USCG Master 100 cheat sheet

Rule 13 (overtaking): any vessel overtaking any other keeps clear of the vessel being overtaken until finally past and clear; if in doubt whether overtaking, assume overtaking and keep clear.

Rule 14 (head-on): two power-driven vessels meeting head-on or nearly so each alter course to starboard and pass port to port.

Rule 15 (crossing): the vessel with the other on her starboard side is the give-way vessel; she avoids crossing ahead of the stand-on vessel.

Rule 18 hierarchy: power-driven vessels give way to sailing vessels, vessels engaged in fishing, and vessels not under command or restricted in ability to maneuver.

Rule 34 signals: one short = altering to starboard, two short = altering to port, three short = operating astern propulsion; five or more short and rapid = doubt or danger.

Overtaking signals: two prolonged plus one short = passing on the overtaken vessel's starboard side; two prolonged plus two short = port side; two prolonged plus three short = astern.

Light arcs: each sidelight 112.5 degrees, masthead light 225 degrees, sternlight 135 degrees, all-round light 360 degrees.

Rule 19 restricted visibility: proceed at a safe speed for the conditions, sound the required signals, and no vessel has the right of way.

Rule 9 narrow channel: keep as near the outer limit of the channel on your starboard side as is safe and practicable; do not anchor in the channel.

Distance = Speed x Time; in minutes, Time = (60 x Distance) / Speed and Speed = (60 x Distance) / Time.

Compass conversion order TVMDC: True, apply Variation to get Magnetic, apply Deviation to get Compass; add easterly errors, subtract westerly errors.

One minute of latitude equals 1 nautical mile; one minute of longitude equals 1 nautical mile multiplied by the cosine of the latitude.

IALA Region B (United States): entering from sea, red buoys with even numbers pass to starboard, green can buoys with odd numbers pass to port.

Dip of the horizon in nautical miles is approximately 1.17 times the square root of the height of eye in feet.

Geographic range of a light is approximately 1.17 x sqrt(height of eye in feet) + 1.17 x sqrt(height of light in feet).

Rule of twelfths: over the six hours of a tide the fractions of total rise per hour are 1/12, 2/12, 3/12, 3/12, 2/12, 1/12.

Set is the direction toward which a current flows; drift is its speed in knots; the two are plotted as a vector added to the vessel's course and speed.

Light characteristics: F fixed, Fl flashing (under 50 per minute), Q quick (50 to 79), VQ very quick (80 to 159), Iso isophase, Oc occulting.

Safe working load = breaking strength divided by safety factor; use about 5 to 6 for fiber line, 5 for wire rope, and 4 for chain.

Anchoring scope is the ratio of rode length to depth; use about 5:1 to 7:1, and more in heavy weather to keep the anchor shank horizontal.

Bowline makes a fixed loop that will not slip; clove hitch makes fast to a rail or piling; sheet bend joins lines of unequal size; rolling hitch takes a strain on a line.

A right-hand propeller turns clockwise when viewed from astern going ahead; when backing, the stern walks to port.

Righting moment = displacement x GZ; GM = KM minus KG, and free surface liquid reduces the effective GM.

Class B fires involve flammable liquids and greases; use foam, carbon dioxide, or dry chemical, never a solid water stream.

Load line marks: WNA winter North Atlantic, W winter, S summer, T tropical, F fresh water; the fresh water allowance is 1/48 of the summer draft.

The mechanical advantage of a tackle equals the number of parts of the falls supporting the moving block.

Knot families: a bend joins two lines, a hitch fastens a line to an object, and a knot forms a loop or a stopper in the line.

MAYDAY on VHF channel 16 or 2182 kHz is the distress signal for grave and imminent danger requiring immediate assistance.

PAN-PAN is the urgency signal for a serious situation not yet requiring immediate assistance; SECURITE precedes safety navigation or weather messages.

Fire tetrahedron: fuel, oxygen, heat, and chemical chain reaction; removing any one leg extinguishes the fire.

PASS: Pull the pin, Aim at the base of the fire, Squeeze the handle, Sweep the nozzle side to side.

Man overboard: shout the alarm, throw a float, put the rudder hard over toward the side the person fell, and post a lookout.

EPIRB 406 MHz: float-free (Category I) or manual release (Category II); keep it registered, test monthly, and replace the battery at the manufacturer's interval.

The federal blood alcohol limit for operating a commercial vessel is 0.04 percent; refusal to submit to testing can be treated as a violation.

Abandon ship: broadcast MAYDAY with position, don immersion suits, launch the liferaft, take the EPIRB and water, take a head count, and the master departs last.

Cold water below about 70 degrees F causes rapid heat loss from the head and groin; the H.E.L.P. posture conserves heat for a single person in the water.