Stability

Question 1

Archimedes’ Principle

Answer 1

A ship that floats will be subject to an upward thrust equal to the weight of the immersed volume of water displaced

Question 2

Draft / Displacement questions

Answer 2

1. a draft can be found with a known displacement
   (D -> T)
2. a displacement can be looked up with a known draft
   (T -> D)

Question 3

Plimsoll mark

Answer 3

Load line: through 300 mm circle (= Summer draft)

Freeboard line: above the mark, indicates height of freeboard deck

Question 4

Calculating KG

Answer 4

Question 5

Stability moment and GM

Answer 5

Question 6

KM/KG/GM

Answer 6

KG: can be calculated in table of moments
(SUM weights * KG = SUM moments)

KM: for every draft in hydrostatic tables
(KMT = KM transverse = KM0)

Question 7

Rules for minimum GM

Answer 7

Question 8

Calculate the movement of GG’ when shifting stuff on board

Answer 8

horizontally (inclining test) and vertically (loading/lifting)

Question 9

Inclining test

Answer 9

Question 10

Requirements for inclining test

Answer 10

Question 11

Free surface effect

Answer 11

Question 12

Relationship
roll period (T) and beam (B)

Answer 12

Question 13

Roll period T:
rule of thumb

Answer 13

between 3/4 and 4/3 B

Question 14

Stability curve

Answer 14

Question 15

Narrow / Broad Ship
Stability Curves

Question 16

Stability Rules

Answer 16

1. initial stability GM0 min 0.5 m
2. max GZ at angle min 30 deg (never <25)
3. GZ min 0.2 m at angle min 30 deg

Question 17

FSM
calculate i

Answer 17