DCASE Unit 2
What are the conditions of critical stability? - ANS-a) Floodable length exceeded.
b) Neutral or negative GM.
c) Listing to the danger angle (1/2 max righting arm (GZ)).
d) Damage with bad weather.
What is the displacement? - ANS-The weight of the volume of water displaced by the
hull at the waterline (expressed in LT)
What are the stability Reference points? - ANS-M - Metacenter
G - Center of Gravity
B - Center of Buoyancy
K - Keel
*Mother Goose Beats Kids
As the waterline/draft increases, the buoyancy __________. And as the waterline/draft
decreases, the buoyancy ___________? - ANS-Increases, decreases
B follows the waterline
Adding weight ________ draft.
Removing weight ________draft. - ANS-Increases, decreases
If a weight is shifted down, G moves ___________.
If a weight is shifted up, G moves ___________. - ANS-Down, Up
G follows a weight shift
G moves _________ weight additions and moves __________ weight removals. -
ANS-towards, away from
As B moves up, M moves ______. - ANS-Down
M moves opposite of B
What is the range for initial stability? - ANS-0-10 degrees
, What is a permanent list? - ANS-A permanent angle of inclination
What are three conditions that can cause a ship to take a permanent list? - ANS-a) G off
center line
b) Negative GM
c) combination of both
What is heel? - ANS-A semi-permanent angle of inclination caused by external forces
(e.g., high speed turns, beam winds, heavy seas)
What are the three conditions of stability and how are they defined? - ANS-a. Positive -
G is below M; Righting moments
b. Neutral - G is equal to M; No moments because no distance btw G and M to create a
moment
c. Negative - G is above M; Upsetting moments
What are four things to keep a ship afloat? - ANS-1. Follow LLI (Liquid loading
instruction)
2. Maintain WTI (Watertight integrity)
3. Do not submerge limiting draft marks
4. No abnormal topside weights
What is a good measure of initial Stability? How is it calculated? - ANS-GM
GM = KM - KG
What is the reference point for initial stability? Which reference points affect it? - ANS-M
- Metacenter
Affected by B and G, because it is the intersection of the lines of these forces.
What is the GZ? - ANS-Righting Arm = the perpendicular distance between the center
of gravity and center of buoyancy
What is the max righting arm? - ANS-point where ship exerts the most energy to right
itself
What are the conditions of critical stability? - ANS-a) Floodable length exceeded.
b) Neutral or negative GM.
c) Listing to the danger angle (1/2 max righting arm (GZ)).
d) Damage with bad weather.
What is the displacement? - ANS-The weight of the volume of water displaced by the
hull at the waterline (expressed in LT)
What are the stability Reference points? - ANS-M - Metacenter
G - Center of Gravity
B - Center of Buoyancy
K - Keel
*Mother Goose Beats Kids
As the waterline/draft increases, the buoyancy __________. And as the waterline/draft
decreases, the buoyancy ___________? - ANS-Increases, decreases
B follows the waterline
Adding weight ________ draft.
Removing weight ________draft. - ANS-Increases, decreases
If a weight is shifted down, G moves ___________.
If a weight is shifted up, G moves ___________. - ANS-Down, Up
G follows a weight shift
G moves _________ weight additions and moves __________ weight removals. -
ANS-towards, away from
As B moves up, M moves ______. - ANS-Down
M moves opposite of B
What is the range for initial stability? - ANS-0-10 degrees
, What is a permanent list? - ANS-A permanent angle of inclination
What are three conditions that can cause a ship to take a permanent list? - ANS-a) G off
center line
b) Negative GM
c) combination of both
What is heel? - ANS-A semi-permanent angle of inclination caused by external forces
(e.g., high speed turns, beam winds, heavy seas)
What are the three conditions of stability and how are they defined? - ANS-a. Positive -
G is below M; Righting moments
b. Neutral - G is equal to M; No moments because no distance btw G and M to create a
moment
c. Negative - G is above M; Upsetting moments
What are four things to keep a ship afloat? - ANS-1. Follow LLI (Liquid loading
instruction)
2. Maintain WTI (Watertight integrity)
3. Do not submerge limiting draft marks
4. No abnormal topside weights
What is a good measure of initial Stability? How is it calculated? - ANS-GM
GM = KM - KG
What is the reference point for initial stability? Which reference points affect it? - ANS-M
- Metacenter
Affected by B and G, because it is the intersection of the lines of these forces.
What is the GZ? - ANS-Righting Arm = the perpendicular distance between the center
of gravity and center of buoyancy
What is the max righting arm? - ANS-point where ship exerts the most energy to right
itself
