USCG COXSWAIN UPDATED FINAL EXAM QUESTIONS AND
ANSWERS FIRM A+
✔✔Center of Gravity - ✔✔Point at which the weight of the boat acts vertically
downwards. Generally, the lower the center of gravity, the more stable the vessel.
✔✔bouyancy - ✔✔Upward force of water displaced by the hull. The force of buoyancy
keeps the boat afloat; however, it may be overcome if too much weight is added.
✔✔Equilibrium - ✔✔When a boat is at rest, the center of buoyancy acting
upwards/vertically is below the center of gravity acting downwards. It is at this point that
a boat is considered to be in equilibrium
✔✔Rolling - ✔✔When a boat rolls, the force of the center of gravity will move in the
same
direction as the roll. The downward force of gravity is offset by the upward
force of buoyancy and causes the boat to heel.
✔✔Heeling - ✔✔Heeling is when the underwater volume of the boat changes shape
causing the center of buoyancy to move. The center of buoyancy will move towards the
part of the hull that is more
deeply immersed. When this happens, the center of buoyancy will no longer be aligned
vertically with the center of gravity.
✔✔Determine if Other Boat is Listing - ✔✔1) Observe the roll of your own boat and for
distressed vessel, observe its roll upon approaching and when under tow.
2) Be aware of external forces- wind, waves, water depth
3) Be aware of control loading, amount of weight and placement, on own and the
distressed craft.
4) If necessary, attempt to keep your equipment aboard your vessel when dewatering
the vessel.
5) Attempt to tow the distressed vessel only after any loss of stability has been
corrected.
6) Adjust course, speed, or both as necessary to decrease rolling or listing
7) Avoid sharp turns or turns at high speed when loss of stability is possible.
✔✔Free Surface Effect - ✔✔Compartment is partly filled with liquid, the liquid will flow
from side to side as the vessel rolls/pitches.
Corrective actions include:
1) Minimize the number of partially filled tanks (fuel, water, or cargo);
2) Prevent cargo from rolling back and forth on the deck,
3) If possible, store cargo low and close to the centerline.
, ✔✔Downflooding - ✔✔The entry of water into the hull, resulting in progressive flooding
and loss of stability.
Corrective actions include:
1) Keep all watertight fittings and openings secured when a vessel is underway
2) Pump out the water.
✔✔Topside Icing - ✔✔Icing can increase the displacement of a boat by adding weight
above the center of gravity causing the center of gravity to rise causing vessel to heel
over and greatly reduces stability
Corrective actions include:
1) Change course, speed, or both to reduce freezing spray and rolling,
2) Physically remove the ice.
✔✔Two Types of Stability - ✔✔Longitudinal and transverse
Longitudinal (Fore/Aft)- stability tends to balance the boat, preventing it from pitching
end-
over-end (Pitch Poling).
Transverse (Athwartships)- stability tends to keep the boat from rolling over (Capsizing)
✔✔Righting Movement - ✔✔Force causing a vessel to react against a roll and return to
an even keel.
✔✔Set and Drift - ✔✔Set is direction the ship is being pushed off course. Drift is the
speed the ship is getting pushed off course.
✔✔Effects of Ebb on Bar/Entrance - ✔✔An outgoing or ebb current running across a
bar builds up a more intense sea than the incoming or flood current. The intense sea
results because the rush of water out against the incoming ground swell slows the wave
speed and steepens the wave prematurely.
✔✔Effects of Current - ✔✔When a vessel is moving with the current, speed over ground
is increased, but speed through water and maneuverability are decreased due to less
water flowing past the rudder.
When a vessel is moving against the current, speed over ground is decreased but
maneuverability is increased. However, at slow speeds, a small course change can
have the bow swing as water pushes on one side of the bow.
✔✔Leeway - ✔✔The drift of an object with the wind, on the surface of the sea.
The sideward motion of a ship because of wind and current, the difference between her
heading (course steered) and her track (course made good). Sometimes called drift.
ANSWERS FIRM A+
✔✔Center of Gravity - ✔✔Point at which the weight of the boat acts vertically
downwards. Generally, the lower the center of gravity, the more stable the vessel.
✔✔bouyancy - ✔✔Upward force of water displaced by the hull. The force of buoyancy
keeps the boat afloat; however, it may be overcome if too much weight is added.
✔✔Equilibrium - ✔✔When a boat is at rest, the center of buoyancy acting
upwards/vertically is below the center of gravity acting downwards. It is at this point that
a boat is considered to be in equilibrium
✔✔Rolling - ✔✔When a boat rolls, the force of the center of gravity will move in the
same
direction as the roll. The downward force of gravity is offset by the upward
force of buoyancy and causes the boat to heel.
✔✔Heeling - ✔✔Heeling is when the underwater volume of the boat changes shape
causing the center of buoyancy to move. The center of buoyancy will move towards the
part of the hull that is more
deeply immersed. When this happens, the center of buoyancy will no longer be aligned
vertically with the center of gravity.
✔✔Determine if Other Boat is Listing - ✔✔1) Observe the roll of your own boat and for
distressed vessel, observe its roll upon approaching and when under tow.
2) Be aware of external forces- wind, waves, water depth
3) Be aware of control loading, amount of weight and placement, on own and the
distressed craft.
4) If necessary, attempt to keep your equipment aboard your vessel when dewatering
the vessel.
5) Attempt to tow the distressed vessel only after any loss of stability has been
corrected.
6) Adjust course, speed, or both as necessary to decrease rolling or listing
7) Avoid sharp turns or turns at high speed when loss of stability is possible.
✔✔Free Surface Effect - ✔✔Compartment is partly filled with liquid, the liquid will flow
from side to side as the vessel rolls/pitches.
Corrective actions include:
1) Minimize the number of partially filled tanks (fuel, water, or cargo);
2) Prevent cargo from rolling back and forth on the deck,
3) If possible, store cargo low and close to the centerline.
, ✔✔Downflooding - ✔✔The entry of water into the hull, resulting in progressive flooding
and loss of stability.
Corrective actions include:
1) Keep all watertight fittings and openings secured when a vessel is underway
2) Pump out the water.
✔✔Topside Icing - ✔✔Icing can increase the displacement of a boat by adding weight
above the center of gravity causing the center of gravity to rise causing vessel to heel
over and greatly reduces stability
Corrective actions include:
1) Change course, speed, or both to reduce freezing spray and rolling,
2) Physically remove the ice.
✔✔Two Types of Stability - ✔✔Longitudinal and transverse
Longitudinal (Fore/Aft)- stability tends to balance the boat, preventing it from pitching
end-
over-end (Pitch Poling).
Transverse (Athwartships)- stability tends to keep the boat from rolling over (Capsizing)
✔✔Righting Movement - ✔✔Force causing a vessel to react against a roll and return to
an even keel.
✔✔Set and Drift - ✔✔Set is direction the ship is being pushed off course. Drift is the
speed the ship is getting pushed off course.
✔✔Effects of Ebb on Bar/Entrance - ✔✔An outgoing or ebb current running across a
bar builds up a more intense sea than the incoming or flood current. The intense sea
results because the rush of water out against the incoming ground swell slows the wave
speed and steepens the wave prematurely.
✔✔Effects of Current - ✔✔When a vessel is moving with the current, speed over ground
is increased, but speed through water and maneuverability are decreased due to less
water flowing past the rudder.
When a vessel is moving against the current, speed over ground is decreased but
maneuverability is increased. However, at slow speeds, a small course change can
have the bow swing as water pushes on one side of the bow.
✔✔Leeway - ✔✔The drift of an object with the wind, on the surface of the sea.
The sideward motion of a ship because of wind and current, the difference between her
heading (course steered) and her track (course made good). Sometimes called drift.
