How To Buy Second Hand Boat Engine?

 

It is not possible for everyone to buy a luxury boat or have time to go cruising on a luxury liner. Yet you can consider having your own simple boat which you can use for fishing or enjoying. But you certainly need to buy a diesel engine for that.

Introduction

If you are planning to buy a used marine diesel engine, this article would be really helpful and I will give you some really practical and useful tips to buy them. But before that I would like to suggest that there is no substitute for knowledge. I mean I could tell you a dozen points and you can simply check them and make a perfect deal. Yet it would be better if you know some of the theory behind these engines. If you would like to do so, I would suggest you go through these articles listed in the paragraph below.
There are lot of informative articles on this site about marine diesel engines and we have talked about their theoretical cycles and various components such as the crankshaft, bedplate, pistons, cylinder liner and cylinder head. One important point to be noted here is that these articles considered the mainstream marine diesel engines which are used in large commercial merchant marine vessels or ships. Yet the basic principles behind the engine theory remain the same more or less and even if you are interested in buying a relatively small marine diesel engine for your personal boat, lifeboat, Formula 1 boat, motorized kayak or yatch, which you might want to use for leisure fishing or relaxing, these articles would help increase your knowledge. If you think you have all the background knowledge then you can straight away proceed to the next section and learn the tips

Going Shopping

There are basically 3 ways to go about while buying a marine diesel engine.

1. Buy a New Engine
2. Buy an RTO
3. Rebuild the Engine

The first way is quite obvious; you shop around for the best available engine in terms of your power requirements, size, performance and so forth and buy a brand new engine directly from the manufacturer or from their authorized dealers. All goes well in this scheme except that more often than not, you may find yourself a bit short of cash as new marine diesel engines cost a lot and it is a lot different from going to the corner shop to buy a loaf of bread. There are several popular manufacturers which you could consider buying such as MAN, Caterpillar, Yanmar, Detroit and so forth. But we wont consider this option and will delve straight into the other options namely RTO and Rebuild.

RTO vs Rebuild

RTO

RTO refers to Running Take Out engine and basically it means the engine which has been taken out (from its original or previous boat) while running (not literally though). This obviously ensures that there no serious defects in the engine though you still would have to assess its condition either yourself or get the help of a professional. This is necessary to ensure that the engine is not at the edge (not of technology but its lifespan). Using an RTO can save you substantial sum of money and if you take proper care of your RTO engine you can certainly make it last a long time.

• Do not depend totally on what the salesman says but do check out for the running condition yourself.
• Make sure there are not abnormal noises/vibrations when the engine is running or if there are any leaks of oil, gas or fuel
• Check out the speed control and governor functioning
• Since used engines do not have a fixed MRP like new company engines, try to bargain reasonably and if the seller feels that you know your stuff, you would be in a better position to bargain

Rebuild Engines

The only difference between a rebuild engine and a new engine is that most of the parts are replaced with brand new parts except the basic block of the engine. So they are almost as good as new engines with a much lower cost but they should have been rebuilt by a thorough professional and not a hobbyist, I mean unless you find it adventurous to get stuck in the middle of the sea when your engine fails you at that critical time.

Using Technology

Reading the above information may be quite useful but there is one problem. A loaf of bread is available at literally every corner shop but unfortunately the same cannot be said about second hand marine diesel engines. So why not use the modern day technology of Internet and use websites for searching for such engines.

This would give you a lot of options in terms of make, model, condition and price. You can correspond with them and find out if they can ship the required model to your place. Even if not such an online research would give you a deep insight into the price levels etc which will help you to make a buying decision.
Also though size does matter and normally bigger is considered better, it could also be true the other way round since large websites might have too many options which means you might get confused and lost. So sometimes it is better to contact smaller websites which might have the time to provide personal and customized service to you.
Some of the sites which could be of help are as follows and it depends on what sort, type, model, size and power engine you are looking for.

Marine Compressors: Operation, Maintenance, and Troubleshooting

 

This article discusses the different types of compressors used on board, the uses of compressed air on board, unloading of compressors, safety features of compressors, operating procedure of compressor, routine maintenance of reciprocating compressor, valves overhaul procedure, trouble shooting, etc

DIFFERENT TYPES OF COMPRESSORS USED ON BOARD

Compressors are used for compression of gases by decreasing the volume and imparting a corresponding increase in pressure. There are a different types of compressors used for different uses onboard. We have refrigeration compressors used in air conditioning and refrigeration. We have air compressors for supplying compressed air; we have compressors on the engine turbochargers supplying compressed air to the engines for combustion. There are different types of compressors like centrifugal compressors, rotary vanes compressors, rotary screw compressor, reciprocating air compressors, etc. In this article we shall be discussing the reciprocating air compressors.
Onboard we have different types of air compressors in use. There are main air compressors used for supplying high pressure air for starting of the main engine and auxiliary engines, control air compressor for supplying control air, topping air compressors for topping up and taking account of the leakages, and on some ships we have deck air compressors to give air for the use on decks. In addition we have a special oil free compressor for filling up the breathing air bottles known as the breathing air compressors.
Generally two pressures of air are used: 30 bars high pressure air used generally for starting of the engines and 7 bars low pressure air used for control and general service air. In the choice of an air compressors for applications requiring air above 7 bars, we generally use reciprocating air compressors as it has a more positive sealing in comparison to the other types of compressors like rotary vane, centrifugal, rotary screw etc. In reciprocating compressors the compression ratio of 1:7 is the limit due to the rise in temperature, thus to get 35 bars pressure the machine has to be a double stage compressor with intercooling. Most of the marine compressors used are two staged reciprocating compressors with intercooling and after cooling.

Marine Reciprocating Engine

USES OF COMPRESSED AIR ONBOARD MERCHANT SHIPS

* On merchant ships compressed air is used for a variety of uses some of which have been mentioned below:
* For automation and control of main engines, auxiliary engines, etc.
* For starting of the main engines, auxiliary engines, emergency generators, emergency fire pumps, etc.
* For heaving the life boat up by the use of an air motor.
* For pressurizing the hydrophores for domestic fresh water and sanitary water used in accommodation.
* For use in the sewage plant for conducting aerobic sewage breakdowns.
* For use in fog horns and ships whistles.
* For use in pneumatic tools like pneumatic grinder, pneumatic chisels, pneumatic drills, pneumatic spanners, etc.
* For use in painting operations.
* For general cleaning.
* For soot blowing of the boilers.
* Used in pneumatic pumps for oil transfer.
* And used as general service air

UNLOADING OF THE COMPRESSORS

All compressors need to be unloaded during starting, stopping, and at regular intervals. It is for the following reasons:
1. During the starting of a motor the starting current is very high, so to avoid further overloading of the motor the compressor is started unloaded. When the current comes down to the running value, the unloader is closed and the compressor comes on load.
2. As the air is compressed in volume it releases a large amount of moisture. This oily water mixture is incompressible and if it is present inside the compression chamber it can damage the piston and the valves. For this reason also the compressor is started unloaded so that all the moisture present inside is drained.
3. At stopping the same is done so as to drain all the moisture inside and in preparation for the next starting.
4. Intermittently the compressor is unloaded to remove the condensed water inside which could go outside with the air.
For the purpose of unloading there are different types of unloaders some of them are pneumatic and some are solenoid operated. They all have a timer in the circuit which energizes the solenoid at the starting, stopping, and intermittently.

SAFETY FEATURES OF MARINE COMPRESSORS

Marine compressors have various safety features and cutouts installed so that they will trip when running in an unsafe mode. The compressors are reliable machines, but have to be maintained properly and in the proper intervals. There have been cases of the cylinder heads bursting and often resulting in fatalities. The various safety devices put in a marine compressor are as follows:
1. Lubricating oil low pressure trip
2. Cooling water high temperature trip
3. Motor overload trip and Motor overheating trip

OPERATING PROCEDURE OF A RECIPROCATING COMPRESSOR

The operating manual of the particular machine would give the specific items to be checked and the same must be read by the marine engineer upon joining the ship. However a rough guideline has been presented below:
1. Lubrication: check the oil level in the sump and in the lubricator tank.
2. Unloading: the valves in the unloading lines must be open.
3. Pressure gauge cocks: the cocks must be slightly open to avoid excessive pressure fluctuations which can damage the pressure gauges.
4. Air filter: check that the air intake filter is clean.
5. Cooling: check that the cooling water pressure is correct and in the case of attached pumps a visual check of the pump and all the valves in the line must be open.
6. Relief valves: some relief valves have hand testing levers given for testing, the same can be done.
7. Air line piping: check that all the valves in the discharge piping are open and correctly lined up.
8. Final check: the compressor can be turned a few revolutions with a turning bar to check for the free movement.
After the above checks have been made a compressor may be started with the unloaders open.

ROUTINE MAINTENANCE OF RECIPROCATING COMPRESSORS

Though the maintenance done on the compressors onboard would depend on the manufacturers advice and the planned maintenance program set up by the company, the below is a rough guideline about what is to be done for a new joining marine engineer.
1. Clean air filter at 250 running hours. Though neglected and often thought as ordinary, this filter is in fact very important as it is filtering the contaminants from coming inside the compression space and reducing abrasions on the liner surface. Also a dirty air inlet filter can raise the delivery temperature of the air to a dangerous level which can be well above the lubricating oil flash point and near the auto ignition point. Thus a badly maintained air inlet filter can cause an explosion.
2. Clean and inspect valves at 250 running hours. The valve is the heart of the compressor, and it operates once every revolution. The valves can be damaged due to impact forces or due to the ingress of foreign particles. Excessive lubrication also has been known to damage the valves. The valves should be removed, inspected, and overhauled at regular intervals. A broken valve can fall onto the piston and cause extensive damages, thus for this reason the valve maintenance is of vital importance.
3. Change crankcase oil at 500 running hours. Lubricating oil can lose its property over a period of time due to the onerous operating conditions. However the synthetic lubricating oils can be used for a longer period.
4. Check drive belts at 250 running hours. A v-belt is generally used to drive the cooling water pump. The tightness of the belt should be checked and adjusted to the correct value at proper intervals. In addition a belt dressing spray would protect the belts as well as increase the transmission of the power and reduce the slippage.
5. Check unloader operation at 250 running hours. At a regular interval the operation of the unloaders should be checked and if not satisfactory should be investigated and corrected.
The above is an example of the routine maintenance of the air compressors. In addition to the above at routine intervals the piston would have to be pulled out and the piston rings changed, bumping clearances checked, bearings changed. All this would be done on the basis of the planned maintenance program based on the manufacturer’s advice.

VALVES OVERHAUL PROCEDURE

The compressor must first be electrically isolated with the fuses removed and an electrical isolation and work permit granted by the chief engineer. Thereafter the first stage and the second stage suction and discharge valves should be removed and brought to the workshop for overhauling.
Marine compressors use the HOERBIGER automatic valves. The suction and the discharge valves look similar; however the direction of the operation and the spring stiffness differs. The suction valve springs are of lower spring stiffness than the discharge ones and they must never be mixed up. Also when using new spare parts the part number must be carefully checked from the operation and maintenance manual to avoid mixing them up.
When opened up the suction valves are found to be in clean condition while the discharge valves would have some degree of carbonization. In case a valve is opened up and some parts are found to be broken, all the broken parts must be located to avoid any further damage to the machine. An exploded view of the compressor valve has been shown and the overhaul procedure is as follows:
1. Remove the split pin and open the castle nut.
2. Dismantle all the parts and soak in kerosene or clean diesel oil.
3. Clean all the parts with a soft brush. In case of a hard deposit a copper plate of washer can be used for the scraping action.
4. Check the valve plates and the valve seats for any damage and cracks. If any signs of fatigue cracks on the valve plates are present, then the valve plate must be replaced with new ones. The valve plate must never be turned over and used as it can lead to fatigue failure.
5. The valve plate and the valve seat must be separately lapped on a surface plate using fine and extra fine grinding paste.
6. Thereafter all the parts must be washed with diesel and cleaned with compressed air.
7. The valve should then be assembled, with the lapped surface of the valve plate and the valve seat facing each other.
8. After the assembly of the valve the operation of the valve should be checked by a soft wooden stick.
After the overhaul the valves have to be checked for leakage. The space above the valve plate should be filled up with water or light oil like kerosene. If after a few minutes no drop in level or leakage is there then the valve is satisfactory for the use. While installing care should be taken to avoid the interchange of the suction and the discharge valves, as it could lead to an explosion due to over pressurization of the compression chamber.

Compressor Automatic Valve

TROUBLESHOOTING MARINE COMPRESSORS

Though the problems encountered onboard differ from ship to ship, a brief guideline is given regarding the causes of the different symptoms.
1. Lube oil pressure low: causes can be leakage in pipes, suction strainer choked, oil grade wrong, gear pump faulty, faulty pressure gauge, increased clearances of the bearings, and oil level low.
2. Cooling water high temperature: causes can be cooling water valves closed, cooling water piping blocked, cooling water pump belt lose or broken, cooling water pump faulty, no flow of cooling water, and low level of cooling water in the expansion tank.
3. Compressor noisy: causes can be bearings worn, crankshaft end play high, discharge pressure high, poor foundation, small bumping clearance, piston rings worn, liner worn out causing piston slap, valves not properly seated, and valves broken or faulty.
4. First stage discharge pressure low: causes can be that the first stage suction valve is not closing fully and allowing the air to leak during the compression or it is not opening fully allowing less air to come in the chamber or the discharge valve is faulty and opening prematurely or incorrect springs have been fitted which are compressing on little pressure, intake filter fouled, leakage from piston rings.
5. First stage discharge pressure high: causes can be that the second stage suction valve is not holding and while compression high pressure air is coming to the intercooler and showing an increase in the pressure, intercooler tubes choked.
6. Second stage discharge pressure low: causes can be leakage from the piston rings, second stage suction valve faulty and allowing the air to escape, second stage discharge valve leaking or opening prematurely due to wrong springs fitted.
7. Second stage discharge pressure high: causes can be obstruction in the after cooler, obstruction in the discharge valve, air bottle pressure high, second stage discharge valve springs very stiff.
The above is just a brief exposure to the problems encountered onboard and how it must be investigated. An experienced marine engineer keeps an eye on the parameters and knows when maintenance is expected.

CONCLUSION

A compressed air system used onboard is very important to the marine engineer and without any air the ship would soon become a dead ship. The various parts of the compressed air system, be it the compressors, the pipe lines, or the air bottles have to be maintained in good condition. In this article a brief guideline has been given about the compressors used onboard, use of compressed air onboard, the safety devices fitted, the importance of unloading during starting, the operating procedure, the basic maintenance, the valves overhaul procedure and the trouble shooting have all been discussed.
                      It is hoped it would guide junior engineers about the various facets of marine compressors.

How such a huge ship is able to move

Do you wonder how such a huge ship is able to move. Let us discuss the phenomenon behind ship movement

Introduction

A modern day ship consists of all the luxuries which can be imagined in a top rated hotel, but still the basics of propulsion remain the same, as perhaps they were when human beings started to cross the first small stream of water perhaps in a skin boat or a coracle. Of course a lot has changed since then and nowadays modern ships do not use ores or manual means for propulsion, but depend on huge machineries for this purpose.
We all wonder how such a huge ship is able to move forward. There are different forms of propulsion. Some are by taking power directly from the engine or by means of electrical means or by means of steam turbines. Some ship can even be driven by a nuclear energy powered engine. We will learn about various types of propulsion systems used in other articles on this site.
For the time being let us focus on the topic under discussion and take a look at the forward ship movements....

How a ship moves ahead?

• We all know that a ship is moving with the help of a propulsion device. The propulsion device may be a fixed pitch propeller, controllable pitch propeller, azimuth propeller, shrouded propeller, or a voith schneider propeller. Now lets consider the case of a simple propeller of fixed pitch.
• Main engine or whatever may be the propulsor, when it rotates it imparts momentum to the medium (ie) to the water.
• When a propeller is rotating, it produces thrust on water. Now the thrust from propeller is transferred to the water. Since the amount of water is enormous according to Newtons Third Law, the thrust comes back to the ship and this thrust moves the ship in ahead (or astern) direction.
• This thrust is acting on the ship.

Why do we need astern movement?
It may seem a bit strange that one asks why an astern movement is required on any means of land transport, but yes this question certainly has a relevance in context of shipping (as well as aviation). A ship normally would not move in the astern direction but here are a few situations wherein the navigation officers might be required to move the ship in astern direction and these situations can be either of the following

• Astern movement is given to stop the ship soon. Even when the engine is stopped, due to the momentum, the ship will further move to some extent.
• At this situation when you give astern movement, this momentum will be stopped as the propeller starts to rotate in other-way-round.
• This is achieved by means of reversing the engine. There are different methods of reversing. They may be achieved by axial shifting of the cam shaft or by using servomotors or by shifting the cam follower rollers.

Top 13 Things a Junior Engineer Should Do As Soon As Possible When New to a Ship

A Junior Engineer when new to ship is surrounded by doubts, confusion, and fear. When new to ship, it is very normal for any marine engineering professional to make mistakes. For this reason, senior engineers in the engine room keep themselves a bit lenient and give the fresher space and time to absorb and learn things. However, a junior engineer shouldn’t expect unlimited time to learn and grasp things. After the very first month, or probably after 15 days, the new engineer would be expected to carry out his or her duties independently without making mistakes.

It is therefore important that a junior engineer, though officially on a training period should know and learn as fast he or she can. The faster the engineer grasps and learns things; the better would be the future learning process. In this article we bring you the top 13 things that a Junior engineer should do when new to a ship.
Top 13 Things a Junior Engineer Should Do As Soon As Possible When New to a Ship
1. Ship Familiarisation
Familiarise yourself with the ship as soon as possible. Don’t have a mindset that you are going to be there on the ship for several months and thus have ample of time to do so later. The sooner you familiarize with the ship, the better and easier it would be for you.
2. Know the Escape Routes Thoroughly
While familiarizing yourself with the ship, make sure you remember ship’s emergency escape routes and doors like the back of your hand. This is the first lesson of safety on ship, especially for new crew members.
3. Know the location of Muster Stations
Find and remember the way and location of muster stations. You don’t want yourself you get lost during an emergency or a drill.

4. Should know who the DPA is
Junior engineer should find out who the designated person ashore (DPA) of the ship is. This is important according to the International Safety Management Code (ISM).
5. Segregation of garbage
Junior Engineer should know what garbage to throw in which designated coloured garbage box. This would be the same for all the ships and thus would be helpful for him throughout his sailing life.

6. Company rules and policies
In order to save himself and the ship from any trouble, the junior engineer should know the company rules and policies thoroughly. This would give him a clear idea as to what he can do and what he cannot when on ship.
7. How to Use Emergency Equipments
Personal safety comes first for any crew member new to the ship. Junior engineer should learn how to use emergency equipments such as emergency generator, life saving appliances, fire fighting appliances etc. along with their locations.

8. Learn About Various Alarms
Learn about identifying various alarms such as Co2 alarm, general alarm, engine room alarm, and fire alarm, along with actions to take in case of such situations.

9. Launching of Life Boat
It is imperative that everyone on ship knows how to launch a life boat. A junior engineer should know how to launch and operate a life boat, along with the procedure to start the life boat’s engine.

10. Know SOPEP
Know about the sopep locker and what all things are present in it.

11. Know the Automation in the Control Room
Know how to operate the basic operations and equipments in the engine room’s control room.

12. Learn About Manuals
Find out what all manuals are available in the engine room and where are they located.
13. Familiarize with Engine Room and Engine Room Workshop
This is where you would be spending most of your time on ship. Know each and every corner of these places.