Friday, January 25, 2013

Captain's Blog 1/28/13

Today's Captain's Blog is written by Captain Brad Lima, Vice President of Academic Affairs, and a licensed Chief Engineer.

I have the opportunity to observe the on watch deck and engine cadets maneuver the Kennedy down the Mississippi. Speed changes rang out from the river pilot on the bridge which set in motion a series of orders and commands, each which must be followed to a specific level of detail. The deck cadets all reacted in harmony with deliberate concentration as they send a speed change to the engine room via an engine order telegraph. The engineers respond to the 'bell' by manually controlling the volume of steam to the main engine. The engine cadets manipulate the throttle valve while other cadets ensure the combustion rate makes enough steam to support all systems. It was refreshing to see the cadets focused on a specific task with positive results knowing that there are consequences if they fail to perform the task with precision.

The engineering plant onboard Kennedy has two 600 PSI boilers producing steam which is sent to the main engine, generators for electricity, as well as many auxiliary systems. The main engine is direct-geared to the propeller which propels the vessel. There is a long shaft which connects the gears and the propeller located in 'shaft alley'. As the cadets make their inspection rounds they can see the propulsion shaft turn which has been painted like a candy cane. The ship also has a large diesel generator which can handle the entire ships' electrical load.

While it is important to keep the engine turning, there are auxiliary systems which require equally close attention. The ship has two air conditioning plants which provide cool treated air to the living quarters and galley since there are no windows that can be opened onboard this vessel. Refrigeration is another separate system which keeps refrigerated all the food loaded in Buzzards Bay. Our refrigerators have walk-in boxes that are designated as freeze (bellow 32) or chill (above 32).

With over 700 onboard the vessel, water is precious. Water is necessary for cooking, cleaning and the boiler. Fresh water can be produced by one of two methods. One is a distillation process where salt water is boiled under low pressure and the steam is condensed resulting in very pure water. The other method is through reverse osmosis where water is pumped at very high pressure through membranes which filter the salt from the water. Water from the reverse osmosis system cannot be used in the boilers.

Here is an applied engineering math question:

A gallon of sea water weighs 8.5 pounds. The density of salt in sea water is 1/32. The purity of sea water when distilling is completed is less than one grain (7000 grains equals' one pound). How many grains of salt are in one gallon of sea water?

No comments:

Post a Comment