Wheelhouse Prep USCG Mariner Exam Prep

Master < 100 GRT to Master or Mate < 200 GRT Rivers, Revision & Practice Exams

Master < 100 GRT to Master or Mate < 200 GRT Rivers. Built from official USCG NMC sample examinations (public domain).
Content last updated 12 June 2026

Revision Mode

Revise with instant feedback: the moment you pick an answer you see whether it was right, with the explanation where available. Untimed — ideal before you sit a mock exam. Questions you miss keep coming back until you know them.

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Exam Mode

Exam-day conditions: no feedback until you submit, each module scored separately so you can see your weak areas, plus an overall score against the pass mark, with a full question-by-question review at the end.

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The real exam is passed module by module: Rules of the Road requires 90%, most other modules 70%. Chart-plotting modules are taken on paper and not included.

Modules & your progress

Unlock the full question bank

The free sample is 12 questions, spread across every module in the same proportions as the real exam. The full bank contains every question from the NMC's current published sample examinations for this credential, with written explanations on the popular small-vessel credentials, one-off $29, lifetime access on up to 3 devices, all credentials included.

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Score history

The real exam: key facts

Delivered byUS Coast Guard National Maritime Center; exams are sat at Coast Guard Regional Exam Centers (RECs)
Official examMerchant Mariner Credential (MMC) endorsement examinations
QuestionsSet per credential in your Approval to Test letter; the NMC does not publish module question counts
TimeEach module is sat in a 3½-hour examination period; modules are taken in consecutive periods
Passing scoreRules of the Road 90%; Deck General and Deck Safety 70% (NMC notice, January 2018)
Exam feeSet by 46 CFR 10.219: for an original officer endorsement, evaluation $100, examination $95 (lower level) or $110 (upper level), issuance $45
Pre-licensing or eligibilityApply to the Coast Guard first; you need the NMC's Approval to Test letter before you can book. The application stays valid for 12 months
Book your examdco.uscg.mil/nmc/Examinations

Checked 11 October 2026 from the official sources below. Rules and fees change, so confirm with US Coast Guard National Maritime Center; exams are sat at Coast Guard Regional Exam Centers (RECs) before you book.

Official sources

How Wheelhouse Prep compares

Wheelhouse is a $29 question bank built from the Coast Guard's own sample exams, not an approved course. Here is how it compares with the courses and tools mariners usually consider, including where they are the better choice. See the comparison with Mariners Learning System, Sea School, MPT and others.

Frequently asked questions

What score do I need to pass the Master < 100 GRT to Master or Mate < 200 GRT Rivers exam?

You must pass each module separately. Most modules require 70% to pass.

What modules are on the Master < 100 GRT to Master or Mate < 200 GRT Rivers exam?

The exam covers 1 module: Navigation and Deck General – Safety.

How many practice questions are available for Master < 100 GRT to Master or Mate < 200 GRT Rivers?

This page includes free sample questions drawn from the official USCG sample examinations, with a full bank of around 50 questions across all modules available with lifetime access.

Are these real USCG exam questions?

Every question comes from the U.S. Coast Guard National Maritime Center's published sample examinations, which are U.S. government works in the public domain. Wheelhouse Prep is not affiliated with or endorsed by the U.S. Coast Guard.

Do I need to create an account?

No. The free practice tests work in your browser with no signup. Your score history is saved on your own device.

When were these Master < 100 GRT to Master or Mate < 200 GRT Rivers questions last updated?

Last updated 12 June 2026. The bank is refreshed whenever the Coast Guard publishes revised sample examinations.

Sample Master < 100 GRT to Master or Mate < 200 GRT Rivers practice questions

A selection of free questions from the official USCG sample examinations. Use the interactive modules above for timed, scored drills.

Which agency publishes the Light Lists?

  1. United States Coast Guard ✓
  2. National Ocean Service
  3. Oceanographic Office
  4. Army Corps of Engineers

On an inspected vessel, when may a stability test be dispensed with?

  1. Coast Guard does not have a qualified inspector available
  2. Coast Guard has the approved stability test results of a sister vessel ✓
  3. The projected cost is unreasonable
  4. The vessel is of a proven design

Which of the signals listed is required to be displayed at night while bunkering at a dock?

  1. One red light over a white light
  2. Two red lights
  3. One red light ✓
  4. One red light over a yellow light
Show all 12 sample questions with answers

In plugging submerged holes, why are rags, wedges, and other materials used in conjunction with plugs?

  1. To reduce the possibility of stress fractures
  2. To reduce the water pressure on the hull
  3. To prevent progressive flooding
  4. To reduce the water leaking around the plugs ✓

Fog forms when the air temperature is at or below __________.

  1. 32°F
  2. the wet bulb temperature
  3. the dry bulb temperature
  4. the dew point ✓

When observing a rapid rise in barometric pressure, what may you expect?

  1. Clearing weather, possibly accompanied by high winds ✓
  2. Heavy rain or severe thundershowers
  3. Clear weather with no wind, but the possibility of rain or snow within 24 hours
  4. Deteriorating weather with rain or snow

Sweat damage in a hatch full of canned goods in cartons will occur when which condition exists?

  1. When the air temperature is lower than the temperature of the cargo
  2. When the air temperature is higher than the temperature of the cargo
  3. When the dew point is higher than the temperature of the cargo ✓
  4. When the dew point is lower than the temperature of the cargo

Which statement is TRUE concerning the life buoy on your small passenger vessel? (Length 28 feet)

  1. The life buoy(s) must be readily accessible ✓
  2. The life buoy(s) must be tied securely to the vessel
  3. Life buoys are not required to be fitted with lifelines
  4. All life buoy(s) must be orange in color

If your vessel is equipped with inflatable liferafts, how should they be maintained?

  1. Have them serviced by the shipyard annually.
  2. Have your crew check them annually.
  3. They do not need any maintenance.
  4. Have them sent ashore to an approved maintenance facility annually. ✓

The galley on your cargo vessel has an area of 2,900 square feet. What will fulfill the requirements for fire protection?

  1. One B-I extinguisher or post 2017 One 10-B:C extinguisher
  2. One B-II extinguisher or post 2017 One 40-B:C extinguisher
  3. One B-II and one C-II extinguisher or post 2017 Two 40-B:C extinguishers ✓
  4. One B-V extinguisher or post 2017 One 160-B extinguisher

On a clear, warm day, you notice the approach of a tall cumulus cloud. The cloud top has hard well defined edges and rain is falling from the dark lower edge. What should you expect if this cloud passes directly overhead?

  1. A sudden increase in wind speed ✓
  2. The wind speed will not change as it passes
  3. A sudden decrease in wind speed
  4. The wind will back as it passes

It is the responsibility of the crane operator to, at all times, be aware of the location of the __________.

  1. load
  2. hook
  3. boom
  4. All of the above ✓