1-433 Bulk carriers (or bulkers as they are often called) have had a sad history in recent years with one being lost on average every month. They are also perhaps the most hazardous vessel for a marine surveyor to encounter. They have been designed to minimise their registered tonnage measurements and usually have no raised forecastle. The loss of the Derbyshire highlighted the problem to the world at large. This was because it was a British ship with British crew and the UK press seized onto the human loss element. This is fair enough, and yet the world has generally ignored the other 300 or so losses of these vessels.
The scantlings of these vessels has also been set to a minimum, the lighter the hull the more cargo you can carry. In the hands of uncaring owners and poorly paid crews, these workhorses in the industry soon deteriorate and become a risk to themselves and those that board them.
1-434 The various bulk cargoes these ships carry also create problems for the ships which carry them, and damage is often caused by corrosion and damage caused by unsuitable loading. Too often this damage went unnoticed, having been undetected due to inadequate surveying standards. In short the losses have arisen where commercial rather than safety interests have been the overriding factor.
1-435 IMO and IACS have been very hard at work in improving bulk carrier safety, with improved design and increased structural requirements. There has been a great deal of debate about compulsory double hulls for bulkers, but at present this remains optional.
Figure 8
In the UK Both the MCA and the HSE are Calling for More Attention to be Paid to Lashing on Container Ships. The Lack of Suitable Access to Lashing Work
Stations is a Common Cause of Accidents to Stevedores as it Causes Unorthodox and Unsafe Practices. Marine Surveyors who have the Important Task of Seeing that Containers have been Properly Lashed should be Aware of
this Hazard. Picture Feb 2004
Module 1 Types of Survey – Cargo-related Surveys
1-436 IMO also has produced the BLU Code which is the Code of Practice for the Safe Loading and Unloading of Bulk Carriers and should be complied with by both ship and terminal operators. (This is an essential document for those regularly involved in the trade. Others would be wise to make themselves familiar with its existence. Refer to the Appendix 5 to this module for a list of its contents.)
1-437 Marine Surveyors with experience also as ships’ officers on bulk ships can be very effective in ensuring that the essential co-operation between the ship and the port personnel will ensure the utmost care and attention concerning the planning of the loading and discharging operation. This will require suitable distribution of weights in each hold and the speed of the loading operation.
Always be aware that often the terminal operators are more concerned with getting the ship off the berth than with the ship’s overall safety.
1-438 A prime consideration must be the loading/discharging plan. It needs to cover:
(a) Distribution of cargo within the holds (taking into account its suitability at boththe loading and discharging port/s).
(b) Speed of loading/discharging of each hold.
(c) The ship’s capability of ballasting/deballasting (considered in association with above).
1-439 Attention must be paid to the requirements of any ballast or de-ballasting operation. The same problems apply to ballasting and deballasting as mentioned in 1-348 above concerning the rate of loading/discharging and to distribution of cargo. Both operations can materially affect the vessel’s structure by imposing severe stresses, causing significant damage. In giving proper consideration to these matters the terminal administration should sign and accept the IMO approved ship/shore checklist and provide the ship with instructions, in the appropriate language, regarding its conduct at the terminal.
1-440 Another area of concern is that of damage done to the ship during cargo operations by handling equipment. This damage is specially serious when caused to hatches and hatch coamings but it also applies to fittings in the hold.
Ships’ officers, and the surveyor too, are generally required to monitor this and liaise with the terminal operators to minimise any damage caused by grabs and machinery, principally bulldozers, operated within the hold. Provision of a GA hatch plan, showing the location of hold ladders, pipes and other fittings prior to commencing will facilitate this. Marine surveyors should also consider the cleanliness and fitness to receive the cargo, and the taking of samples during loading or prior to discharge.
1-441 The most common types of bulk cargoes are grain, iron ore, coal, sugar, scrap steel, chemicals and fertilisers. They are conveyed across the oceans in vast quantities and generally do not present major problems for their receivers but many are susceptible to contamination from the residue of previously carried cargoes, rust from the ship’s structure, moisture from sweat, rain during loading, sea water ingress through leaking hatches and fresh/salt water from leaking pipes.
1-442 Be particularly concerned with coal and some chemicals that require careful temperature monitoring as they are susceptible to heating damage and in some
Types of Survey – Cargo-related Surveys Module 1
cases to spontaneous combustion. The IMO Code of Safe Practice for Solid Bulk Cargoes provides information on the stowage and carriage of most common, and many uncommon, bulk cargoes.
1-443 With bulk cargoes the quantity out-turned, sometimes with unexplained shortages exceeding an acceptable percentage, can present difficulty in determining where the losses occurred and will result in substantial claims for these losses. On some occasions they may be no more than paper losses and, where surveyors are not involved until after the discharge, it is often very difficult to detect where the losses have really occurred.
1-444 Sampling usually plays a large part in the role of the surveyor during the loading and discharging of bulk cargoes and is commonly required to determine the quality, moisture content, and possibly temperature of the cargo to be loaded or on board. But it is not always as simple and straightforward as it may appear as samples are usually required to be representative samples of the whole. They may also sometimes need to be more specific of those at any place or time during a cargo operation, particularly if a problem is met at any stage.
1-445 Grain cargoes have, for many years, engaged surveyors’ attention in the grain loading ports of the world.The regulations imposed by the SOLAS convention on the carriage of grain are extensive although recent years have seen some simplification. This has been assisted by the design of modern bulk carriers and it is the more conventional cargo ship that presents the most problems. As a consequence they are rarely “fixed”
for grain cargoes as bulkers are generally readily available.
Figure 9
The 2,100 gt General Cargo Vessel Scotia Being Loaded with Grain at UK the Port of Dover. The Scotia is Owned by Baum and Company and was Built in
1987. Photographed in October 2002
Module 1 Types of Survey – Cargo-related Surveys
1-446 Loading will have to comply with the requirements of the International Grain Code (except where exemptions have been granted, in which case the stability report should say so) and charterparties will usually also have some specific requirements relating to the loading of a grain cargo. Surveyor’s instructions should include reference to them. In many cases there will be a requirement for, and a restriction to, the involvement of certain specific approved surveyors. Although private sur-veyors may attend to much of the planning and overseeing of a grain loading there will usually be a requirement for a government surveyor to approve the overall plan.
12.6.1 Draught Surveys
1-447 Draught marks are permanently indicated on the ships’ side, both forward and aft. Conducting draught surveys is one popular method used to determine the quantity of cargo loaded or discharged particularly in the case of bulk cargoes such as that carried by the vessel pictured below. They are convenient and reasonably reliable and are carried out by comparing the vessel’s draught before and after the loading or discharging operation.
1-448 By taking the draught of a vessel the marine surveyor can measure the displacement of the ship at the start and completion of the cargo operation. The difference between the two measurements will represent the weight of cargo added or removed. Of course other allowances will have to be made if the vessel has loaded fuel oil, water, or other items. Simple as all this may seem it is actually quite a complicated and often difficult process as so many factors can affect the accuracy of the two comparative draught readings obtained. There are other difficulties to overcome.
Figure 10
A Typical Panamax Bulk Carrier, the Desert Eagle, Owned by Atlantic Bulk Carriers Built in 2002 in South Korea and Registered in Greece, the
Vessel is 74,630 dwt.
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1-449 The accuracy of draught surveys increases with the quantity of cargo being carried by the vessel. Up to about 5,000 tonnes actual weighing of the cargo will probably be more accurate but, as the quantity increases so does the accuracy of the draught survey. At about 10,000 tonnes, and with good conditions for taking the measurements, accuracy can be of the order of between 1% and 2%.
Even for the smaller quantities draught surveys may provide a useful check upon other methods. The following points are mentioned to give some indication of the requirements in carrying out draught surveys but they touch only very lightly on the subject. Draught surveys should not be embarked upon by novice surveyors without some first hand guidance from experienced surveyors.
1-450 The surveyor has first to observe the draught readings at which the ship is floating and these have to be reasonably accurate. They can be complicated by many basic factors including:
(a) The clarity of the paint on the draught marks.
(b) The adequacy of the light falling on them.
(c) The surveyor’s proximity to the marks (hanging from a rope ladder from the overhang of the offside quarter in a strong wind can be exciting but not very productive! Sighting from a boat is usually the best method).
(d) The disturbance at the water level (by wind and swell).
(e) When in a strong current, whether the ship is “squatting” and/or has a build up of water at its stem or stern.
(f) Whether the ship, as a longitudinal girder, is deformed due to its condition of loading, or due to ambient temperature.
1-451 The effect of weather disturbance on draught readings can be reduced by means of a draught tube used adjacent to the draught marks. It “stills” the water beside the mark at which the draught is read. Distant reading draught gauges are not accurate enough for this purpose. Another form of assistance can be provided by means of a special clinometer which allows the surveyor to correct for a vessel’s list when the weather permits only an accurate reading of the draught on the lee side.
1-452 These listed items often cover only the first difficulties encountered and once an accurate draught reading has been obtained it may need correcting for the fact that draught marks are often not on the fore or aft perpendiculars. It is then necessary to obtain an accurate density of the water in which the ship is floating.
The sea water density can be affected by a number of variables such as:
(a) Depth at which they are taken (salinity and temperature variables).
(b) Location, relative to the fore and aft line of the ship (density can vary between the stem and the stern for the same reasons).
(c) Local distortions caused by ship’s or shore discharges.
Module 1 Types of Survey – Cargo-related Surveys
1-453 Once a representative sample has been achieved the density has to be obtained by means of a hydrometer, and for accuracy a special draught survey instrument should be used. Temperature plays a part as a hydrometer reads correctly at only one specified temperature and the reading obtained will be slightly in error at other temperatures due to expansion and contraction of the material of which it is constructed.
1-454 Having fine tuned the draught readings, the surveyor then has to determine the changes in quantities of ballast and fresh water, fuel and diesel oil, stores, spares and other variables on board. This requires sounding, or at least witnessing, ship’s officers’ taking of soundings, of all the double bottom, deep and wing tanks (even empty tanks too) on the vessel. List and trim can affect the accuracy of tank quantity calculations due to air entrapment when pressed up.
Ideally they should be sounded when sufficiently full to give a good sounding, but when no air can be trapped in pockets.
1-455 Reliance has to be placed on the figures given by the builders for tank capacities and all the other hydrostatic information provided. These are usually reasonably accurate but are occasionally unreliable and an error of about one tonne per 1,000 tonnes can be introduced because they sometimes assume fresh water density as being 1.0000 at 15C; a slight inaccuracy.
1-456 Finally, and often with some haste with the master, pilot and terminal operator breathing down the surveyor’s neck as the ship is about to sail, the surveyor is required to complete the calculations and confirm the quantity of cargo loaded or discharged.
1-457 A marine surveyor taking proper care, can expect to obtain reasonably accurate results from a draught survey. It is accepted in most dry bulk trades that an accuracy of about 0.5% is reasonable and feasible provided the quantity is large enough. Much depends upon the co-operation received from the ship’s personnel and whether they want the surveyor to arrive at an accurate figure or not. Sometimes owners and charterers will deliberately hinder accurate readings so as to obtain a figure more favourable to their position, and surveyors need to be fully alive to this possibility.
1-458 Of course draught surveys will not account for cargo lost through spillage when grabs are handling the commodity into and out of the vessel. Another consideration has to be given to water inclusion through rain or condensation, and for this sampling is likely to be required. It does not however normally constitutes part of the actual draught survey. A comparison should be made between the figures obtained from the draught/ ullage surveys and weightometer figures, although the surveyor’s figures are the principal ones used.
SELF-ASSESSMENT QUESTION
To what particular considerations would you pay heed when carrying out a draught survey for the loading of a 20,000 ton bulk carrier?
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