Class 4 (4th Engineer) SC&S 📅 Sep 2022

Exam Question

Describe the arrangement of tank top and double bottom in the machinery space making particular reference to the structure and scantlings below the main engine. Show the method adopted in the arrangement of D.B. tanks to avoid contamination of fresh water, fuel oil and lube oil stored in D.B. tanks. (16)

Reference Answer

### **1. Introduction**
The double bottom in a ship's machinery space serves a dual purpose: it forms an integral part of the ship's primary structure, contributing to longitudinal and transverse strength, and it provides segregated tankage for various consumables such as fuel oil, lubricating oil, fresh water, and other service fluids. The structure in this area is significantly reinforced compared to other parts of the ship due to the immense static and dynamic loads imposed by the main propulsion machinery, auxiliary equipment, and the thrust block.
### **2. Structural Arrangement and Scantlings Below the Main Engine**
The construction under the main engine is exceptionally robust to provide a rigid, vibration-resistant foundation capable of absorbing operational forces and maintaining critical shaft alignment. The key features are as follows:

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