EPIRBs and Distress Signaling Equipment
TL;DR — Uninspected passenger vessels under 100 GT are not required to carry an EPIRB, but any vessel operating on the high seas or beyond three miles from the Great Lakes coastline that is required to carry one must have a Category 1, 406 MHz, float-free, automatically activated unit. Visual distress signals for recreational and small commercial vessels must be Coast Guard–approved pyrotechnics, an electric distress light, or an orange flag in the quantities specified by regulation.
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What the Rule Says
EPIRB Categories and Technology
An EPIRB is an Emergency Position Indicating Radiobeacon that is Type Accepted by the Federal Communications Commission under 47 CFR parts 2 and 80. 46 CFR §25.26-1 The regulations consistently require the Category 1, 406 MHz standard wherever an EPIRB is mandated. A Category 1 unit is float-free and automatically activated; a Category 2 unit is manually activated. The distinction matters because most offshore requirements demand Category 1. 46 CFR §25.26-5
Uninspected Passenger Vessels (UPVs)
This is the rule most directly tested on the OUPV and Master 100 GT exams:
- UPVs less than 100 gross tons — not required to carry an EPIRB. 46 CFR §25.26-10
- UPVs of at least 100 gross tons — must not operate beyond three miles from shore (measured from the territorial sea baseline seaward) or more than three miles from the Great Lakes coastline unless the vessel has onboard a float-free, automatically activated Category 1, 406 MHz EPIRB stowed so it will float free if the vessel sinks. 46 CFR §25.26-10
The practical takeaway: the typical six-pack operator running a 30-foot charter boat is not legally required to carry an EPIRB under this subpart. That does not mean carrying one is inadvisable — it means the exam will test whether you know the threshold is 100 GT, not some other number.
Commercial Fishing Industry Vessels
The rules for fishing vessels, fish processing vessels, and fish tender vessels are more nuanced and depend on vessel length and construction. 46 CFR §25.26-5
Vessels 11 meters (36 feet) or more in length (with galley and berthing, or without galley and berthing) operating on the high seas or beyond three miles from the Great Lakes coastline must carry a float-free, automatically activated Category 1, 406 MHz EPIRB stowed so it will float free if the vessel sinks. 46 CFR §25.26-5
Exception — vessels less than 11 meters, or vessels 11 meters or more with a builder's certification of sufficient inherent buoyancy: These vessels operating on the high seas or beyond three miles from the Great Lakes coastline must have installed, in a readily accessible location at or near the principal steering station, either:
1. A manually activated Category 2, 406 MHz EPIRB; or 2. A float-free, automatically activated Category 1, 406 MHz EPIRB. 46 CFR §25.26-5
Note the key difference: the inherently buoyant vessel may use a Category 2 (manual) unit, whereas the standard fishing vessel 36 feet or more must have Category 1 (automatic float-free).
Vessels Subject to 46 CFR Part 180 (Certain Small Passenger Vessels)
Any vessel subject to 46 CFR Part 180 that operates on the high seas or beyond three miles from the Great Lakes coastline must have onboard a FCC Type Accepted Category 1, 406 MHz EPIRB installed to automatically float free and activate. 46 CFR §180.64
Vessels Subject to 46 CFR Part 199
Vessels subject to 46 CFR Part 199 must carry a Category 1, 406 MHz satellite EPIRB meeting the requirements of 47 CFR Part 80. When underway, the EPIRB must be stowed in its float-free bracket with controls set for automatic activation, mounted so it will float free if the vessel sinks. 46 CFR §199.510
Commercial Fishing Vessels — Cross-Reference to Part 28
Each commercial fishing industry vessel must be equipped with an EPIRB as required by 46 CFR Part 25, Subpart 25.26. 46 CFR §28.150
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Visual Distress Signals (VDS)
Visual distress signals are governed separately from EPIRBs. The accepted devices and quantities are specified in 33 CFR §175.130. 33 CFR §175.130
Three categories of accepted VDS:
1. Electric distress light (46 CFR 161.013) — one unit meets the night only requirement. 33 CFR §175.130 2. Orange flag (46 CFR 160.072) — one unit meets the day only requirement. 33 CFR §175.130 3. Pyrotechnics — must meet the standards in Table 175.130 and be carried in the required quantities. 33 CFR §175.130
Pyrotechnic devices and their requirements (from Table 175.130):
| 46 CFR Approval | Device | Day/Night | Quantity Required | |---|---|---|---| | 160.021 | Hand Held Red Flare | Day and Night | 3 | | 160.022 | Floating Orange Smoke | Day Only | 3 | | 160.024 | Parachute Red Flare | Day and Night | 3 | | 160.036 | Hand-Held Rocket-Propelled Parachute Red Flare | Day and Night | 3 | | 160.037 | Hand-Held Orange Smoke | Day Only | 3 | | 160.057 | Floating Orange Smoke | Day Only | 3 | | 160.066 | Red Aerial Pyrotechnic Flare | Day and Night | 3 |
Combination compliance: A combination of devices may satisfy both day and night requirements together. For example, two hand-held red flares (160.021) plus one parachute red flare (160.024 or 160.036) meets both day and night requirements. Three hand-held orange smoke signals (160.037) combined with one electric distress light (161.013) also meets both day and night requirements. 33 CFR §175.130
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Distress Signaling Priorities
When a vessel is in distress, the priority sequence for signaling is: VHF Channel 16 MAYDAY with DSC if equipped (DSC transmits identity and position automatically), EPIRB activation if rapid response is critical, then visual flares and signal mirror as backup. A MAYDAY transmission must be continued until acknowledged. USCG Boatswain Manual Ch. 7 §7.2
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Why It Matters on the Exam
The OUPV and Master 100 GT written exams test EPIRB and VDS requirements heavily because these are life-safety items with specific, testable thresholds. Examiners favor questions that require you to distinguish between:
- Category 1 vs. Category 2 — automatic float-free vs. manual activation. Most offshore requirements mandate Category 1. 46 CFR §25.26-5
- The 100 GT threshold for UPVs — below 100 GT, no EPIRB is required by 46 CFR §25.26-10. This surprises many candidates who assume any offshore charter vessel must carry one. 46 CFR §25.26-10
- The three-mile trigger — EPIRB requirements activate when operating beyond three miles from shore (measured from the territorial sea baseline) or beyond three miles from the Great Lakes coastline. 46 CFR §25.26-10 46 CFR §180.64
- VDS quantities — the number three appears repeatedly in Table 175.130. Candidates who remember "three" without remembering which devices are day-only vs. day-and-night will miss questions. 33 CFR §175.130
- Day-only vs. night-only vs. day-and-night devices — orange smoke signals are day only; red flares and parachute flares are day and night; the electric distress light is night only; the orange flag is day only. 33 CFR §175.130
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Common Pitfalls
Pitfall 1: Assuming all charter vessels must carry an EPIRB. The regulation is explicit: uninspected passenger vessels less than 100 gross tons are not required to carry an EPIRB. 46 CFR §25.26-10 Many candidates confuse "good seamanship" with legal requirement. The exam tests the legal requirement.
Pitfall 2: Confusing Category 1 and Category 2. Category 1 = float-free, automatic activation. Category 2 = manual activation. The standard offshore requirement is Category 1. Category 2 is only permitted for certain smaller or inherently buoyant fishing vessels. 46 CFR §25.26-5 Stowing a Category 2 unit where a Category 1 is required is a violation.
Pitfall 3: Treating orange smoke as a day-and-night signal. Both hand-held orange smoke (160.037) and floating orange smoke (160.022, 160.057) are day only. Three orange smoke signals alone do not satisfy a night requirement. You must add a night-capable device such as an electric distress light. 33 CFR §175.130
Pitfall 4: Forgetting the stowage requirement. It is not enough to have a Category 1 EPIRB onboard. The unit must be stowed in its float-free bracket with controls set for automatic activation, mounted so it will float free if the vessel sinks. 46 CFR §199.510 An EPIRB locked in a cabin drawer does not meet the requirement.
Pitfall 5: Confusing the "high seas" definition. The high seas means waters beyond a line three nautical miles seaward of the Territorial Sea Baseline as defined in 33 CFR 2.20. 46 CFR §25.26-1 This is not the same as "offshore" in the colloquial sense. The three-mile measurement is from the territorial sea baseline, not from the shoreline as visible on a chart.
Pitfall 6: Mixing up the distress signaling priority sequence. VHF Channel 16 MAYDAY (with DSC if equipped) comes first. EPIRB activation follows if rapid response is critical. Visual signals are backup. The MAYDAY must be continued until acknowledged — you do not transmit once and wait. USCG Boatswain Manual Ch. 7 §7.2
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Quick Check
Q1: An uninspected passenger vessel of 65 gross tons operates 10 miles offshore. Is an EPIRB required?
No. Uninspected passenger vessels less than 100 gross tons are not required to carry an EPIRB. 46 CFR §25.26-10
Q2: A fishing vessel 40 feet in length, with galley and berthing, operates on the high seas. What type of EPIRB is required and how must it be stowed?
A float-free, automatically activated Category 1, 406 MHz EPIRB, stowed so that it will float free if the vessel sinks. 46 CFR §25.26-5
Q3: A vessel operator carries three hand-held orange smoke signals and one electric distress light. Does this combination satisfy both day and night VDS requirements?
Yes. Three hand-held orange smoke signals (160.037) combined with one electric distress light (161.013) meet both day and night requirements. 33 CFR §175.130
Q4: How many hand-held red flares (46 CFR 160.021) are required to meet the visual distress signal requirement, and do they satisfy day, night, or both?
Three hand-held red flares are required, and they satisfy both day and night requirements. 33 CFR §175.130
Q5: A fishing vessel less than 11 meters in length has a builder's certification of sufficient inherent buoyancy. It operates on the high seas. What EPIRB options are available to the owner?
The owner may install either a manually activated Category 2, 406 MHz EPIRB or a float-free, automatically activated Category 1, 406 MHz EPIRB, in a readily accessible location at or near the principal steering station. 46 CFR §25.26-5
Q6: In a distress situation, what is the correct priority order for signaling, and when do you stop transmitting MAYDAY?
First, transmit MAYDAY on VHF Channel 16 (with DSC if equipped, which automatically transmits identity and position). Second, activate the EPIRB if rapid response is critical. Third, use visual flares and signal mirror as backup. Continue transmitting MAYDAY until it is acknowledged — do not stop. USCG Boatswain Manual Ch. 7 §7.2
Q7: An orange flag is carried as the sole visual distress signal. What requirement does it satisfy, and how many are needed?
One orange flag (meeting 46 CFR 160.072 standards) satisfies the day only requirement. It does not satisfy any night requirement. 33 CFR §175.130
Q8: A vessel subject to 46 CFR Part 199 is underway. Where must the EPIRB be stowed and how must the controls be set?
The EPIRB must be stowed in its float-free bracket with the controls set for automatic activation, mounted so it will float free if the vessel sinks. 46 CFR §199.510