Monty's Ark Study Center

NAV-70 Study Kit

International & Inland Navigation Rules

Take Practice Test

Exam target

63 correct out of 70 = 90%

Use the quick reference first, then review the rule comparison and take randomized practice tests.

Quick reference · Front

Lights & Day Shapes

Sunset to sunrise and in restricted visibility

Light arcs

Masthead: White · 225°
Sidelights: Red port / green starboard · 112.5°
Sternlight: White · 135°
Towing light: Yellow · 135°
All-round: 360°

Vessel status

NUC: Red over red · two balls
RAM: Red-white-red · ball-diamond-ball
CBD (International): Three red · cylinder
Pilot: White over red
Aground: Anchor lights + red-red · three balls

Fishing & sailing

Trawling: Green over white
Fishing, not trawling: Red over white
Gear >150 m: White light / cone toward gear
Sailing: Sidelights + sternlight
Sail + engine: Power-driven · cone apex down

Towing essentials

Towing astern: Yellow towing light above white sternlight
Tow >200 m: Three masthead whites · diamond
Composite unit: Treated as one power-driven vessel
Memory: Yellow over white: “My hawser's tight”

High-value yellow-light distinction

Towing astern—Both: steady yellow towing light above the white sternlight. Pushing ahead/towing alongside—Inland: tug shows two steady yellow towing lights vertically aft; the vessel pushed ahead shows the special flashing yellow light forward. International: no yellow in that pushing configuration; the tug shows a white sternlight.

Quick reference · Back

Sound Signals

Short ≈ 1 second · prolonged = 4–6 seconds

International maneuvering

1 short: Altering to starboard
2 short: Altering to port
3 short: Operating astern propulsion
5+ short: Doubt or danger

Inland meeting/crossing

1 short: Propose port-to-port
2 short: Propose starboard-to-starboard
Agreement: Other vessel answers the same signal
5+ short: Doubt or danger

Inland overtaking

1 whistle: Pass on overtaken vessel's starboard side
2 whistle: Pass on overtaken vessel's port side
Radio: “Meet on the one/two” describes passing side
Rule 34(h): Agreed VHF arrangement may replace whistle exchange

Restricted visibility

Power, making way: 1 prolonged / ≤2 min
Power, stopped: 2 prolonged / ≤2 min
Sail, fishing, NUC, RAM: 1 prolonged + 2 short / ≤2 min
At anchor: Rapid bell ~5 sec / ≤1 min
Aground: Anchor bell + 3 distinct strokes before and after

Pilothouse shorthand

“One-whistle pass” means leave the other vessel on your port side. “Two-whistle pass” means leave the other vessel on your starboard side. Do not apply that shorthand to International maneuvering signals, where one and two blasts announce course alterations.

Exam traps

Inland vs. International

Rule 14

Head-on

Both alter to starboard. Inland whistle proposals require agreement; International blasts announce the maneuver.

Rule 24

Pushing ahead

Inland uses steady yellow towing lights aft plus the pushed vessel's special flashing yellow forward. International does not.

Rule 28

Constrained by draft

CBD—three red lights and/or cylinder—is an International status without a general Inland counterpart.

Rule 34

One and two blasts

International: course alteration. Inland: passing proposal and agreement.

Rule 34(h)

Bridge-to-bridge radio

Under Inland Rules an agreed radiotelephone arrangement may substitute for the whistle exchange.

Annex V Inland

Special flashing light

Yellow, 50–70 flashes per minute, forward on a vessel being pushed ahead—not the ordinary steady towing light.

Rule-by-rule supplement

Inland & International Comparison

Concise study summaries—not a substitute for the official Rules

Rule	Inland	International
1 · Application	U.S. inland waters and waters specified by statute.	High seas and connected waters navigable by seagoing vessels.
2 · Responsibility	Ordinary practice of seamen; consider special circumstances. Departure only when necessary to avoid immediate danger.
3 · Definitions	Includes special flashing light and Western Rivers terms.	Includes vessel constrained by draft.
4–10 · Conduct	Lookout, safe speed, collision risk, positive action, narrow channels, and traffic separation. Inland-specific channel language applies where stated.
11–18 · In sight	Passing signals are proposals requiring agreement.	Maneuvering signals announce course changes.
19 · Restricted visibility	Not in sight: safe speed, engines ready, radar assessment; avoid port turns for traffic forward of beam except overtaking, and turns toward traffic abeam/abaft.
20–23 · Lights	Display sunset–sunrise and in restricted visibility. Standard arcs and power-driven configurations.
24 · Towing/pushing	Two steady yellow towing lights aft; pushed vessel shows special flashing yellow forward.	White sternlight for pushing/towing alongside; no special flashing yellow.
25–27 · Special vessels	Sailing, fishing, NUC, and RAM lights/shapes substantially parallel; observe stated size exceptions.
28 · CBD	No general counterpart.	May show three all-round red lights and/or cylinder.
29–31 · Pilot/anchor	Pilot white-over-red; anchor and aground lights/shapes; seaplanes/WIG craft comply as closely as possible.
32–33 · Equipment	Defines short/prolonged blasts and whistle, bell, and gong requirements by vessel length.
34 · Maneuvering	One/two blasts propose passing; agreement by same signal. VHF agreement may substitute.	One/two blasts mean altering course starboard/port; special overtaking sequence.
35 · Fog signals	Prescribed signals for making way, stopped, sail/fishing/NUC/RAM/towing, anchor, and aground.
36–37 · Attention/distress	Attention signals must not be mistaken for authorized signals; distress signals are in Annex IV.
38 · Exemptions	Limited grandfather provisions for vessels built before specified compliance dates.