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Ship Shafting Design Analysis

The document summarizes the calculation of key parameters for a ship's shafting arrangement, including: 1) Propeller RPM of 413 based on the engine speed of 1032 RPM and gear ratio of 2.5. 2) Torque of 30.626 Nm calculated from the engine power of 1324 kW. 3) Propeller shaft diameter of 168 mm determined using the rules for classification of ships and factors like power, speed, material strength. 4) Polar moment of inertia of 0.00007789 m4 for the shaft. 5) Twisting angle of 0.001769 degrees calculated from the torque, shaft length, moment of inertia and shear modulus.

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mohammad shihab
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479 views4 pages

Ship Shafting Design Analysis

The document summarizes the calculation of key parameters for a ship's shafting arrangement, including: 1) Propeller RPM of 413 based on the engine speed of 1032 RPM and gear ratio of 2.5. 2) Torque of 30.626 Nm calculated from the engine power of 1324 kW. 3) Propeller shaft diameter of 168 mm determined using the rules for classification of ships and factors like power, speed, material strength. 4) Polar moment of inertia of 0.00007789 m4 for the shaft. 5) Twisting angle of 0.001769 degrees calculated from the torque, shaft length, moment of inertia and shear modulus.

Uploaded by

mohammad shihab
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Military institute of science & Technology

Course Code-NAME-300
Ship Design Project & Presentation
Topic-Shafting Arrangement
Submitted By Submitted to
Name- MD. Shihab Name- SM Ikhtiar Mahmud
Imrul kayes Ibne Rahim
ID- 201924025, Asst.Professor
201924033 NAME,MIST
Batch-NAME-07 Course-Ship Design Project &
Presentation
Level-3

Date of submission 2.1.2022

Shafting Arrangement Scantling


Rulebook Followed-BV(2013)
Principal Particulars
Engine Speed (RPM) 1032 RPM
Gear Ratio 2.5
Shaft length, L(m) 6.44m

Max Tensile Stress, (MPa) 600 Mpa

Shear modulus of elasticity, G (Pa) 82 Gpa


Engine Power(1x in KW) 1324 kW

Calculation
1. Propeller RPM
We know,
1032
Propeller RPM, n= 2.5
=412.8 ≅ 413

2. Torque
Engine Power(KW )× 9.5488 1032× 9.5488
Torque,T = Propeller RPM
=
412.8
=30.626 Nm

3. Shaft Diameter
Data From Rulebook-
[From Rules for the Classification of ship 2013, BV Rule]
The diameter of the propeller shaft d P shall not be less than that
calculated from the following formula:

√
P 1 560
d P=F P ∙ k p 3 ∙ ∙

( )
n d uP 4
RmP +160 [ mm ]
1−
d vP

Where,
 F P=¿ factor for the type of propulsion installation.
¿ 100 for-
 Turbine
 I.C. Engine
 Electric Propulsion Engine
Installations
 k P=¿factor dependent on shaft design features
¿ 1.26 for-
 propeller shafts where the propeller is keyed on the
propeller shaft.
 P=¿rated power of the main engine, [ kW ]
¿ 1324 kW

 n=¿rated speed of propeller shaft,[ rpm ]


¿ 412.8
 d uP=¿diameter of internal longitudinal shaft bore,[mm]

 d vP =¿ outside shaft diameter,[mm]


 Consideration-
If d uP ≤ d vP it may be taken that:-
 1− ( )
d uP 4
d vP
=1.0

 RmP =¿tensile strength of the shaft material[N /mm2 ]


2
¿ 600[ N /mm ]

Hence we have-

√
P 1 560
d P=F P ∙ k p 3 ∙ ∙

( )
n d
4
RmP +160 [ mm ]
1− uP
d vP

¿ 100 ∙1.26
√
1324 1
3
∙ ∙
560
412.8 1 600+160
¿ 167.833 mm ≅ 168 mm
[ mm ]

∴ The diameter of the propeller shaft


d P=168 [ mm ]

4. Polar Moment of Inertia


4
π ∙D
Polar moment of Inertia, J= 32 P [ m4 ]
π ∙(0.1678)4 4
¿ [m ]
32
¿ 0.00007789[m¿¿ 4 ]¿

5. Twisting Angle
TL 30.626 × 6.4 −5
Twisting Angle,θ= GJ = 82 ×109 ×0.00007789 =3.087 × 10 [radius]

¿ 3.087 ×10−5 ×57.2958 [ degree]

¿ 0.001769 °
Calculation Summary

1.Propeller RPM, n 1032 RPM

2.Torque,T 30.626 Nm

3. Propeller shaft dia d P 168 mm

4
4. Polar moment of Inertia, J 0.00007789 m

5. Twisting Angle,θ 0.001769 °

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