Ship Stability Teacher’s Manual - Old Dominion …averma/nsf/Marine Kits/Ship Stability...Ship Stability . Teacher’s Manual. Contents • Teacher’s Instructions • Assessment

Ship Stability Teacher’s Manual

Contents

• Teacher’s Instructions

• Assessment Sheet

• Students Handouts

• Work sheets

• Answer Key

Marine Kit – 3

This activity was developed under a grant from National Shipbuilding Research Program (NSRP)

SBRCD SHIP STABILITY

Teacher’s Instructions This activity deals with the effect of center of buoyancy on ship’s stability, finding the weight of displaced water by foam model and comparing the draft of model in saline and fresh water. Kit Contents

• The kit contains a foam model, ruler, weights (washers-16), and a marker. • Students additionally need calculator, water and salt.

Set Up • This activity requires two class periods. (Day – 1 and Day – 2) • Answer key is included in the kit for the teacher.

Day – 1 • Please use the power point presentation for day -1 activity. (10 to 15 min) • Identify 3-4 students to help you with the activity. • Day-1 activity involves finding center of buoyancy and weight of displaced

water.( 40 – 45 min) • Work sheets are provided in the kit for calculations. Make additional copies of

student worksheets as needed. • Foam models are delicate. Students should be cautioned not to pierce or damage

the foam models during the experiment. • At the end of activity, please wipe the foam model and the tank. Collect all parts

and place them back in the box. • Markers are provides to mark the location of center of buoyancy. Please ask

students to wipe the mark using moistened paper towel so that next group of students can repeat the experiment.

Day – 2 • Please use the power point presentation for day - 2 activity. (10 to 15 min) • Identify 3-4 students to help you with the activity. • Day-2 activity involves comparison of draft in fresh and saline water. (40 –

45min) • For the second day, salt packet is provided. Salt must be dissolved uniformly in

the water. • At the end of the activity, please wipe the tank completely and remove any

remaining salt. • Check the kit contents for any missing or damaged part and put the contents back

in the box. • Use the assessment sheet to assess the performance of each group. MarineTech Project Ship Stability Lean Institute, ODU August 2008

1

Group No:

Names

1)

2)

3)

4)

Poor Fair Good Very Good Excellent

Quality Characteristics 1 2 3 4 5

Was the water filled to the accurate level?

Was the center of bouyancy correctly marked?

Is the volume of the water displaced correctly calculated?

Is the weight of the water displaced correctly calculated?

Was the understanding about the effect of salinity on the buoyancy adequate

Date(mm/dd/yy):

Ship Stability Assessment Sheet

This assessment sheet is to be used to evaluate of Stability calculations

MarineTech Project Ship Stability Lean Institute,ODU AUG 2008

Total Points

MarineTech projectAlok K. Verma 08/08

SHIP STABILITY

STUDENT HAND OUTS

Marine Kit – 3


Day 1: Part - A, Center of Buoyancy ( CB)

1. Fill the tank with water till

marked line. Place the model in

the tank. Check the level of

model from all sides.

2. Place the weight (three washers)

on foam model at any point and

check whether model is level with

water line.

Model not parallel to water level


Day 1: Part - A, Center of Buoyancy (CB) ( Contd.)

3. Move the weights until the

foam model is level with respect

to the water line.

4. Mark the circle inside washer

with a pencil. Remove the

washers and take the foam

model out of tank.

Model parallel to water level


Day 1: Part - A, Center of Buoyancy (CB) (Contd.)

6. Note down the X and Y

coordinates of the CB on

X-Y grid of the model.

5. Mark the center of circle

as CB.


Day 1: Part – B, Weight of Displaced Water

7. Place the foam model in

the water tank. Check the

level of model from all sides.

8. Place weights at the CB until the

model is submerged such that only

top surface remains above water.

(Make sure there is no water on top

surface). Count the washers.

Water Level


Day 2 : Effect of Salinity

1. Fill the water till marked

line. Mix two cups of salt in

the tank.

2. Place the same number of

washers at the CB (as in the

previous experiment), and

observe the change in draft.

Water Line

Water Level Level difference in red lines

indicate the draft change


Work Sheet

1. h1 = cm, h2 = cm, b1 = cm

2. A1 = 0.5 * h1 * b1 = sq.cm

3. A2 = h2 * b1 = sq. cm

4. Area = A =A1 + A2 = sq. cm

5. Thickness of foam model = cm

6. Thus, Volume(V) of water displaced by the model :

V = A * Thickness = cu. cm

7. Weight of water displaced by the model

( Density of water = 1000 kg/m3 )

= Volume * Density of water

= kg b1

h2

h1A1

A2


Work Sheet ( Contd.)8. Coordinates of Center of Buoyancy: XB = cm, YB = cm

9. Number of washers required to find weight of displaced water = N =

(Weight of each washer = 0.030 kg or 0.041 kg)

10. Weight of washers = N * = kg

(Compare the answers for weight of washers and the weight of displaced water. Are they equal ? )

Note: You can either have washers of Type-1 / Type-2 in your Kit.

Type-1 Type-2

Outer Diameter (O.D) = 50 mm Outer Diameter (O.D) = 44 mm

Inner Diameter (I.D) = 21 mm Inner Diameter (I.D) = 18 mm

Weight = 0.041 kg Weight = 0.030 kg

Answer key for Work Sheets

Marine Kit - 3

SHIP STABILITY

This activity was developed under grant from National Shipbuilding Research Programme(NSRP)

Marine Tech Project Shipyard Operations Lean Institute, ODU August 2008

1

Ship Stability Answer Key

1. h1 = 7.6 cm, h2 = 17.7 cm, b1 = 12.7 cm

2. A1 = 0.5 * h1 * b1 = 48.26 sq.cm

3. A2 = h2 * b1 = 224.79 sq. cm

4. Area = A =A1 + A2 = 273.05 sq. cm

5. Thickness of foam model = 1.90 cm

6. Thus, Volume(V) of water displaced by the model :

V = A * Thickness = 518.795 cu. cm

7. Convert units from cu. cm to cu. m

1cu. cm = 0.000001 cu. m

521.21 = 0.00052 cu. m

b1

h2

h1A1

A2

2

Answer Key ( Contd.)8. Weight of water displaced by the model

( Density of water = 1000 kg/m3 )

= Volume * Density of water

= 0.52 kg

9. Coordinates of Center of Buoyancy: XB = 6.6 cm, YB = 11.5 cm

10. Number of washers required to find weight of displaced water = N = 12 or 17

(Weight of each washer = 0.030 kg or 0.041 kg)

11. Weight of washers = 12 * 0.041 = 0.492 kg

OR

Weight of washers = 17 * 0.030 = 0.51 kg

(Compare the answers for weight of washers and the weight of displaced

water. Are they equal ? )

Ship Stability Teacher’s Manual - Old Dominion …averma/nsf/Marine Kits/Ship Stability...Ship Stability . Teacher’s Manual. Contents • Teacher’s Instructions • Assessment

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