Two hydroplanes mounted at the aft in the vertical plane are used to change the lateral direction of the submarine when in motion. The hydroplanes or fins are shown in Figure 8. A pair of hydroplanes or fins at the forward and aft are used to control the heave and pitch independently. Unlike a surface ship, submarines are subjected to lesser heave and pitch motions due to the absence of surface wave effects. To understand the application of hydroplanes, we first need to know the nature of motions experienced by a submarine in submerged condition. When the submarine is in submerged condition, changes in direction and depth is carried out by use of hydroplanes that act as control surfaces. It is very important to keep the drag within limits as it prevents eddies and subsequently, minimises the acoustic signature of the submarine. This shape reduces the drag on the submarine. The profile of the bridge fin in a submarine design is always an aerofoil shape, as it acts as a hydrofoil with the submarine sails with just the fin above water. Figure 7: Bridge Fin or Sail in a submarine. Figure 7 shows the sail in a submarine when the masts are not deployed. These are raised from the bridge fin when the submarine requires surface monitoring in stealth mode. The different masts used in a submarine are periscope mast, communications mast, radar mast, weapon sensor mast, etc. Its different types of masts that are deployed from within the submarine when snorkels or sails just under the free surface. The sail is the streamlined shaped non-pressure resistant part of the submarine over the outer hull. Figure 3: Exposed Pressure Hull (MBTs at forward and aft).įigure 4: Enclosed Cylindrical Pressure Hull (MBTs throughout the length).įigure 5: Waisted Pressure Hull (MBTs at certain parts of the length).įigure 6: Exposed pressure hull reduced at ends (MBTs at forward an aft). Some arrangements of MBTs are shown in the figures below. Other designs have completely different outer and pressure hull, with space for ballast between them. Some designs have MBTs only at the forward and aft regions, and the rest of the pressure hull is flushed with the outer hull. We will understand the working of MBTs after we deal with the process of submerging a submarine, and submarine stability. The distribution of main ballast tanks in a submarine depends on the shape and interaction of the outer and pressure hull. Now, the “floodable” spaces are compartmentalised into tanks, which in submarine terminology, are called Main Ballast Tanks. Hence, the hydrostatic pressure on the outer hull is negligible. Why? Because, in submerged condition, the spaces between the outer and the inner hull always remain flooded with seawater. The pressure hull is housed inside the outer hull, which is not pressure tight. Figure 2: Cylindrical Pressure hull and Outer hull of a submarine. It is called the pressure hull because it is designed to withstand the hydrostatic pressure at the maximum operable depth of the submarine. The hull that houses all the accommodation spaces, weapons, weapon control systems, communications and control room, battery banks, main and auxiliary machinery, is the pressure hull. Most designs of submarines have two hulls.

The cost of the project should be acceptable to the customer.

The design should be capable of being constructed with available resources.The submarine should cater to the functional purpose of the customer.The primary submarine design objectives are:

Though the design process followed by all navies is confidential and different from each other, the basics still remain the same. Once we have looked into these, it would be easy for us to touch on the submarine design process. In the first few articles of this series, we will not go into the design process, rather, we will familiarise ourselves with the design and functionalities of a submarine, its parts, general arrangement, structural design and arrangement, the stability of a submarine, the systems used in a submarine, etc. In this series of articles, we will study the design of naval submarines. This, though, is a very simple description of a very complex engineering product, which are used for a wide range of purposes such as underwater research, underwater rescue, and submarine warfare the last one being the most widely used. The submarine design consists of a single or double-hull system that houses all the necessary systems and manpower required for completion of their mission. Submarines are underwater self-propelled crafts that are designed and built to perform underwater operations for a stipulated amount of time.

Fast personal submarine