W3_DI_VESSEL SPEED PROBLEM

1.    Problem recognition, definition and evaluation

Last time in the Lombok strait at 05:00 LT, there has been damage on Vessels X’s main engine. After investigation founded that the root of the problem is in the turbocharger lubricant system. The lubricant system did not work properly, so it makes shaft and ball bearing overheating and cause some damage on rotor (shaft, turbine and compressor wheel), backplate, and ball bearing.

 Figure 1. Cut view Turbocharger

In order to restore vessel speed performance, ship manager need to fix this turbocharger main engine problem.

2.   Development of the feasible alternatives

After doing discussion and evaluation, we decide three options to fix this problem, as follows:

-          Option 1: Repair with machining rotor and replace broken parts using 2^nd class part.

-          Option 2: Repair with replace rotor and broken parts only using genuine part.

-          Option 3: Replace with the new turbocharger unit

 

3.       Development of the outcomes

 The detail information for each option as in table below:

Option 1

Option 2

Option 3

4.     Selection of the acceptable criteria.

Concern of Ship manager is to comply with Vessel X’s Financial KPI, this mean that we will choose the option with best NPV.

5.      Analysis and comparison of the alternatives

Comparison of the three options using the PW Method with MRR 12%, calculations for each option are:       

PW1                 : -75,000 – 35,000(P/A, 12%, 5) + 10,000(P/F, 12%, 5)

                        : -75,000 – 35,000(3.605) + 10,000(0.5674)

                        : -75,000 – 126,175 + 5,674

                        : - 195,501

PW2                 : -120,000 – 30,000(P/A, 12%, 5) + 30,000(P/F, 12%, 5)

        : -120,000 – 30,000(3.605) + 30,000(0.5674)

                        : -120,000 – 108,150 + 17,022

                        : - 211,128

PW3                 : -200,000 – 15,000(P/A, 12%, 5) + 75,000(P/F, 12%, 5)

        : -200,000 – 15,000(3.605) + 75,000(0.5674)

                        : -200,000 – 54,075 + 42,555

                        : - 211,520

6.     Selection of the preferred alternative

Based on our calculation the repair option 1 is the best result. So we will repair turbocharger with re-machine rotor and replace broken parts with 2^nd class part.

7.      Performance Monitoring & Post Evaluation of Result

The repair with option 1 takes total six day repair time. The speed of Vessel X is 11.5 knots which mean that she meet her KPI and everyone will happy.

Reference: 

         i.    William G. Sullivan, Elin M. Wicks, and C. Patrick Koelling (2011), Engineering Economy (15^th Edition), Chapter 6 (p.226-p240)

       ii.     Using turbocharger for a jet engine, retrieved from: 

http://www.salvatoreaiello.com/main.shtml

      iii.    Purdue online writing lab. Reference List: Electronic Sources (Web Publications). Retrieved from :

http://owl.english.purdue.edu/owl/resource/560/10/