Ships of the seven seas

by Hawthorne Daniel

An American liner, formerly a German ship. She was taken over by the United States during the World War.

Necessarily, in operating ships of such size as these we are discussing, any wasteful methods would be very expensive. It is open to some question as to whether these huge ships are worth what they cost, for the margin of profit they show is very small, and the cost of operation and repair is huge.

In order, therefore, to make them pay it is vitally necessary to eliminate waste. For instance, if the turbines were each operated by steam direct from the boilers, and this steam were sent direct to the condensers after having passed only once across the vanes of a turbine, it would take very nearly four times as much steam, and four times as much fuel, to operate the Majestic as it does with the system that is installed. Only part of the power of the steam is used up in the first turbine through which it passes, so when the ship is at full speed, the steam, still under comparatively high pressure, although much less than when it left the boilers, is led from the first turbine, which is called the high-pressure turbine, to a second turbine, called the intermediate. Here again it fans the vanes and the turbine revolves, but once more the steam is used, for part of its power still remains. This time, however, the pressure is much less, and the steam has expanded until it takes up more space than it took up in the boiler, just as the air in the rubber bladder of a football would take up more room if the leather cover which keeps it compressed were removed, or the inner tube of an automobile tire would expand if the “shoe” or “casing” were not around it. This expanded steam is divided, when it comes from the intermediate turbine, and is led to the two outside turbines—that is, the turbines that operate the port, or left hand, and the starboard, or right-hand, propellers. These are the low-pressure turbines, and when the steam has passed through these turbines, causing them to turn, its work is done and it is led to the condenser.

Condensers are a vital part of every sea-going steamship’s equipment. Locomotives do not need them, and stationary engines ashore do not, for they can easily replenish their supply of water, but to a ship crossing the ocean, fresh water is a vital necessity, for its boilers no less than for its passengers and crew, and should the used steam be allowed to escape, the ship, no matter how great her water tanks might be, would probably run out of fresh water long before her voyage could be completed, if it happened to be at all long. If, in such a predicament, she should attempt to use salt water there would very soon be a heavy covering of salt inside her boilers and her steaming ability would become limited, and, furthermore, the boilers would very shortly require a thorough cleaning.

In order to prevent this difficulty from arising, all salt-water steamships and many that are used on fresh water, for lakes and rivers often contain sediment that would foul the boilers, use condensers. These are water-cooled systems of pipes through which the steam is led after its final release from the engines. The steam, which of course is still hot, is led through these carefully cooled pipes, and in coming into contact with the cool walls of the pipes is condensed, just as the moisture in your warm breath is condensed in the winter when you breathe against a cold window pane. This condensation turns the steam into water once more, and it is led back to the tanks where it is held in readiness to be sent again to the boilers.

The auxiliary machinery of such a ship as the Majestic or the Leviathan is even more complicated than, although not so powerful as, the engines which drive the propellers.

I have mentioned the ventilation system of the stokehold, but that is only a small part of the system that ventilates every nook and cranny in the whole huge structure. There are refrigerators, which are capable of keeping in cold storage large quantities of perishable products. There is even, on the Majestic, a second refrigerating plant intended to cool a cargo hold in order that perishable freight may be carried. Another important auxiliary machine on the Majestic is a Diesel engine for generating electricity in case something might put the main generating plant out of commission. With this emergency plant, power is assured for lighting and for lowering the lifeboats.

In order to handle so great a ship when the engines are necessarily at such a distance from the “bridge” where the officer in command has his post when the ship is under way, it is necessary to have some means of communication between the bridge and the engine room.

A person driving an automobile is not only in command of the steering of the machine, but is also in direct charge of the engine, the gears, and the brakes. Not so the captain of a ship. Neither he, nor any of the men with him on the bridge, has any means of starting or stopping the engines. There is a man at the steering wheel, of course, but the men who start and stop and reverse the engines are far below the bridge and far aft, hidden away beyond where any shouted orders could possibly reach them. Yet the engines must be operated as the captain commands, for he is the man who can see what must be done—he is the one upon whose judgment the safety of the ship depends.

In order to bridge the gap between the bridge and the engine room an apparatus called the “engine-room telegraph” has been perfected. There are a number of designs, but all of them by simple mechanical means permit the officer on the bridge to operate a handle and set a hand on a dial placed in the engine room so that it signifies the officer’s orders.