Deck General & Safety Study Guide
The broadest OUPV exam section: fire safety, life-saving equipment, stability, pollution regulations, distress signals, weather, and seamanship — all in one place.
Section Overview — Topic Weights
Approximate question distribution based on USCG exam blueprints. These weights shift slightly across exam variants — treat them as study-priority guides, not guarantees.
Fire Safety — Class Reference
Fire classification determines which extinguishing agent to use. The wrong agent can spread the fire or create a hazard. Know this table cold.
| Class | Fuel Type | Correct Agents |
|---|---|---|
| A | Ordinary combustibles — wood, paper, cloth, rubber | Water, dry chemical, foam |
| B | Flammable liquids and gases — gasoline, oil, grease, propane | CO₂, dry chemical, halon substitutes, foam (NOT water — spreads the fire) |
| C | Energized electrical equipment — wiring, motors, panels | CO₂, dry chemical (NEVER water — shock hazard; NEVER foam) |
| D | Combustible metals — magnesium, titanium, sodium | Special dry powder only — water, CO₂, and standard dry chem make it worse |
| K | Cooking oils and fats (high-temperature kitchen fires) | Wet chemical agent — smothers and saponifies the oil |
Life-Saving Equipment
Know the specific requirements, not just the definitions. The exam tests when each device is required and what it cannot substitute for.
Required on uninspected vessels operating beyond 3nm; turns most unconscious wearers face-up; minimum 22 lbs buoyancy for adults
Best for offshore/rough water; bulky but most protective
Acceptable for near-shore/calm water use; turns some unconscious wearers face-up; minimum 15.5 lbs buoyancy
NOT acceptable as substitute for Type I in offshore requirements
For calm, inland water; conscious wearer must hold head upright; minimum 15.5 lbs buoyancy; most common style
Wearable PFD — satisfies one-per-person requirement for vessels under 16 ft if acceptable for conditions
Ring buoy or cushion; must be immediately accessible; required on vessels 16 ft and over in addition to wearable PFDs
Cannot substitute for wearable PFD; must be thrown to conscious victim
Activates automatically when submerged 1–4 meters; transmits 406 MHz to COSPAS-SARSAT + 121.5 MHz homing; must be registered with NOAA
Category I = float-free automatic. Category II = manual activation only
Manually activated only; registered to a person (not a vessel); 406 MHz + optional GPS; FCC license required; 24-hour minimum battery
Not a vessel EPIRB substitute; satisfies personal-use distress requirement
Navigation Lights & Shapes — Quick Reference
This overlaps with the ColRegs section. If you have already mastered Rules of the Road light arcs, review the display requirements below — the Deck General section focuses on when and which vessel, not the arc geometry.
| Situation | Lights Required |
|---|---|
| Power vessel underway (<50m) | Masthead (fwd) + sidelights + stern white |
| Power vessel underway (≥50m) | 2 masthead (fwd lower, aft higher) + sidelights + stern |
| Sailing vessel underway (engine off) | Sidelights + stern white; OR combined tri-color at masthead |
| Sailing vessel using engine (motorsailing) | Same as power vessel |
| Vessel at anchor (<50m) | All-around white (forward, visible 360°) |
| Vessel at anchor (≥50m) | All-around white fwd + all-around white aft (lower) |
| Vessel aground | Anchor lights + 2 all-around red vertically |
| Towing (tow ≤200m) | 2 masthead vertically + sidelights + stern + yellow towing light |
| Not Under Command (NUC) | 2 all-around red vertically + sidelights + stern if making way |
| Restricted in Ability to Maneuver (RAM) | Red-white-red vertically + sidelights + stern if making way |
Navigation lights must be displayed from sunset to sunrise and during restricted visibility. Day shapes replace lights during daylight hours.
Stability Concepts
The exam typically asks 4–6 stability questions. Focus on cause-and-effect: what action raises G, lowers GM, or triggers free surface effect.
Center of Gravity (G)
The point where all the vessel's weight acts downward. Adding weight raises G; removing weight lowers G.
Center of Buoyancy (B)
The geometric center of the underwater hull volume. Shifts outward as the vessel heels, providing a righting force.
Metacentric Height (GM)
The vertical distance between G and the metacenter (M). Positive GM (M above G) = stable vessel. Negative GM = capsizing.
Free Surface Effect
Liquid sloshing in a partially filled tank raises the effective center of gravity, reducing GM and stability.
Angle of Loll
When GM is zero or negative, the vessel rests at a heel angle rather than upright. Correcting requires lowering G (adding ballast low, removing topside weight).
Stability loading rules — commit these to memory
- Add weight low and on the centerline — lowers G, improves stability
- Remove weight from high positions — lowers G, improves stability
- Keep fuel/water tanks full or empty — eliminates free surface effect
- Never load passengers or heavy gear on the bridge deck or flybridge beyond limits
- A list to one side usually indicates off-center weight, not free surface
Weather — Exam Essentials
Weather questions focus on the Beaufort scale, front types, and reading basic forecasts. Learn the thresholds and characteristic signs.
Beaufort Scale — Key Thresholds
| Force | Wind (kts) | Description |
|---|---|---|
| 0 | < 1 | Calm — mirror sea |
| 3 | 7–10 | Gentle breeze — small wavelets |
| 6 | 22–27 | Strong breeze — large waves, whitecaps |
| 7 | 28–33 | Near gale — sea heaps up |
| 8 | 34–40 | Gale — moderately high waves |
| 10 | 48–55 | Storm — very high waves |
| 12 | ≥ 64 | Hurricane force |
Front Characteristics
Fast-moving; narrow band of severe weather; sudden wind shift (veers clockwise in N hemisphere); rapid clearing behind front; steep pressure gradient. Approach: falling pressure, increasing SW wind, CB clouds.
Slow-moving; wide band of clouds/rain (200–300 miles); gradual temperature rise; lower clouds as front approaches; SE to S winds ahead of front; fog risk behind front.
Cold front overtakes warm front; complex weather mix; associated with mature low-pressure systems. Often brings prolonged precipitation.
In Northern Hemisphere: face the wind, low pressure is to your right. Used to locate storm centers.
Pollution Regulations Quick Reference
Know the discharge thresholds and distance rules. The exam loves the specific numbers — 3nm, 12nm, 25nm, 15 ppm, 5 gallons, 400 gallons.
No oil discharge within 3nm of U.S. baseline. Beyond 3nm, bilge water discharge allowed only if < 15 ppm using oily water separator. Machinery spaces of ships 400 GT+: 12nm limit.
Oil Record Book, MARPOL placard (26 ft+), oily water separator (400 GT+)
U.S. implementation of MARPOL. A discharge of ≥ 5 gallons that causes a sheen must be reported. A ≥ 400-gallon discharge is always reportable to the National Response Center (800-424-8802).
Immediate report for sheen-causing spills; written report within 14 days for significant spills
No discharge of untreated sewage within 12nm. MSD Types: Type I = flow-through treatment, Type II = advanced treatment, Type III = holding tank (pump-out only). No-discharge zones prohibit any overboard discharge.
USCG-approved MSD; Y-valve sealed in no-discharge zones; pump-out facility access
No plastics overboard ever, anywhere. Food waste: may be discharged 3+ nm offshore (comminuted/ground: 3nm; not comminuted: 12nm). No dunnage, lining, or packing material within 25nm.
Garbage management plan (vessels 12m+); garbage record book (vessels 100 GT+ or certified for 15+ persons)
Visual Distress Signals (VDS)
Required on all vessels operating on coastal waters, the Great Lakes, territorial seas, and those rivers/lakes connected to the sea where a vessel can travel more than 2nm from the shore.
3 orange smoke signals OR combination device (day/night)
3 red parachute flares OR 3 red handheld flares OR electric distress light (SOS pattern)
Any combination that satisfies both day and night: e.g., 3 combination red flares
Orange flag (signal flag or USCG-approved) OR approved daytime device
Electric distress light (SOS) OR approved nighttime device
Orange flag + electric light satisfies both on inland waters
VDS Expiration & Validity
- Pyrotechnic signals (flares) expire after 42 months from manufacture date — stamped on the device
- Expired flares may be kept as extra signals but do NOT count toward the required minimum
- Non-pyrotechnic signals (electric distress light, orange flag) do not expire but must be in serviceable condition
- The electric SOS distress light must flash the international SOS pattern (··· — — — ···) at 50–70 flashes per minute
- Vessel under oars (non-motorized) under 16 ft on coastal waters: must have at least one VDS at night
Worked Practice Questions
A fire breaks out in the engine room from a fuel line leak. The correct extinguisher type is:
- A. Type A (water)
- B. Type B (CO₂ or dry chemical)
- C. Type C (CO₂ only)
- D. Type A or B
Flammable liquid fires (gasoline, diesel, oil) are Class B. Use CO₂, dry chemical, or foam. NEVER water — water will spread the burning fuel and can cause a flash explosion. Type C is for electrical fires (energized equipment). Once you cut power to electrical equipment, it becomes a Class A fire.
The trap is answering 'C' because it's an engine room (electrical). But the cause is a fuel leak — the fire class is determined by what is burning, not where it is.
A vessel operating beyond 3 nautical miles offshore is required to carry which type of PFD for each person aboard?
- A. Type II or better
- B. Type III or better
- C. Type I only
- D. Type I or Type II
For uninspected recreational vessels operating beyond 3nm (coastal/offshore), USCG regulations require at minimum a Type II (near-shore) PFD for each person. Type I is recommended and may be required by specific vessel inspections, but the minimum standard is Type II for offshore use. Type III devices are not adequate for offshore/rough water because they do not reliably turn an unconscious wearer face-up.
Many candidates choose 'C' (Type I only) because they associate offshore with the most protective PFD. But the regulatory minimum beyond 3nm is Type II or better — Type I is not the exclusive requirement.
Which of the following best describes free surface effect?
- A. The tendency of a vessel to return to upright after heeling
- B. The loss of stability caused by liquids sloshing in partially filled tanks
- C. The shift of the center of buoyancy as the vessel heels
- D. The upward force of water on the hull
Free surface effect occurs when a tank is partially filled: as the vessel heels, liquid shifts to the low side, effectively raising the center of gravity (G) and reducing metacentric height (GM). This reduces the righting moment and can cause capsizing. The fix is keeping tanks completely full or completely empty when operating in rough conditions. Answer A describes positive GM/righting moment; C describes buoyancy center shift (which is normal and stabilizing); D describes buoyancy force generally.
Answer C is the most common wrong choice — students confuse the shift of B (center of buoyancy, which is stabilizing) with the shift of effective G (which is destabilizing in free surface effect).
Exam Strategy — Deck General & Safety
What to prioritize
- Fire classes + extinguisher agents — always tested, always confusing. Know Class C = no water.
- PFD types and offshore requirements — know Type I vs II vs III differences cold.
- EPIRB vs PLB — float-free vs manual, vessel vs person registration.
- Free surface effect — understand cause (liquid sloshing) and fix (fill or empty tanks).
- MARPOL distance numbers — 3nm, 12nm, 25nm, 15 ppm. The exam loves the specifics.
- VDS pyrotechnic expiration — 42 months; expired ones don't count.
Common mistakes in this section
- Choosing water for a fuel fire — never correct for Class B.
- Confusing Type III PFD as acceptable for offshore use — it is not.
- Thinking a PLB satisfies the EPIRB requirement for a vessel — it does not.
- Misidentifying free surface effect as a list — list = off-center weight, not sloshing tanks.
- Forgetting that expired pyrotechnics don't count toward VDS minimums.
- Missing the 5-gallon reporting threshold for oil spills under APPS.
- Assuming "plastics overboard" is allowed at 25nm — plastics are NEVER allowed overboard.
Frequently Asked Questions
What passing score is required for Deck General & Safety on the OUPV exam?
Deck General & Safety requires a 70% passing score on the OUPV exam — you must answer at least 35 of 50 questions correctly. Unlike Rules of the Road (which requires 90%), the 70% threshold gives you more margin, but the topic breadth is wide: fire safety, life-saving equipment, navigation lights, distress signals, stability, weather, pollution, and general seamanship all appear.
What is the difference between an EPIRB and a PLB?
An EPIRB (Emergency Position Indicating Radio Beacon) is a vessel-mounted device that transmits on 406 MHz to COSPAS-SARSAT satellites and 121.5 MHz for homing. Category I EPIRBs float free and activate automatically when submerged; Category II require manual activation. A PLB (Personal Locator Beacon) is a smaller, personally worn device — registered to a person, not a vessel — and must be manually activated. PLBs are not a substitute for a required EPIRB on vessels but satisfy personal distress requirements. Both transmit GPS coordinates when equipped.
What are the MARPOL discharge rules for oil at sea?
Under MARPOL Annex I (incorporated into U.S. law by the Act to Prevent Pollution from Ships): no oil discharge is permitted within 3 nautical miles of the U.S. baseline. Beyond 3nm, bilge water may be discharged only if oil content is less than 15 ppm, the vessel is underway, and an oily water separator with alarm is in use. For machinery space bilge water from vessels 400 GT or more, the threshold is 15 ppm beyond 12nm. Penalty: civil fines up to $25,000 per day. Required equipment: Oil Record Book, MARPOL placard (vessels 26 ft or more), and in U.S. waters a fixed or portable pump-out for vessels with installed toilets.
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