Shallow Water Effect - Shiphandling Facts and Rules

Question 1

Full Shallow Water Effect

Answer 1

at 1.2 x draft

Question 2

Significant Shallow Water Effect

Answer 2

at 1.5 x draft

Question 3

Shallow Water Effect Felt

Answer 3

at less than 2 x draft

Question 4

Shallow Water Turning Circle

Answer 4

up to twice that in deep water

Question 5

Shallow Water - Rate of Turn

Answer 5

same as for deep water turn

Question 6

Shallow Water Steering Characteristics

Answer 6

Improved (provided not trimmed by the head)

Question 7

Shallow Water Backing

Answer 7

• Twists more when backed
• may become unreliable (Rowe pg. 26)

Question 8

Engines stopped in Shallow Water

Answer 8

Ship carries her way longer (MacElrevey pg. 18)

Question 9

Shallow Water Waves

Answer 9

Increased wave making

Question 10

Shallow Water speed through the water

Answer 10

Reduced speed for given RPM

Question 11

Shallow Water - trim

Answer 11

Change of trim (bow or stern depending on the ship and initial trim)

Question 12

Shallow Water - Sinkage is…

Answer 12

change in overall draft

Question 13

Shallow Water - Squat is…

Answer 13

change of trim and sinkage

Question 14

Shallow Water - Hydrodynamic Interaction

Answer 14

increases ship to ship and ship to bank effects

Question 15

Shallow Water - Cb > 0.75 squat

Answer 15

tend to squat by the head

Question 16

Squat as two ships pass in Shallow Water channel
(MacElrevey)

Answer 16

• generally increases by 50%
• could be up to 100% depending on ship’s speed and separation

Question 17

Speed with 5 feet UKC
(MacElrevey)

Answer 17

max speed 6 knots

Question 18

Significant factor reducing UKC during a Shallow Water turn

Answer 18

List caused by turn and squat under the hull at the outside of the turn

Question 19

Acceleration ____?____ squat

Answer 19

increases

Question 20

Shallow water - Cb < 0.7 squat

Answer 20

tend to squat by the stern