100+ Free DDE 1000/4000 HP Practice Questions
Pass your Designated Duty Engineer of Steam, Motor, and/or Gas Turbine-Propelled Vessels, 1,000/4,000 HP exam on the first try — instant access, no signup required.
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Key Facts: DDE 1000/4000 HP Exam
DDE04
USCG NMC exam code for DDE 1,000/4,000 HP
U.S. Coast Guard National Maritime Center
70%
Minimum passing score required on each module
USCG NMC examination standards
50
Multiple-choice questions per module (Q630-Q634)
USCG NMC sample examinations
Under 500 GRT
Vessel size limit for DDE endorsement on near-coastal/inland waters
46 CFR 11.524
15 ppm
Maximum oil content for overboard bilge water discharge
33 CFR Subchapter O / MARPOL Annex I
200 nm
Minimum distance from shore for open-ocean ballast water exchange
33 CFR Subchapter O ballast water management
720 degrees
Crankshaft rotation for one full four-stroke diesel cycle
Marine diesel engineering fundamentals
DDE 1,000/4,000 HP candidates are mariners qualifying to be the designated duty engineer on vessels under 500 GRT (tugs, towboats, OSVs) on near-coastal and inland routes. The USCG NMC DDE04 exam is multiple-choice, 50 questions per module, and requires 70% to pass each module. The motor-propulsion path covers Q630 Motor Plants (diesel cycles, scavenging, turbocharging, fuel injection, governors, air start, clutches and drives), Q633 Engineering Safety & Environmental Protection (fire classes and agents, SCBA, combustible gas indicators and percent LEL, enclosed-space entry, Oil Record Book, 15 ppm OWS limit, SOPEP, ballast water), and Q634 General Subjects (marine electricity, refrigeration, hydraulics, steering gear, and stability). Steam (Q631) or gas turbine (Q632) modules are added only for those propulsion modes. NMC publishes current sample exams dated 2025; questions are practical engineroom scenarios citing real pressures, temperatures, and procedures.
Sample DDE 1000/4000 HP Practice Questions
Try these sample questions to test your DDE 1000/4000 HP exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1On a towboat main propulsion diesel engine, how does fuel cetane rating affect the ignition delay period?
2Which statement correctly describes a marine diesel engine such as those used for tugboat propulsion and auxiliary power?
3On a four-stroke-cycle diesel engine, how many degrees of crankshaft revolution are required to complete one full operating cycle in each cylinder?
4In a two-stroke-cycle diesel engine where scavenge air enters at the bottom and exhaust leaves through valves in the cylinder head, what scavenging flow pattern is being used?
5In a naturally aspirated four-stroke diesel cylinder, during which piston position are both the intake and exhaust valves open (valve overlap)?
6A main propulsion engine has wet (replaceable) cylinder liners. What is the defining characteristic of a wet cylinder liner?
7A Fairbanks-Morse main propulsion engine on a river push boat uses two pistons per cylinder moving in opposite directions with no cylinder head. This engine is best described as a:
8When checking the cylinder jacket-water cooling expansion tank on a main propulsion diesel engine at operating temperature, where should the level read in the sight glass?
9Before shutting down a main propulsion diesel engine on a tractor tug after a hard transit, what should ideally be done FIRST?
10Prior to starting a diesel generator engine, at what dipstick level must make-up lube oil be added to the crankcase?
About the DDE 1000/4000 HP Exam
The Designated Duty Engineer (DDE) 1,000/4,000 HP credential authorizes a mariner to serve as the sole engineer on uninspected and certain small vessels of less than 500 GRT, such as tugs, towboats, and offshore supply vessels, on near-coastal and inland waters. The USCG NMC exam code is DDE04. One written exam serves both the 1,000 HP and 4,000 HP tiers; they differ only in the engineroom service required under 46 CFR 11.524. Motor-propulsion candidates take three modules: Q630 Motor Plants, Q633 Engineering Safety & Environmental Protection, and Q634 General Subjects. Steam or gas turbine endorsements add Q631 or Q632 respectively.
Questions
150 scored questions
Time Limit
Varies by module; sites typically allow several hours for the battery
Passing Score
70% per module
Exam Fee
USCG application and evaluation fees apply (NMC fee schedule) (U.S. Coast Guard National Maritime Center (NMC))
DDE 1000/4000 HP Exam Content Outline
Motor Plants (Q630)
Diesel cycles, two- and four-stroke operation, scavenging and turbocharging, fuel injection systems, governors, air starting, clutches and propulsion drives
Lubrication & Cooling Systems
Forced-feed lube oil systems, full-flow vs bypass filtration, strainers, jacket water circuits, thermostats, expansion tanks, charge air coolers
Fuel Systems
Cetane rating and ignition delay, viscosity in cSt, unit injector vs common rail, fuel strainers and cleaning solvents, fuel lubricity
Engineering Safety & Firefighting (Q633)
Fire classes and agents (CO2, foam, dry chemical), SCBA, combustible gas indicators and percent LEL, enclosed-space entry, H2S and gas-free testing
Environmental Protection (Q633)
Oil Record Book signing and corrections, 15 ppm oily water separator limit, SOPEP annual review, 200 nm ballast water exchange, sewage MSD rules
General Subjects (Q634)
Marine electricity, DC series/parallel circuits, batteries and specific gravity, motors and controllers, refrigeration, hydraulics, steering gear, stability
How to Pass the DDE 1000/4000 HP Exam
What You Need to Know
- Passing score: 70% per module
- Exam length: 150 questions
- Time limit: Varies by module; sites typically allow several hours for the battery
- Exam fee: USCG application and evaluation fees apply (NMC fee schedule)
Keys to Passing
- Complete 500+ practice questions
- Score 80%+ consistently before scheduling
- Focus on highest-weighted sections
- Use our AI tutor for tough concepts
DDE 1000/4000 HP Study Tips from Top Performers
Frequently Asked Questions
Is the DDE 1,000 HP exam different from the DDE 4,000 HP exam?
No. One written exam (USCG code DDE04) serves both the 1,000 HP and 4,000 HP tiers. They differ only in the amount of engineroom service required under 46 CFR 11.524, not in the test content.
Which modules must a motor-propulsion candidate take?
Motor-path candidates take three modules: Q630 Motor Plants, Q633 Engineering Safety & Environmental Protection, and Q634 General Subjects. Steam endorsements add Q631 and gas turbine endorsements add Q632.
How many questions are on each module and what score is needed to pass?
Each module is 50 multiple-choice questions, and you must score at least 70 percent on each module to pass it. Modules are scored independently.
What vessels can a DDE 1,000/4,000 HP serve on?
The endorsement applies to vessels of less than 500 GRT on near-coastal and inland waters, such as tugs, towboats, and offshore supply vessels, where the DDE serves as the designated duty engineer.
Does the NMC publish sample questions?
Yes. The NMC posts sample examinations for Q630, Q633, and Q634 on dco.uscg.mil as PDFs. The current samples are dated 2025 and use practical engineroom scenarios, many with illustrations.
What does a combustible gas indicator reading of 100% LEL mean for methane?
Methane's lower explosive limit is 5% by volume in air, so a reading of 100% LEL corresponds to a 5% methane concentration. Above 100% LEL the atmosphere is in or near the explosive range.
What oil content limit applies to an oily water separator discharge?
Under 33 CFR Subchapter O and MARPOL, processed bilge water may be discharged overboard only when its oil content is less than 15 ppm, monitored by the oil content meter and 15 ppm bilge alarm.