenging on Human Element, Training, Safety, Quality, and Digitalization with Cybersecurity.

Reach and follow him on social media


Please visit for details. Thank you!


Please write to Ahoy @ Thank you!


  • Version 1.0. First Release for iOS and Android
  • Version 1.1. Included Windows Phones and Smart Televisions
  • Revision 1.2. Updated Contents
  • Revision 1.3. Included PC/Windows & Linux Compability
  • Version 2.0. Core Update Android SDK
  • Revision 2.1. Updated Contents
  • Revision 2.2. Updated Contents, Minor Bug Fixes for new systems
  • Revision 2.3. Updated Android SDK for better UI and new devices
  • Revision 2.4. Updated in contents and improvement for all devices
  • Revision 3.0. Minor updates in contents, AdMob utilization.
  • Revision 3.0.1 Minor updates in contents, removed AdMob utilization.
  • Seabook Version 3.1.0. New subjects, enriched content with Maritime English, SMCP, and Port State Control
  • Master Version 1.0.0. New subjects, enriched content with powerful tools and converters
  • Master Version 1.1.0. New subjects, enriched content with Maritime English, SMCP, and Port State Control
  • Disclaimer

    The information included at Seabook is for educational purposes only with practical access, and is not intended to be a substitute of official publications nor curriculums at institutions. The user should consult his or her supervisor onboard. Seabook holds no responsibility with the contents but authors put best efforts to support maritime education & training. Thank you for using Seabook with care!