46 CFR § 161.013-7 - Signal requirements.

---
identifier: "/us/cfr/t46/s161.013-7"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 161.013-7 - Signal requirements."
title_number: 46
title_name: "Shipping"
section_number: "161.013-7"
section_name: "Signal requirements."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "Q"
subchapter_name: "EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL"
part_number: "161"
part_name: "ELECTRICAL EQUIPMENT"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "46 U.S.C. 3306, 3703, 4302; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; DHS Delegation 00170.1, Revision No. 01.4."
cfr_part: "161"
---


# 161.013-7 Signal requirements.

(a) An electric light must have a flash characteristic of the International Morse Code for S-O-S and, under design conditions,

(1) Each short flash must have a duration of 
1/3 second;

(2) Each long flash must have a duration of 1 second;

(3) The dark period between each short flash must have a duration of 
1/3 second;

(4) The dark period between each long flash must have a duration of 
1/3 second;

(5) The dark period between each letter must have a duration of 2 seconds;

(6) The dark period between each

S-O-S signal must have a duration of 3 seconds.

(b) The flash characteristics described in paragraph (a) must be produced automatically when the signal is activated.