IAMI CMFI Exam Study Guide (2026)
Everything the Certified Marine Fire Investigator (CMFI) tests, topic by topic: what each section covers, the facts that come up most, and how to study it. Pair it with the free 15-question practice test.
The exam at a glance
| Questions | No more than 150 true/false and multiple-choice questions |
|---|---|
| Time | No longer than 3 hours |
| Passing score | 80%; results are reported only as pass or fail, and individual scores are not released |
| Format | Closed book, proctored paper exam, graded by the CMI Committee within 30 days. The real exam mixes true/false and multiple-choice items; practice here uses 4-option single-best-answer questions. The CMFI does not certify you as a fire investigator: you must already hold a recognized fire investigator certification |
| Certifying body | International Association of Marine Investigators (IAMI), CMI Committee (CMFI program) |
| Test provider | Proctored at IAMI Annual Training Seminars and other locations set by the IAMI Board; photo ID required |
Mind map: the whole exam on one screen
Read the complete IAMI CMFI study notes for “Fire Science and Fire Dynamics”
Our first full set of comprehensive notes, about 15 minutes of reading: Combustion basics · Flammable limits and vapor density · Heat transfer · Compartment fire development, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.
1. Fire Science and Fire Dynamics
Combustion chemistry, heat transfer, flammable limits and compartment fire development as set out in NFPA 921 and the fire science knowledge areas of NFPA 1033. IAMI publishes no topic weights; this is the base for every origin and cause question.
Key facts
- Flaming combustion needs fuel, an oxidizer, heat and an uninhibited chemical chain reaction (the fire tetrahedron).
- Heat moves by conduction, convection and radiation; radiation dominates fire spread across a compartment near flashover.
- A vapor burns only between its lower and upper flammable limits: gasoline about 1.4% to 7.6%, propane about 2.1% to 9.5%, hydrogen about 4% to 75% by volume.
- Gasoline and propane vapors are heavier than air and collect in bilges; hydrogen from charging batteries is lighter than air and collects high.
- Gasoline's flash point is about minus 45 °F, so it gives off ignitable vapor at any normal temperature; No. 2 diesel's minimum flash point is 125 °F.
- Flashover is the transition to full-room involvement, typically with an upper layer near 600 °C (about 1,100 °F) and about 20 kW/m² radiant heat at floor level.
- After flashover, ventilation controls burning and can create burn patterns far from the origin.
Flashcards
Exam tip: When a question gives a vapor concentration, compare it with the flammable range before anything else: too lean and too rich both fail to ignite.
2. NFPA 921 Methodology, Origin and Cause
The systematic approach of NFPA 921: the scientific method, origin determination, cause classification and expressing conclusions. IAMI's CMFI study guide is based on the current NFPA 921 (2024 edition) and IAMI requires its Vessel Fire Origin and Cause class.
Key facts
- Scientific method steps: recognize the need, define the problem, collect data, analyze data, develop hypotheses, test hypotheses, select the final hypothesis.
- Hypotheses are developed by inductive reasoning and tested by deductive reasoning against all the data.
- Origin is determined from witness information, fire patterns, arc mapping and fire dynamics analysis.
- Cause requires a competent ignition source, the first fuel ignited, an oxidizer and the circumstances that brought them together.
- Cause classifications are accidental, natural, incendiary and undetermined.
- Negative corpus (calling a fire incendiary only because accidental causes were eliminated) is not consistent with the scientific method.
- Opinions are expressed as probable (more likely true than not) or possible; possible is not enough for a cause determination.
Flashcards
Exam tip: If an answer jumps straight from evidence to a final cause without testing, it is wrong. NFPA 921 always wants the hypothesis tested first.
3. Vessel Construction, Materials and Fire Behavior
How hull and superstructure materials, interior finishes and vessel layout affect fire spread and the evidence left behind. IAMI notes the investigator must understand construction methods and materials of vessels.
Key facts
- Fiberglass-reinforced plastic hulls use polyester, vinylester or epoxy resin, which burns and adds a large fuel load; glass fibres remain.
- Balsa and foam cores, upholstery foam and headliners add fuel and can produce rapid fire growth and toxic smoke.
- Aluminum alloys melt around 1,100 to 1,220 °F, so melted aluminum shows temperature, not accelerant use or origin.
- Steel hulls conduct heat to adjacent compartments, so fire can spread through bulkheads without an opening.
- Small enclosed cabins reach flashover quickly; open boats burn as exterior fires driven by wind.
- Boats that burn and sink lose evidence above the waterline and can preserve evidence below it.
- Extent of damage reflects fuel load, ventilation and time, not cause.
Flashcards
Exam tip: Never let the amount of damage decide the cause. Questions that tie severity to accelerants are usually testing this trap.
Test yourself on these topics
Take the free 15-question IAMI CMFI test, then save your results to unlock your Readiness Score and the mistakes bank.
4. Marine Fuel, Electrical and Ignition Sources
Gasoline, diesel and LPG systems, DC and AC electrical systems, batteries, exhaust and engine-related ignition sources, under ABYC standards and 33 CFR Part 183. IAMI's study guide draws on ABYC standards and TIRs and on the CFR.
Key facts
- 33 CFR 183 Subpart J and ABYC H-24 cover gasoline fuel systems; leaking fittings and fill or vent problems are common fuel release points.
- Gasoline boats with enclosed engine spaces need powered ventilation, with a label telling operators to run the blower for 4 minutes before starting (33 CFR 183.610).
Flashcards
Exam tip: For every candidate ignition source ask two things: was it competent to ignite the first fuel, and is there physical evidence it did? Proximity alone proves nothing.
5. Fire Protection Systems, Marinas and Boatyards
Portable and fixed extinguishing systems on boats, and fire protection in marinas and boatyards under NFPA 302 and NFPA 303, the marine fire documents IAMI's study guide refers to.
Key facts
- NFPA 302 covers fire protection for pleasure and commercial motor craft; NFPA 303 covers marinas and boatyards.
- Recreational boats carry Coast Guard approved portable extinguishers under 46 CFR Part 25; B-rated units are for flammable liquid fires.
Flashcards
Exam tip: In multi-boat marina fires, trace spread with wind direction, slip layout and timeline before naming the first boat to burn.
6. Scene Examination, Documentation, Evidence and Safety
Working a vessel fire scene: safety, documentation, examination, evidence collection and spoliation. IAMI requires its Documentation and Fire Scene Examination classes for CMFI candidates.
Key facts
- Assess hazards first: stability and flooding, toxic atmosphere (carbon monoxide, hydrogen cyanide, low oxygen), live batteries and shore power, and fuel.
- Document the vessel and its surroundings before changing anything: photographs, diagrams, measurements and notes.
Flashcards
Exam tip: Safety and documentation come before everything. If an option moves or alters the scene before it is recorded, it is not the first step.
7. Insurance, Legal Considerations and Testimony
Insurance claims, subrogation, spoliation law, reports and expert testimony for vessel fires. IAMI requires its Insurance and Legal Considerations class for CMFI candidates.
Key facts
- Insurers investigate to confirm coverage and cause; an incendiary finding by the insured may bar recovery under intentional act or fraud provisions.
- After paying, the insurer may pursue a subrogation claim against a manufacturer, repairer or marina whose product or work caused the fire.
Flashcards
Exam tip: Legal questions reward method over credentials. The best answer is almost always the one showing documented, tested reasoning.
How to pass
- IAMI does not publish topic weights. Its required core fire classes are vessel fire origin and cause, documentation, fire scene examination, and insurance and legal considerations, so give those the most time.
- Expect NFPA 921 methodology to run through everything: the scientific method, hypothesis testing, cause classification and why negative corpus is rejected.
- Marine questions turn on systems the land-based fire certifications skip: gasoline vapor in bilges, wet exhaust cooling, shore power inlets, ignition protection and fixed engine-room extinguishing systems.
- Approved applications are valid for one year and the exam is given at IAMI seminars, so plan your sitting around the next Annual Training Seminar and confirm with IAMI HQ.
Frequently asked questions
How long should I study for the IAMI CMFI exam?
Most working candidates need 4 to 8 weeks at 45 to 60 minutes a day. Book your exam once your Readiness Score has stayed at 80 or higher for about a week.
Can I take the IAMI CMFI exam online?
Yes. ABYC certification exams are taken with a proctor: online through a remote proctoring service, or for some certifications at the end of an ABYC class. Format: closed book, proctored paper exam, graded by the cmi committee within 30 days. the real exam mixes true/false and multiple-choice items; practice here uses 4-option single-best-answer questions. the cmfi does not certify you as a fire investigator: you must already hold a recognized fire investigator certification. Ask the ABYC Education Department which reference materials are allowed.
What score do I need to pass the IAMI CMFI exam?
80%; results are reported only as pass or fail, and individual scores are not released. The exam has no more than 150 true/false and multiple-choice questions and a time limit of no longer than 3 hours.
What are the most tested topics?
The outline covers fire science and fire dynamics, nfpa 921 methodology, origin and cause, vessel construction, materials and fire behavior, marine fuel, electrical and ignition sources, fire protection systems, marinas and boatyards, scene examination, documentation, evidence and safety, insurance, legal considerations and testimony. Use the free practice test to see which ones you need most.
The premium IAMI CMFI study path
Premium IAMI CMFI prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.
Your step-by-step study path
- 1Fire Science and Fire Dynamics9 key notes, 115 flashcards, then 450 practice questions in 18 sets of 25Notes free with an account
- 2NFPA 921 Methodology, Origin and Cause9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 3Vessel Construction, Materials and Fire Behavior9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 4Marine Fuel, Electrical and Ignition Sources9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 5Fire Protection Systems, Marinas and Boatyards8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 6Scene Examination, Documentation, Evidence and Safety8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25Premium
- 7Insurance, Legal Considerations and Testimony8 key notes, 110 flashcards, then 425 practice questions in 17 sets of 25Premium
- Final step: 6 full mock exams150 questions each, timed like test day. Pass them, then book your exam.Premium
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- One ABYC exam of your choice: any of the 10 certifications, from Marine Electrical to USCG Regulations
- 3,000 practice questions + 6 full mock exams per exam
- 800 flashcards + 60 key notes per exam, by topic, plus mind maps
- Spaced repetition + mistakes bank
- Readiness Score & detailed reports
- Video lessons as they release
- Content updates during your access
- 5 bonuses: numbers and formulas sheet, standards map, study planner and more
- Pass Guarantee: complete the prep, pass or 100% back
Renews once a year until you cancel. We email you before each renewal. Cancel any time from your account; you keep access until the end of the year you've paid for.
Summarized from ABYC's official candidate information and the rules cited, checked November 2026. Confirm current requirements with International Association of Marine Investigators (IAMI), CMI Committee (CMFI program).