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.
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.
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.
The free sample is 101 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.
| Delivered by | US Coast Guard National Maritime Center; exams are sat at Coast Guard Regional Exam Centers (RECs) |
|---|---|
| Official exam | Merchant Mariner Credential (MMC) endorsement examinations |
| Questions | Set per credential in your Approval to Test letter; the NMC does not publish module question counts |
| Time | Each module is sat in a 3½-hour examination period; modules are taken in consecutive periods |
| Passing score | Rules of the Road 90%; Deck General and Deck Safety 70% (NMC notice, January 2018) |
| Exam fee | Set 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 eligibility | Apply 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 exam | dco.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.
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.
MODU stands for Mobile Offshore Drilling Unit.
You must pass each module separately. Most modules require 70% to pass.
The exam covers 10 modules: OIM – Deck General – Safety, OIM Unrestricted, OIM Surface Units Underway, OIM Surface Units on Location, OIM Bottom Bearing Units Underway, OIM Bottom Bearing Units on Location, Barge Supervisor – Deck General – Safety, Barge Supervisor – MODU Operations, BCO – Deck General – Safety, BCO – MODU Operations.
This page includes free sample questions drawn from the official USCG sample examinations, with a full bank of around 499 questions across all modules available with lifetime access.
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.
No. The free practice tests work in your browser with no signup. Your score history is saved on your own device.
Last updated 12 June 2026. The bank is refreshed whenever the Coast Guard publishes revised sample examinations.
A selection of free questions from the official USCG sample examinations. Use the interactive modules above for timed, scored drills.
Where there are multiple accident victims, which type of injury should be the first to receive emergency treatment?
Which is TRUE of a distress signal?
Which term(s) are in the category of "oil" as used in the Oil Pollution Regulations?
Which is a characteristic of warm air masses?
If you find a victim that is unconscious. What vital signs is an immediate threat to life?
When an Official logbook is not required, an unofficial logbook is required to be kept aboard for review by a marine inspector for __________.
Which extinguishing agent is most effective on a mattress fire?
If you are required to jump from any height from your vessel when should the external flotation bladder of an immersion suit be inflated?
A man aboard a vessel, is signaling by raising and lowering his outstretched arms to each side. What does this signal indicate?
Which action is routinely performed at the annual servicing and inspection of a dry chemical cartridge- operated portable fire extinguisher?
Which officer is responsible for the sanitary condition of the engineering department?
What is the function of the bypass valve on the self-contained breathing apparatus?
On a class "B" fire, which portable fire extinguisher would be the LEAST desirable?
Beyond the area of state ownership in the U.S. outer continental shelf, the right to drill is controlled by the __________.
Each EPIRB shall be tested using the integrated test circuit and output indicator every __________.
The muster list shows each rig hand's muster station, his duties during abandonment, basic instructions, and __________.
The DEEP DRILLER, loaded as shown in Sample Load Form #1 (Transit), suffers minor damage which results in flooding in tank 1S. You may pump from __________.
Which is NOT a required entry in the ship's Official Logbook?
The helicopter deck on an offshore drilling unit is required to be fitted with perimeter lights in alternating colors of __________.
Accumulations of H2S gas on a MODU can be dangerous. It is imperative that personnel know that H2S gas possesses which of the listed characteristics?
In an emergency, if you must jump from a MODU, what is the best procedure to follow?
The COASTAL DRILLER is loaded as shown in the Sample Load Form #1 (Rig Move). What is the margin on the maximum allowable KG if winds increase to greater than 70 knots, and the TOC is changed to the recommended value?
What danger is presented if a waterspout passes over a MODU?
Periodic surveys to renew the load line assignment for a MODU must be made at intervals not exceeding __________.
In the piping systems of a MODU, what type of valve gives the least resistance to fluid flow when fully open?
Port ballast pump #1 on the DEEP DRILLER has failed. If you want to deballast the forward-port column using port ballast pump #2, it is necessary to open valves __________.
The DEEP DRILLER's lightweight is the condition prior to loading __________.
If H2S exposure is anticipated, fixed monitoring devices aboard a MODU should have a low level concentration alarm to alert personnel. at what concentration level will the alarm activate?
Each emergency light must be marked with __________.
The required portable radio apparatus on an international voyage must be stowed in __________.
Which of the following would be the most probable location to encounter explosive and flammable gasses on a MODU?
While in transit, the DEEP DRILLER suffers flooding in the starboard pump room. Both starboard bilge pumps are inadequate to dewater the pump room. You may supplement the performance of the bilge pumps by using the __________.
Aboard the DEEP DRILLER, the bilge pumps take suction from the pump rooms, cofferdam, void area, access trunk, and which other area?
When should the emergency position-indicating radio beacon be activated after abandoning a MODU?
The DEEP DRILLER is loaded as shown in the Sample Load Form #1 (Transit). Weather conditions require ballasting to survival draft. Assume that 4087 long tons of ballast are added at an average VCG of 8.32 feet. What would be the value of uncorrected KG?
The lightweight vertical moments for the DEEP DRILLER are __________.
Requirements for H2S preparation and equipment usage aboard MODU's in U.S. offshore waters are administered by which of the following organizations?
How must each storage tank for helicopter fuel on a MODU be marked?
On a semisubmersible drilling unit, increasing riser tension increases __________.
When a semisubmersible rig under tow veers from side to side on its tow line, the best way of controlling the action is to __________.
The DEEP DRILLER is under tow at a 20-foot draft. The rig motions are close to exceeding the limits for critical pitch and roll. The rig is also experiencing occasional pounding on the horizontal braces. In this situation you should __________.
The DEEP DRILLER is loaded as shown in the Sample Load Form #5 (Survival) when an unexpected slowly increasing port list and bow down trim occurs. A leak in C1P is found. By deballasting from ballast tanks 2P and 3P, the inclination slowly decreases. The increase in the transverse free surface correction is __________.
What is the weight of barite in P-tank #4 of the DEEP DRILLER if the ullage is 3.4 feet?
The DEEP DRILLER is loaded as shown in Sample Load Form #5 (Survival). While the unit is deballasting, starboard valve 5 fails in the closed position. You may deballast from tank 2S by pumping from tank 1S after opening valves 6 and __________.
The DEEP DRILLER, at 60.0 feet draft in sea water, has VM = 974,441 foot-long tons, LM = 40,301 foot-long tons, TM = 3 foot-long tons, FSML = 30,572 foot-long tons, and FSMT = 18,732 foot-long tons. What is the KG corrected for longitudinal free surface effects?
The end of the joint with the exterior threads is called the __________.
The DEEP DRILLER is drilling at 60 feet draft at a corrected KG of 54.0 feet. Ballast added or discharged to remain at a constant draft is at a VCG of 10 feet. How much non-liquid load would have to be removed from an average height of 130 feet above the keel to meet the maximum allowable KG at a draft of 60 feet for winds greater than 70 knots?
The motion that can significantly increase mooring line tension is __________.
The DEEP DRILLER is planning to operate while loaded as shown in the Sample Load Form #3 ( Preparing to Drill). What is the margin between KGT and maximum allowable KG?
Laying down drill pipe from the derrick of a semisubmersible on location reduces the __________.
Hydrogen sulfide in explosive concentrations has been detected on the drill floor and the abandon rig signal has been sounded. Which of the following would be the safest way to evacuate?
Survival practice in the mooring system is to slack off the tensions on the leeward side and __________.
While in ocean transit, the COASTAL DRILLER has a roll period of four seconds. What would be the largest angle each side of vertical that does not exceed the design limit of the legs?
The COASTAL DRILLER is loaded as shown in the Sample Load Form #1 (Rig Move). What is the margin on the maximum allowable KG if winds remain less than 70 knots?
The COASTAL DRILLER has a trim of 2.13 feet by the stern. The draft in sea water at the forward draft marks is observed to be 8.0 feet. The KMT is __________.
The COASTAL DRILLER has sufficient reserve stability to overcome damage due to flooding of any one watertight compartment in winds up to __________.
The maximum draft to which a drilling unit may be safely loaded is called __________.
The number of certificated able seamen and lifeboatmen required on a MODU is determined by the __________.
The COASTAL DRILLER, in transit with winds expected to exceed 70 knots, must lower the legs to 60.5 feet below the hull in order to meet the requirements for leg strength and __________.
The COASTAL DRILLER, while in transit, expects the winds to increase to 75 knots. In order to meet the stability and leg strength requirements, the tip-of-can (TOC) position should be at __________.
On the COASTAL DRILLER, the level of water in each of two pump bilge pits is monitored by __________.
On offshore drilling units fitted with fixed CO2 systems, the system must withstand a bursting pressure of at least __________.
The rotary of the COASTAL DRILLER is located 36 feet aft of the transom and 6 feet to starboard of the centerline. The hook load is 300 kips. Considering the changes to lightweight shown in the Operating Manual, the maximum amount of setback is __________.
To what distance below the hull must the legs of the COASTAL DRILLER be lowered in order to meet the stability and leg strength requirements during the wind speeds greater than 70 knots?
You are aboard a vessel which is near a platform engaged in oil exploration. Under U.S. pollution regulations, you may NOT discharge garbage if you are within __________.
Air gap is the vertical distance between the bottom of the hull and the __________.
If help has not arrived in 10-12 hours after you abandon a remotely-located MODU in a survival craft, which of the following would be the best course of action?
What maximum wind velocity is assumed when determining the limits of elevated service for the COASTAL DRILLER?
You are operating a liftboat. Before starting jacking operations, you should __________.
When a wind force causes a floating MODU to heel to a static angle, the __________.
Dry chemical fire extinguishers are effective on which type(s) of fire?
Recharging a previously used cartridge operated dry chemical extinguisher is accomplished by __________.
Where would you find the FCC authorization for transmitting on your rig's EPIRB?
At the required fire drill, all persons must report to their stations and demonstrate their ability to perform the duties assigned to them __________.
A jack-up drilling rig being towed must __________.
A life preserver or buoyant work vest is required to be worn on a MODU when a person is __________.
The DEEP DRILLER, at 60.0 feet draft in sea water, discharges 275.8 long tons. What is the new draft?
What type of test determines the pressure at which the formation immediately below the last set casing will take fluid?
Keeping the draft of a MODU at or below the load line mark will ensure that the unit has adequate __________.
Use of air gaps in excess of that stated in the Limits of Elevated Service for the COASTAL DRILLER could result in __________.