Asking a drawbridge to open
Navigation Rules, lights & bridges · Power & sail
Under 33 CFR part 117 you ask a drawbridge to open by horn, visual signal or radio, and you repeat the signal until the drawtender acknowledges it. A bridge must open promptly and fully on signal unless its own entry in subpart B says otherwise. Asking for an opening you don't need is prohibited.
- Five short blasts from a boat is a request only for vessels the bridge must pass during a scheduled closure period. From the bridge it means 'not now' (33 CFR 117.15(b)(3), (b)(5)).
- Complaints about a bridge that unreasonably delays an opening go to the Coast Guard District Commander for that bridge (33 CFR 117.9, 117.49).
Requesting an opening
- Sound signal: one prolonged blast (4 to 6 seconds) followed, within 3 seconds, by one short blast (about 1 second), on a horn, whistle, hailer or similar device loud enough for the drawtender to hear (33 CFR 117.15(b)).
- Visual signal: a white flag, or a white, amber or green light, raised and lowered vertically (33 CFR 117.15(c)(1)).
- Radio: a radiotelephone may carry the same messages. You and the drawtender keep monitoring that frequency until you have cleared the draw; if radio contact can't be made or kept, use sound or visual signals (33 CFR 117.15(d)).
- Repeat your signal until the drawtender acknowledges it in some way before you proceed (33 CFR 117.15(a)(1)).
- Part 117 does not set one national channel. A bridge may carry a sign showing its VHF calling and working channels (33 CFR 117.24), and some bridge entries in subpart B name a channel. Check the sign, the subpart B entry or the Coast Pilot.
The bridge's replies
- Opening now: the same prolonged-plus-short blast; a white flag or white, amber or green light raised and lowered; or a fixed or flashing white, amber or green light, given within 30 seconds of your signal (33 CFR 117.15(b)(4), (c)(2)).
- Can't open now, or open and about to close: five short blasts; a red flag or light swung horizontally; or a fixed or flashing red light, within 30 seconds. The bridge repeats it until you acknowledge (33 CFR 117.15(b)(5), (c)(3)-(4)).
- If the draw is already open as you approach, still give the opening signal. With no acknowledgment within 30 seconds, you may go through with caution (33 CFR 117.21).
Several bridges or several boats
- For bridges close together, signal the first; once it acknowledges that it will open promptly, signal the next, and so on (33 CFR 117.17).
- When several boats arrive together, each signals separately and the drawtender answers each in turn. A drawtender need not answer boats gathered for a scheduled opening (33 CFR 117.19).
Requests you must not make
- Don't signal for an opening if your boat would fit under the closed span once every lowerable, non-structural fitting not essential to navigation is lowered (33 CFR 117.11(a)). See the air draft topic.
- Don't signal a drawbridge to open for any purpose other than passing through it (33 CFR 117.11(b)).
The rules: 33 CFR 117.5 · 33 CFR 117.9 · 33 CFR 117.11 · 33 CFR 117.15 · 33 CFR 117.17 · 33 CFR 117.19 · 33 CFR 117.21 · 33 CFR 117.24 · 33 CFR 117.49
Sources (5)
ecfr.gov · baycitymi.gov · discoverboating.com · nauticalcharts.noaa.gov · navcen.uscg.gov
A plain-language summary of federal rules for recreational boats, checked against the rules’ own text and a second source, and written in our own words. It isn’t legal advice. States add rules of their own, and rules change — the links above go to the current official text.