Welcome to Seasources.net. Established in 1996, we are the ultimate source for online USCG exam preparation assistance. Seasources.net provides free online exam preparation along with downloadable studyguides and standalone software that allows you to continue your studies without an internet connection.

The first SeaSources.net, Training for Mariners. The First with Online Study for the Maritime Industry.

Click here to create an account in the online study and begin your license preparation.

The subjects listed below are currently available for testing in the new online study room and are available for download to your computer. Click on subject below for details.

Engineering Examination Questions

All Engine Room Questions

Engine Room Electrical         

Engine Room General          

Engine Room Safety            

Engine Room Steam            

Engine Room Motor   

Gas Turbine Plants 

QMED Oiler          

Deck Examination Questions

Master 25/50/100 Ton

Operator Uninspected Passenger Vessel

All Deck Exam Modules

Able Seaman Questions

Advanced Subjects, Unlimited Oceans Master, Mate

Rules of the Road  

Aids to Navigation  Glossary Included

Breathing Apparatus

Cargo Equipment 

Cargo Stowage

Charts and Publications 

Chemical Testing

Right Whales

Damage Control  

Deck Engineering

Deck Safety

Emergency Procedures 

FCC Exam Questions

Fire Fighting Glossary Included 

First Aid  


Great Lakes

Hazardous Cargo

Inert Gas

Inland Navigation  

Instruments and Accessories



Liquid Cargo and Bunkering

Marine Radio Operator 

Meteorology  "Glossary Included" 

Mobile Offshore Drilling Unit

Previews of Deck and Engine Room Questions

Celestial Navigation

Navigational Procedures

Pollution Control and Prevention

Rules and Regulations

Plotting/Navigational Problems


Survival Craft

Seamanship   Glossary Included

Sailing Vessels  

Ship Handling 

Ships Construction Glossary Included  

Ships Business


Stability and Trim Glossary Included 


Tides and Currents Glossary Included 



Common Knots

Radar Plotting

Master 25/50/100 Ton

 Inland/Near Coastal/Great Lakes License

We now have a whole new website.


Click here to redirect. 

License Requirements:

  The USCG Master License allows the holder to operate inspected vessels as well as undisputed vessels. Any vessel that is certified (authorized) by the USCG to carry more than 6 paying passengers plus crew must have a Captain who holds a 25/50/100 Ton Master license. Ferry boats, harbor tours boats, whale watch boats are examples of inspected vessels.

  There are 4 different Master Licenses a mariner may qualify for such as the Master Inland or Master Near Coastal. Both the amount of sea service time and the size vessels you have been on will influence the license you are eligible for. Master licenses are tonnage rated at 25 GT (gross tons), 50 GT, or 100 GT. The tonnage you are awarded is determined by the size vessels you've gained experience on in the last 3 years - it's called "recency experience." You are not required to advance through the different licenses one at a time. If you meet the USCG requirements for the master 100GT Near Coastal, you'll get that license as your first license. The 4 types of up to 100GT Master licenses are listed below along with the requirements:

  1. Master Inland: 360 days underway experience since age 15; 90 of those 360 days in the last 3 years. Completion of approved Course and Test.
  2. Master Inland/OUPV: 360 days underway experience since age 15; 90 of those 360 days in the last 3 years; 90 of those 360 days outside the boundary lines.
  3. Master Inland/Mate N.C.: 360 days underway experience since age 15; 90 days of those 360 days in the last 3 years; 180 of those 360 days outside the boundary lines.
  4. Master Near Coastal: 720 days underway experience since age 15; 90 of those 720 days in the last 3 years; 360 of those 720 days outside the boundary lines.

The following modules are currently in the online study.

  • GLI01 Master, Great Lakes and Inland, Unlimited Tonnage Q100, Q300, Q302, Q303, Q304, Q305, Q306.

  • GLI02 Mate, Great Lakes and Inland, Unlimited Tonnage Q100, Q300, Q308, Q309, Q310, Q311, Q312.

  • GLI03 Master, Great Lakes and Inland, LT 500-1600 GRT. Q100, Q300, Q320, Q321, Q322, Q323, Q324, Q326.

  • GLI04 Mate of LT 500-1600 GRT Q100, Q327, Q328, Q329, Q330, Q331.

  • GLI05 Master or Mate of LT 200 GRT Q100, Q300, Q340, Q341, Q342, Q343, Q345, Q346.

  • GLI06 Master or Mate of LT 100 GRT Q100, Q347, Q348, Q349, Q350, Q352.

  • GLI07 OUPV Q100, Q300, Q356, Q357, Q358.

  • GLI08 Limited OUPV Q301, Q360, Q361.

Additional Requirements:

  • Transportation Workers Identification Credential (TWIC)
  • Minimum age: 19 years old
  • A physical exam if more than three years has elapsed since the last exam
  • Drug test unless enrolled in a USCG-required random drug program for at least 60 of the last 185 days, and with no failure or refusal to participate in a chemical test for dangerous drugs
  • CPR/First Aid Card
  • U.S. Citizenship
  • Character reference letters
  • Completed USCG application package


Testing Requirements: Available in the Online Study

Navigation Rules of the Road:

  • Part A - General
  • Section I - Conduct of Vessels in Any Condition of Visibility
  • Section II - Conduct of Vessels in Any Condition of Visibility
  • Section III - Conduct of Vessels in Restricted Visibility
  • Part C - Light s and Shapes
  • Part D - Sound and Light Signals
  • Differences between International and U.S. Inland Rules of the Road

Deck Safety:

  • Fire Fighting
  • Marine Engine Operations
  • Marine Radiotelephone
  • Lifesaving Equipment
  • Pollution Prevention

Deck General:

  • Basic Seamanship
  • Characteristics of Weather systems
  • Ship Handling
  • Emergency Procedures
  • Maritime Law

Piloting and General Navigation:

  • Piloting
  • Compasses
  • Plotting
  • Tides and Currents
  • Approaches to Anchorages and Harbors
  • Electronic Navigation Equipment


  • Purchases, Blocks and Tackle
  • Vessel Handling in Rivers and Estuaries
  • Dragging, Clearing Fouled Anchors
  • Maneuvering for Launching of Lifeboats And Lifeboats in Heavy Weather
  • Receiving Survivors from Lifeboats
  • Towing Operations

Vessel Characteristics:

  • Principles of Ship Construction
  • Trim and Stability

Fire Prevention and Firefighting Appliances:

  • Fire Prevention and Chemistry of Fire
  • Basic Fire Fighting - Extinguishing Agents
  • Organization of Fire Drills
  • Fire Fighting Systems
  • Fire Fighting Equipment and Regulations for T-Boats

Ships Business:

  • Rules and Regulations for T-Boats
  • Shipment, Discharge and Manning
  • Certificates and Documents Required
  • Load Lines

Shipboard Management and Training:

  • Ship Sanitation
  • Principles of Damage Control Including Vessel Alteration and Repair
  • Shipboard Safety Management


  • Survival at Sea
  • Lifesaving Appliance Regulations and Operations for T-Boats

Plotting Tools Needed:

  • Long Island Sound Training Chart -12354TR
  • Dividers
  • Nautical parallel rule
  • Calculator
  • Pencils
  • Erasers

Reference Aids:

  • Publication No. 102
  • Publication No. 117 - Radio
  • Reprints from the Light Lists and Coast Pilots: Included in online study
  • Reprints from the Tide Tables: Included in online study
  • Chart No. 1
  • Merchant Mariner Deck Examination Illustrations: Included in online study
  • Title 46 Shipping - United States Code Annotated
  • Title 33, CFR

If you are studying for a United States Coast Guard Deck License exam which includes this module, you should  work through these questions until you are scoring 80% or better on them.

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SeaSources.net, Training for Mariners, is a registered Trademark

Copyright 2000 by SeaSources.net. All rights reserved.
Revised: 26 Oct 2023 13:52:08 -0400 

Contact Phone: 207-629-7004

Email: Captain Steve 

  For details on license requirements, application forms,  licensing fees, and testing locations, visit the United States Coast Guard / National Maritime Centers web site and look under Mariner's information center. The questions used in the online study  are updated annually from the NMC sample exams. All illustrations are current.

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See also:

SeaSources online Celestial Navigation Course 

MARYLAND NAUTICAL  Great source for practice charts and study guides


National Oceanic & Atmospheric Administration (NOAA)

Chart No. 1 Nautical Chart Symbols Abbreviations and Terms

Bluewater Books and Charts 

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