Engineering Cadet Assignment: Looking for some knowledge

[millstr]

Hey guys,
I have assignment to do for the Technical Communications course this semester and I am hoping someone might have some ideas to help me out. For the assignment I have to write a formal report on a scenario I picked from a hat. The scenario says: "You have been asked for an explanation why your vessel's fuel consumption is significantly higher and its average sea speed correspondingly lower than that of a sister vessel. As Cheif Engineer, make a report to head office giving a full explanation for discrepancy".

Any creative ideas?

[JK]

LOL
You have a standard 1st class ticket general question.
Of course we know the answer. Tell you what, give it some thought and come back and post what you think would make a ship use more fuel and we can guide you further.
Think of the ship as a whole, the cargo, area of deployment, the last docking and so on.

[millstr]

well....
I suppose if you interpret the question for the ship as a whole there is many things that would increase fuel consumption. The weight of the cargo the vessel is carrying obviously has an effect on its fuel consumption, aswell as weather conditions and currents. The location could also possibly play a role in both fuel consumption and average speed. In theory, a vessel on the Great Lakes would show differences in fuel consumption and average speed to that of a vessel in the Atlantic. Am I on the right track? A discrepancy during the fueling of the vessel could also present a percieved increase in fuel consumption I suppose. There is countless variables that would effect both fuel consumption and average speed, so many that it would be very difficult to gather an accurate comparison unless the differences were significant.

[Big Pete]

Welcome to the site,
You are on the right lines, keep the ideas coming. You should be able to come up with a few more.
A clue for one:-
Why are speed record attempts usually made at Dawn?

We are not being hard, but there is no point in "spoon feeding" you the answers, it is far better to help you work out things for yourself.

[JK]

Remember, it is a technical report, so that means you have to present it in a specific format. Was that covered in your class?

[alanocean]

Onw word to also help with idea's.... "Friction" inside and out!

[Big Pete]

Hi Milstr,
Did you get your assignement finished?

You were looking in the right direction when you were talking about the whole ship.
Now you have had some time to think, and because no one else has come forward with any pointers for a while, I'll give you some more.
If I ever run into you in a bar they will cost you a beer!!

The question is about the relationship between fuel input and speed/distance output, i.e. efficiency.
1) )Same quantity of bunkers may not mean the same quantity of energy:-
a) water & sludge content
b)Calorific value
c) Combustion characteristics, e.g. Cetane Number (like Octane numbers only for diesel fuels, and while high Octane petrol is hard to ignite, high Cetane fuel is easier to ignite)
d) Purification/settling process are purifiers dumping good oil along with the water & sludge?
e)Did the Bunker supplier supply less fuel than ordered causing discrepancy in fuel figure? One old trick is to open an air cock on the bunker pump suction so that the fuel is aerated and the soundings taken on board, and the flow meter readings then include the volume of air bubbles, days or even weeks later the air bubbles work their way to the surface and escape you suddenly have a shortfall in your bunkers.

2)Efficiency of the machinery in converting the chemical energy in the fuel into mechanical shaft power.
a) State of repair of machinery
b)Correct set up eg fuel injection timing, governors, correct temperatures & pressures, clean air cooler/filters adequate ventilation to engine room, fuel/air ratio for boilers etc.
c) Ambient conditions, air temperature, pressure, humidity all effect engine efficiency.

3) Use of energy for auxiliary purposes.
a) Accommodation heating/cooling on passenger ships in hot or cold weather not required in temperate areas.
b)Cooling Refrigerated cargoes, when carried
c)Cooling Liquid gas cargoes, when carried
d)Heating cargoes such as Tallow, Palm Oil, Bitumen, Pitch, Black oils etc.

4)Efficiency of propeller in converting shaft power into thrust.
a) Prop. clean & undamaged?
b)ship operating at best design trim & draft.
c)Weather, heavy seas may cause prop to come out of the water

5) Hull Efficiency
a)Damage to Hull (increased drag)
b)Fouling of hull
c)Ship operating at best design trim & Draught.
d)Weather.
e) Towing a dracone, barge , another vessel or structure.
f)Operating in Ice!!
g)Operating in shallow water, causes "squat" and increased drag, lower speed & higher fuel consumption.

6)Steering
a)Autopilot set up correctly
b)Rudder and steering gear operating correctly
(You will burn more fuel, for less speed when the rudder is not in midships and your distance "made good " will be less than the distance you have made through the water if the ship is zig zagging all over the Ocean.)

7)Effects of Tides, Ocean Currents and wind.

That is all I can think of, I ams ure some one else will point out a few more!!, But it is plenty for a Cadet level answer.