Ship Resistance

1. Introduction to Ship
Resistance and
Propulsion

2. Tahanan Kapal (RT)
Besarnya gaya yang harus diatasi untuk menggerakkan
kapal pada kecepatan Vs
Vs
Vs
RT

3. COMPONENTS OF RESISTANCE

5. Resistance….(Holtrop 1984)

6. Resistance
( )
[ ] W
W
R
C
k
C
S
V
R W
A
F
tot
T +
+
+
×
= 1
2
1 2
r
1. Appendages resistance (hambatan badan
kapal dan tambahan/ aksesoris kapal)
2. Friction Resistance (Hambatan Gesek)
3. Wave making resistance (hambatan
gelombang karena gerak kapal)
4. Air Resistance
5. Eddy Resistance
……(PNA Vol.II)
Another Popular Typical of Additional
Resistance is 15 % of Total Resistance
Sea Margin

7. Resistance
( )
[ ] W
W
R
C
k
C
S
V
R W
A
F
tot
T +
+
+
×
= 1
2
1 2
r
Friction Resistance
Wave making Resistance
Appendages Resistance
Transom & Bulbous
Bow Resistance
1+k1
1+k2

8. COMPONENTS OF RESISTANCE

9. TOTAL RESISTANCE

10. Eddy making Resistance
There would be a pressure drop and might go negative. This means that the flow
will separate and cause formation of eddies. This is called Separation
resistance or Eddy drag.
Main contribution to the form resistance is made by eddy-making resistance.
For a low speed ship, it is important to avoid the abrupt change of the hull in
order to minimize the eddy-making resistance.

12. Spray resistance
Spray is a phenomenon that occurs on high-speed marine vehicles (including
semi-displacement vessels, planing craft and hydroplanes) when they operate at
high speeds. It is created from the stagnation line (a line that separates the flow
going under the hull from the flow going into the spray area) and it forms a thin
sheet of fluid along the bottom surface above the stagnation line – which, under
low-speed operation, would have been dry
The added resistance accounts for 15-18% of total resistance at higher speed [1].
As the speed increases, the ratio of added spray resistance to the total resistance
increases.

15. Propulsive Efficiency
• Relative Rotation Efficiency (ηrr)
For single screw ship = 1.0 – 1.05
• Open water Efficiency (ηo)
40 – 70 %
• Hull Efficiency (ηH)
η H = (1-t)/(1-w)
• Propulsion Coefficient (Pc)
Pc = ηrr x ηp x ηH

16. Vs
Vs
RT
THP DHP SHP BHP
EHP = Vs x RT
EHP
hG
hs
PC
PC = EHP / DHP
Propulsive Coefficient
hH = EHP / THP
Hull Efficiency
= (1-t) / (1-w)
EHP : kW
Vs : m/s
RT : kN
hB = hO x hR =
THP / DHP T
RT
VA Advance Velocity
THP = VA x T
T measured in a propulsion test
RT measured in a resistance test (without propeller)
T (1- t) = RT
Vs (1- w) = VA
t : thrust deduction fraction
w : wake fraction
= hH x hO x hR
Relative
Rotative Eff
EHP

17. EFFICIENCIES
G.4 Perhitungan efisiensi Rotative, hR
(ref : Ship Resistance and Propulsion, Modul 7, hal.2)
hR = 0.970

18. HULL EFFICIENCY

19. PROPULSION SYSTEM
TRANSMISSION SYSTEM
Ps = PD / ɳS
PB = PS / ɳGB
ɳProp = PT / PD
ɳs = PD / PS
ɳGB = PS / PB
PD = PE / pc

20. ENGINE–PROPELLER MATCHING

21. ENGINE–PROPELLER MATCHING

22. PROPELLER REQUIREMENT
- Propeller Design is < Dmax
- Sufficient Hull Propeller Clearance
- No Cavitation
- The Most Efficient
- Propeller Thrust > Required Thrust

23. BURRIL DIAGRAM
τc > τc‘ = no cavitation occur
tan
2
1 2
kons
gh
v
P =
+
+ r
r
2
2
1 2
2
1
2
1
2
1
v
P
v
P r
r +
=
+
)
(
2
1 2
2
1 1
2
2
2 v
v
P
P
P -
+
=
- r

24. HULL PROPELLER CLEARANCE

25. KT, KQ, J diagram (Open Water)

26. 26
Sistem Propulsi Keuntungan Kerugian
FPP - Instalasi & Perawatan Lebih Mudah - Manuver terbatas
- Biaya Investasi & Operasional Rendah
SRP - Manuver lebih baik
- Biaya investasi dan operasional sangat tinggi
- Sistem lebih kompak
CPP - Daya Dorong Besar
- Biaya investasi dan operasional sangat tinggi
- Manuver terbatas
PROPULSION SYSTEM COMPARISON
Propulsi FPP Propulsi SRP Propulsi CPP