Manuevering Characteristics and Interaction

Question 1

What factors are associated with interaction?

Answer 1

Speed, depth of water, proximity of obstructions, the hull form and the maneuvering aids operational to the vessel

Question 2

What are ship performance factors?

Answer 2

Corrosion, hull growth, hull damage, engine maintenance.

Question 3

How can interaction be observed?

Answer 3

As squat, a bank cushion affect, or an unexpected movement between two vessels in close proximity.

Question 4

What information should be found in the ship’s “pilot card” or “maneuvering booklet”?

Answer 4

Ship’s general particulars, main maneuvering equipment characteristics, hull particulars, maneuvering characteristics in deep and shallow water, main engine operating characteristics, wind forces and drift effects.

Question 5

What info should be included in the “ship general particulars” section of the Pilot Card?

Answer 5

Vessel name, year of build, distinctive identifications numbers, GT, deadweight, load line displacement, the principle dimensions; LOA, molded breath and depth, load line draft, FWA, air draft.

Question 6

What info should be included in the “Maneuvering Equipment and Equipment Characteristics” section of the Pilot Card?

Answer 6

M/E type and # of units, combined power output; the # and type of propellers and propeller diameter, pitch and direction of rotation; the type and # of rudders and location.

Question 7

What info should be included in the “Shallow Water Maneuvering Characteristics” section of the Pilot Card?

Answer 7

Curves should be drawn showing maximum squat values with different speeds and blockage factors with the ship at various drafts.

Question 8

What info should be included in the “Deep Water Maneuvering Characteristics” section of the Pilot Card?

Answer 8

Graphs from turning circle test showing advance and transfer; times and speeds at 90 deg., 180 deg., 270 deg., 360 deg.; acceleration and speed characteristics, and stopping capabilities and distances from various speeds and conditions.

Question 9

What happens to the pivot point when making a turn?

Answer 9

The resultant turning motion on the vessel sees the pivot point following the arc of the turn.

Question 10

What happens to the pivot point when at anchor?

Answer 10

The pivot point goes to the bow-effectively the hawse pipe.

Question 11

What causes speed loss during hard over round turns? How much speed loss is typical?

Answer 11

The rudder angle imposed causes considerable drag along with hydrodynamic forces. 30-40% loss in speed is typical.

Question 12

How will a list on a vessel affect a hard over round turn?

Answer 12

The completion time of the round turn will be extended. Also, turning towards the list will generate a larger turning circle than turning away from the list.

Question 13

Does the type of rudder influence the turning circle?

Answer 13

Yes, a flap-type rudder compared to a traditional semi-balanced rudder will generate a tighter turning circle.

Question 14

How does the shape and design of the rudder affect the size of the turning circle?

Answer 14

Rudders with a large surface area will reduce the size of the turning circle along with having a small clearance between the rudder and the hull.

Question 15

Does cargo distribution affect handling characteristics?

Answer 15

Yes-cargo placed around the mid-ships section sections of the vessel vs. cargo placed a the extremities of the vessel will improve handling and responsiveness to the helm.

Question 16

What are some effects of rudder angle on turning circles?

Answer 16

Employing a large rudder angle will lead to tighter turning circles but will lead to greater loss of speed.

Question 17

In most cases what area of the vessel describes the perimeter of the turning circle?

Answer 17

The pivot point.

Question 18

What are some negative aspects of propeller cavitation?

Answer 18

Propeller cavitation creates a vortex at the blade tips leading to speed loss. This action can lead to pitting of the propeller will lead to further inefficiencies of the propeller and further loss of speed.

Question 19

What are common types of propellers?

Answer 19

Right-hand fixed pitch, CPP, contra-rotating, multi-blade, twin, triple, and quadruple propeller sets, pod propulsion units, kort nozzle systems, and Azi-pod systems.

Question 20

What are some advantages of controllable pitch propellers?

Answer 20

If a blade is damaged they can be replaced one blade at a time; the constant rotating shaft allows for shaft generator; immediate response to amount and direction of power from the wheelhouse.

Question 21

What is real slip?

Answer 21

Occurs as the result of physical conditions between the propeller and the water in which it is immersed. It should only be positive.

Question 22

What is apparent slip?

Answer 22

Concerned with facts of real slip and additionally the effects of wind or current–can be positive or negative.

Question 23

How do you determine engine speed?

Answer 23

Pitch in feet times RPM times 60 divided by 6076 feet.

Question 24

How do you determine slip?

Answer 24

% slip = Engine speed minus ship’s speed divided by engine speed. Will be positive if engine speed is greater the ship’s speed.

Question 25

What are the tree classes of high speed craft mandated by IMO HSC code in 1994?

Answer 25

Cat A-not more than 450 passengers that can be evacuated safely in time to prevent hypothermia in persons in survival crafts in no more the 4 hours. Cat B-high speed passenger craft other than Cat A capable of maintaining the main functions and safety systems and to navigate safely after the damage of any one compartment. Cargo craft class-defines as any high speed craft other than a passenger craft which is capable of maintaining the main functions of safety systems of unaffected spaces after damage to any one compartment.

Question 26

What is blockage factor?

Answer 26

The proportion of the vessels mid-ship section divided by the cross sectional area of the channel, river, or canal.

Question 27

What happens when two vessels are passing in a narrow channel in regards to squat?

Answer 27

The blockage factor is increased so that the value of squat experienced could be nearly doubled.

Question 28

What are expected ship responses to squat?

Answer 28

The location of LCB will determine the trimming effect and have a direct relation to the squat value; high engine RPM’s will lead to increased stern trim; the length to breath ration can increase or decrease the squat value ie. short stubby ships will have a greater squat value than long narrow beam vessels; a high ration of breadth to channel width will lead to a higher value of squat; vessels with large block coefficient Cb will experience greater effects from squat; greater effects of squat are experienced by vessels trimmed by the bow than the stern.