two questions that i'm having trouble with for the 2nd class

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Jason
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two questions that i'm having trouble with for the 2nd class

Postby Jason » Tue Dec 14, 2010 6:50 pm

I'm currenlty studing for second class general knowledge exam. I'm looking for good answers to two questions:

(1) Sketch and describe a bile system

(2) sketch and describe a steering gear system.

i have some what of a answer for both questions but i'm not 100% sure, thank you for any help that you can give.

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JollyJack
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Re: two questions that i'm having trouble with for the 2nd class

Postby JollyJack » Wed Dec 15, 2010 5:27 am

As I have said elsewhere, APM, Thermo, Leckytech and NAR are all theory exams which benefit from study, the EKG is a practical exam, all about what you know and what you have done. If you have spent any time at all in the bilges grinding bilge valves, cleaning strum boxes, or pumping out bilges while on watch, you will have no problem. Sketch a block diagramme with the components of the system and connect them, showing flow. Don't forget the OWS monitor and SDNR valves! EK is Engineering Knowledge, all about what you have done, not about what you have read.

Same with a sketching a steering system. If that's all the question is, draw a tiller and rudder on a rowboat. That's a steering system. If, however, if it asks for an electro-hydraulic steering system, draw the one you know, what you have worked on, explain how the pump works, how the rams operate, what happens when the rudder is hit by a wave, what hunting gear is, how the telemotor works, how feedback is provided to the bridge. The Examiner is making sure you know enough that you won't do too much damage and won't kill anyone.

Concentrate on what you know, not on what you have to study to pass. "Study" should be on Exam technique, how to organize your knowledge, and this has been extensively covered in other topics here by JK and others. If you have to study subject matter, you shouldn't be writing the exam, get some more experience and pay attention to what you are doing this time. An experienced Engineer should be able to write the EKs cold, with no preparation, and have a reasonable prospect of passing them. (Yes, there are precedents.)

There's a reason you need a total of 60 months qualifying service to write 2nd Class, by that time, you should have enough experience on ships to know what you are doing. If you have the experience and the knowledge, go for it. If you don't, don't waste your time and money.

When writing the Exam, the guiding principles are K.I.S.S. and R.T.F.Q.
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Re: two questions that i'm having trouble with for the 2nd class

Postby Jason » Wed Dec 15, 2010 7:09 am

Thanks again. I went to school at the marine intact. In st. John's been working on the ships spencer 2000 . I,ve been going to write the exam in the last couple years but l've been putting it off
Just wondering about some of the regulations for the steering. Gear and bulges so that I don't miss anything. Thanks again. All the best.

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JollyJack
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Re: two questions that i'm having trouble with for the 2nd class

Postby JollyJack » Wed Dec 15, 2010 7:13 am

I wouldn't worry too much about Regulations in the written exams for 2nd Class. Might come up in Orals though.
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Big Pete
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Re: two questions that i'm having trouble with for the 2nd class

Postby Big Pete » Thu Dec 16, 2010 1:19 am

The important regs are the safety ones.

Remember that it should always be possible to operate the steering gear in two completely independant ways.
Main ones are:-
Steam tiller & relieving gear,
2 seperate direct drive electric motors one powered from emergency switchboard & one from the main switchboard,
2 electro hydraulic pumps, (one powered from emergency switchboard & one from the main switchboard) seperate header/expansion tanks for each pump, 2 seperate pipework systems that can be isolated by shut off valves in an emergency, at least two hydraulic rams, rotary vanes or chambers depending on the steering gear design.
2 independant electric motors to turn an Azipod, each with 2 power supplies, again from main & emergency switchboards.

The Electric Motors are fitted with Thermal overloads that operate audible and visual alarms on the Bridge. THIS IS UNIQUE, ALL OTHER THERMAL OVERLOADS STOP THE MOTOR TO PROTECT IT. In this case it is considered preferable to allow the Bridge watchkeeper to change over to the standby motor manually and then call out the ETO/ Duty Engineer to investigate, rather than to lose steering without warning. If the motor burns out so be it.

S.O.L.A.S. Lays down the minimum time from hard over one direction to hard over the other.

No oil drums or large spares should be stowed in the steering flat in case they break loose and break the pipework (This caused the loss of one ship, I forget which).

With Bilge systems main rules are to ensure adequate capacity, prevent pollution and stop damaged compartments flooding intact ones through the bilge lines.
All the valves in the Bilge system should be non return type. There should be isolating valves at the forward (and aft if applicable ) Engine Room Bulkheads and the collision bulkheads. Bilge pipe work should not run through oil tanks or double bottoms, or close to the ship's sides (Liable to be damaged in collission or grounding). In passenger ships there should be a bilge pump in every watertight compartment. There should be several pumps that can be used on the main Bilge system, usually through cross connections to the Fire / General Service / Ballast sytems and pumps. All suctions should be fitted with strum boxes. In addition there is usually a direct Bilge suction from the Bilge pump.

In addition there should be an Emergency Bilge Injection valve on the main sea water cooling pump.

There will also be an oily water seperator system, often with completely independant pipework, bilge suctions etc.

Spaces outside the Machinery Rooms i.e. F'o'c'sle, cofferdams, void spaces, steering flat, chain lockers etc may be fitted with bilge eductors operated from the fire main, to pump out oil free water.

If you go to the British MCA website you can download guidance notes for surveyors that can be searched for Topics that you are interested in, and they give a good oversight of the rules.

Good luck.

BP
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JK
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Re: two questions that i'm having trouble with for the 2nd class

Postby JK » Thu Dec 16, 2010 1:52 am

The biggest asset to writing fairly convoluted questions like the steering gear one is to be organized in your thoughts and answer. Start at the bridge and work aft. How does the wheel work (and I don't mean turning), how does the system balance, how do you add oil to the system, then down to the telemotor in the SG. How does it work, how does it recenter to stop movement of the quadrant, then the steering pp, how does it pump, how does it center to stop pumping, how does it reverse the flow, then the rams.How do you add oil to the main system? Throw in some construction details of the rapson slide and the carrier bearing.
Drawings are simple, a line sketch of the bridge arrangement, the telemotor and the pump.
Don't forget the safeties and the mechanical stops on the rams. Bonus points if you mention how to set the mechanical stops.

There is a lot of info in this question, so you want to know this down pat. You either know it and do it, or don't know it and discard it. If you are sketchy on enough details, leave it for the last question you attempt. Actually leave it for the last. You don't want to suck up all of your time getting too deep into detail. If the Examiner wants more detail he will ask in the orals.

The same thing applies for the bilge system. This question is very simple. If you know the rules, you can draw it and describe it. Getting this on the 2nds is like a bonus.

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Re: two questions that i'm having trouble with for the 2nd class

Postby Jason » Fri Dec 17, 2010 6:07 pm

Thank you guys so much for the detailed info.I was going through it tonight and I came accross a problem I was wondering if any one can help me with. Ihave a really good drawing of a steering system it its with a control unit and control block my questions are

1 Modern 4 ram steering systems is there another way to change direction of the pump flow with out the use of a control lever

2 Are hunting gears still used on all modern steering gears

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Big Pete
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Re: two questions that i'm having trouble with for the 2nd class

Postby Big Pete » Sat Dec 18, 2010 1:32 pm

Older electro hydraulic steering gears tened to use Helie Shaw / tilting swashplate pumps. These pumps could vary the the output of the pump from 100% in one direction, through zero to 100% in the other direction.
More modern pumps deliver a fixed flow of oil to a solenoid valve. With power off the solenoid valve the oil recirculates through the pump. When either the Port or Starboard solenoid coils are energised oil is delivered from the valve, moving the steering gear in that direction until the signal from a feedback potentiometer on the rudder equals the value of the desired value signal for rudder angle. The solenoid is then de-energised the spool of the solenoid valve is spring loaded back to the neutral position and the steering gear is hydraulically locked in position, untill either the rudder moves or the desired value changes.
Feedback for the control system is entirely electrical now adays, no more hunting gear or mechanical links, no more hydraulic servos, only electrical cable from the hand steering and autopilot to the solenoid valves and feedback potentiometers.

BP.
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Jason
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Re: two questions that i'm having trouble with for the 2nd class

Postby Jason » Sat Dec 18, 2010 4:45 pm

Tanks alote for your time you've been a great help.

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JollyJack
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Re: two questions that i'm having trouble with for the 2nd class

Postby JollyJack » Mon Dec 20, 2010 4:36 am

Jason, if you haven't seen it, if you haven't worked on it or only read about it in a book, DO NOT attempt to answer the question. Answer the questions about things you actually know about, things you have actually done. If you fumble your way through something trying to look clever, your ass will be roasted in Orals and you could fail.

Example, "Sketch and describe an ignition system for a gasoline engine." I answered that one on the K.I.S.S. principle and sketched a simple one cylinder motorcycle engine, with battery, contact breaker points, condenser, cam, coil and spark plug. Wasn't even mentioned on Orals. If I had mentioned electronic ignition, I'd be open to questions about how it works. Why would I even think about a distributer or a multi-cylinder engine? That question, btw, is still out there.

K.I.S.S. is "Keep It Simple, Stupid!" and RTFQ, the other piece of advice, is "Read The F*&^$*@ Question"
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Re: two questions that i'm having trouble with for the 2nd class

Postby D Winsor » Wed Dec 22, 2010 4:24 am

I've read though the responses and there is one thing you shouldn't forget when it comes to the Bilge System that is the "Bilge Ejection Valve" That is is your "Last Line of Defense" against flooding in the Engine Spaces.
The bilge ejection system is a critical part of a ship's bilge system is scrutinized by class societies and port state regulators
Troubleshooting 101 "Don't over think it - K.I.S.S. it"


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