Pivot Point - Shiphandling and Facts and Rules

Question 1

Pivot Point - accelerated turn ahead from stopped
(Hooyer vs. Rowe)

Answer 1

• 1 / (L/B) ratio of L from bow (Hooyer)
• moves forward to 1/8L from bow (Rowe)

Question 2

Pivot Point - initial stage of turn with headway

Answer 2

1/4L from bow

Question 3

Pivot Point - steady turn
(Hooyer vs. Rowe)

Answer 3

• 1/3L from bow (Hooyer)
• 1/2L from bow (Rowe)

Question 4

Pivot Point - going astern moves PP…

Answer 4

moves aft

Question 5

Pivot Point - stopped and using bow thruster

Answer 5

a beam width from stern
(Hooyer)

Question 6

Pivot Point - Trim

Answer 6

• strong effect (Hooyer pg 23)
• by the head = moves aft
• by the stern = moves forward

Question 7

Pivot Point - turning hard from DIW
(Hooyer vs. Rowe)

Answer 7

• 1 / (L/B) ratio of L from bow (Hooyer)
• 1/8L from bow (Rowe)

Question 8

Pivot Point - newly introduced forces

Answer 8

• do not have immediate effect on PP until momentum subsides
• PP moves gradually (Hooyer pg 23-24)

Question 9

Pivot Point - effect of shallow water with headway

Answer 9

• Rowe says it moves aft
• Hooyer says it moves aft as well, esp. larger ships with a pronounced bow wave

Question 10

Pivot Point - ship with headway and tug pushing at shoulder

Answer 10

PP moves aft (Henson pg 43)

Question 11

Pivot Point - ship with headway and tug pushing at quarter moves PP…

Answer 11

PP moves forward (Henson pg 43)