With China’s increasing demand for soya beans and the Sino-American trade conflict in recent years, Brazil, Argentina and Uruguay have come to contribute greater shares of soya bean imports. However, claims for cargo damage have been commonplace due to high moisture content of the beans which are often harvested in the warm and humid climate, plus the rather long voyages from South America to China. The receivers’ claims against the carrier’s negligence in cargo caring and proper ventilation are often supported by the Chinese maritime court, for in too many cases there is either evidence for the ship’s negligence, or there is not enough evidence for proper ventilation records. It is still a great challenge to have the court recognize that heat damage of soybeans is due to the inherent nature of cargo. Therefore, it is particularly important for carriers to maintain good ventilation records to demonstrate that their obligations have been prudently performed.

I. Heat damage incidents

Case No.1: Ship A loaded soybeans from the port of Montevideo in Uruguay and the port of Blanca in Argentina to Jiangyin, China. The cargo loaded from Montevideo (average MC at 13.4%) was found discolored, caked and damaged by heat during discharge while the cargo loaded from Blanca (MC at 12.7%) remained intact. There was a rain record during loading at the port of Montevideo, and the crew did not measure the cargo hold dew point temperature or take any ventilation measures during the voyage until 10 days prior to arrival to take out the fumigant, which was 16 days late than the time required on the fumigation certificate. The court then decided that the carrier failed its obligation of cargo caring and should be liable for the damage since no evidence could be provided to prove that effective measures were taken to protect the cargo from the rain, or to prove that the cargo was not damaged during loading or during transportation.

Case No.2: Ship B shipped soybeans from Paranagua Port, Brazil to Jiangyin, China. The quality inspection report at the loading port showed a moisture content of 12.23%. Cargo in hold No.4 was found damaged after arrival. During the voyage, fumigation ended on May 15, and all 7 cargo holds were ventilated for 9-12 hours from May 16 to May 23, for 12 hours on June 12, and for 9-12 hours from June 14 to June 19, respectively. Where ventilation was not carried out, justification of “bad weather” was provided in the records onboard for the period between May 24 and May 29, and “not applicable” for the period between May 30 and June 11 as well as for June 13. The court held that the carrier failed to prove that it had fulfilled its obligation to carefully manage the goods as “not applicable” cannot adequately justify the reason not to ventilate.

Case No.3: Ship C shipped soybeans from Rio Grande Port, Brazil to Tianjin, China. The average moisture content of the cargo was 12.1%. The cargo was found discolored, fermented with mould after arrival at the discharging port. The cargo insurer claimed to recover from the carrier after compensating the receiver. The carrier submitted sufficient evidence for proper and careful handling of the cargo, including evidence of seaworthiness and cargoworthiness; photos of the cargo at the loading and discharging port; cargo safety management manual; records for cargo storage and monitoring and cargo inspection reports; cargo hold ventilation and temperature records; bilge and fuel tank temperature records; navigation records in bad weather, and etc. The claim was not supported as the court held that the claimant can’t prove that the alleged damage was caused during the voyage.

II. Reasons for soybeans self-heating

Soya beans are rich in proteins and fat and every bean is covered in dormant mould spores that can begin to grow and subsequently deteriorate a cargo under certain environment conditions. Requirements of moisture content and temperature for safe storage and carriage of soya beans are hence very different. At sufficiently elevated moisture content and temperature, the cargo is microbiologically unstable and prone to mould growth. As respiration accelerates, heat and moisture accumulated in the holds may cause the cargo to increase in temperature and ultimately to deteriorate. Also, excessive heat may produce blackened “bin-burned” beans due to its low thermal stability.

At a temperature of about 25℃, soya beans with a moisture content below 13% are generally regarded as safe for carriage (see table 1 for “Approximate” Allowable Storage Time), but the risk of deterioration increases at moisture contents above this limit. Because of the heterogeneity of soya bean cargoes, moisture content values reported on cargo quality certificates at load ports are usually an average for the entire shipment, which means that portions of a cargo are loaded above the stated contractual value.

Furthermore, the contractual limits for moisture content of South American soya beans (e.g. 14% for Brazil and 13.5% for Argentina) are often above the recommended value for safe storage. In other words, many cargoes may be loaded within contract specifications but still be microbiologically unstable, with therefore a significant risk of self-heating during an about 6-week voyage to China.

In addition to elevated moisture content and cargo temperatures, other factors including age, storage history, presence of foreign matter and pre-shipment conditions can affect the propensity of soya beans to self-heat. Therefore, the rate of cargo spoilage can be accelerated by these additional factors, even when the cargo is loaded at a relatively low moisture content and cargo temperature. Prolonged storage periods prior to loading can drastically reduce the safe storage life of a cargo, allowing moulds/fungi to grow, albeit slowly during the storage period and then to accelerate their growth and proliferation when on board a vessel.

Sales contracts often set forth detailed agreements on the quality of a cargo, and in some cases, a certain level of heat damage, crushing, discolouration and the presence of bean stalks or bean pods can be acceptable. However, these damaged portions of a cargo, emitting heat more intensely in faster respiration than sound cargoes, will further promote the growth of mould.

The very existence of foreign matters will then prevent air flow during storage and transportation of soya beans and create room for the organisms to generate mould.

III. Ventilation on ships

The high moisture content and cargo temperature will facilitate respiration of shipped soybeans, further releasing moisture and heat that usually move upwards and activate microorganisms at the upper layer of the cargo. As a result, moulds accumulate below the surface. At the same time, warm and humid air rise and condense when in contact with cooled steel structure such as hatch covers, forming ship sweat that will drip onto the cargo and promote mould growth on the surface. Where the heat damage is caused by ship sweat, the mould is often in strips along the longitudinal structure of hatch covers, which may be used by receivers as proof of lack of proper ventilation.

Proper natural ventilation can help reduce or prevent damage caused by ship sweat by replacing the moist air in upper cargo hold with dry air from the outside. However, it cannot prevent self-heating and mould growth inside the cargo. Also, it should be noted that ventilation does not prevent the hull from sweating when the cargo is self-heating.

IV. Common misunderstandings

Below are some common misunderstandings among masters and crews in terms of ventilation management, especially when carrying grain cargoes.

1. Ventilation is unnecessary for bulk grain cargoes

Moisture at sea is often around 85% and some believe that ventilation will cause damage to cargoes or ventilation is unnecessary as it will not help prevent self-heating or moulding of the cargo. However, ventilation should be continued so long as Dewpoint and Three Degree Rule indicate it is appropriate or as the charterer/fumigator instructs.

2. Suspension of ventilation at night

It has been common practice for most crew to discontinue ventilation at night as they believe that night-time is associated with the formation of dew and the dew in the air could affect the cargo during the night-time. However, this is a misconception. Ambient temperatures are usually lower at night, and ship sweat is more likely to form during the dark hours, and therefore ventilation should be continued so long as Dewpoint and Three Degree Rule indicate it is appropriate.

Another reason for the crew to stop ventilation at night is that their ability to judge the severity of rainwater or shipping spray in the hours of darkness may be impaired. Furthermore, there may be insufficient crew available to assist with the closure of ventilation in a timely manner. Masters should then carefully assess if the ship’s ventilation system can prevent ingress of rainwater and shipping spray, the availability of personnel and the possibility of sweat damage if ventilation stopped to show ventilation has been managed in a prudent manner.

3. Suspension of ventilation in fog

Crew often simply shut off ventilation during foggy weather. The truth is that the presence of mist or fog has no bearing on the ventilation, and Masters should continue to apply either the Three Degree Rule or the Dewpoint Rule regardless of fog.

4. Suspension of ventilation in rain or when the vessel ships seas or spray

It is usual to suspend ventilation when it is raining or when the vessel ships seas for fear that rainwater will be drawn into the ventilators and the cargo will become wetted. However, it is perfectly possible for it to be raining at a time when either comparison of dewpoints or the Three Degree Rule indicates it is appropriate to ventilate. In such cases, the cargo may be damaged by sweat if not ventilated, and by contrast may be damaged by rainwater ingress if ventilated. Therefore, Masters should be fully familiar with their vessel’s ventilation arrangements and carefully assess the situation that how much water ingress can be expected by those vents (mushroom type is less risky while inlet on vertical side of hatch cover is of high risk). If there is any doubt, it would be prudent to suspend ventilation and record properly in the ventilation log, as it may be difficult to defend in the event of a claim for cargo damage by rain or water ingress.

5. Good weather works for all

Ship’s crew often deem that ventilation can be conducted whenever the weather was good. This is likely to be inappropriate since good weather are often those conditions associated with high temperatures and high moisture content. The fundamental decision taken by the Master to ventilate the cargo space or not should be still based on either the ‘Dewpoint Rule’ or the ‘Three Degree Rule’.

V. Advice to Members

1. The carrier should make sure that the crew is familiar with the requirements for cargo management, especially for fumigation and ventilation.
2. To eliminate/minimize the formation of sweat and the associated risk of cargo damage, the underlying principle is to keep the drewpoint of the air within the hold below the temperature of the hold structure and the cargo to stop the formation of ship and cargo sweat. The fundamental decision to ventilate or not should be based on either the Dewpoint Rule or the Three Degree Rule. The later is preferable for carriage of soybeans as dewpoint may not be accurately determined. Where the Three Degree Rule is applied, ventilation requirements are estimated by comparing the average cargo temperature at the time of loading with the outside air temperature. It is recommended to have an infrared thermometer on the ship to measure cargo temperature while loading and also to monitor the self-heating risk.
3. It is advisable to measure the cargo temperature at regular intervals while applying the Three Degree Rule and inform the shipper/charterer immediately once they find signs of cargo self-heating.
4. Measure outside temperature every four hours to see if ventilation can be carried out in changing weather conditions.
5. It is not unusual to carry out fumigation during the voyage after loading of the soybean cargo. The master should follow the charterer or the fumigator’s instruction when deciding to ventilate. Check cargo conditions upon completion of fumigation and prohibit entrance into the hold without safety check first.
6. If there’s a risk of seawater or rainwater leaking into cargo holds during adverse weather, ventilation should be stopped immediately with all openings closed. The situation should be recorded in detail in the log book and ventilation record.
7. Inspect the cargo holds for signs of sweat condensation regularly if circumstances permit. Ship sweat usually forms underneath the access hatch cover and at inner hatch coamings. The condition of the cargo surface should be visually inspected regularly and the shipper/charter should be notified as soon as possible if there’s any sign of cargo damage.
8. Where cargo damage occurs during the voyage, the master should ventilate as far as possible in accordance with ventilation rules or instructions of the shipper/charterer. If weather and sea conditions permit, open hatch covers for ventilation to reduce ship sweat.
9. Soybean cargoes may be damaged by heated bunker tanks and the cargo would further emit heat and moisture, increasing the risk of sweat. The bunkers used during the voyage should be drawn as far as possible from tanks situated well away from holds containing soybeans. If impracticable, bunker tanks adjoining cargo spaces should be heated only when required, ensuring that the temperature does not rise above operational level.

VI. Ventilation record keeping

During ship operation, there are numerous cases where owners lose their positive position in defending claims for cargo damage allegedly caused by improper or inadequate ventilation due to improper or lack of records. Therefore, while proper ventilation can effectively prevent cargo from sweat damage, proper and sufficient ventilation records are crucial to the interests of shipowners. In particular, in the event of sweat damage to cargo, evidence showing that the vessel ventilated correctly may be instrumental in defending any ensuing claims. Such evidence can be found usually in the Deck Log Book and the Cargo Temperature and Ventilation Log.

1. Deck Log Book

The Officer of the Watch (OOW) is obliged to record all the events and abnormality (if any) occurred, including the prevailing weather condition, state of seas, etc. Hence, proper entry for cargo ventilation being carried out or otherwise at the material time should be made in order to safeguard the best interests of the owners/carriers in case such records are required to be disclosed as supporting documents at a later stage. Meanwhile, appropriate entries in the Deck Log Book should be written in most simple, clear and suitable wording to avoid incorrect interpretation by the claimants or unnecessary challenge or misunderstanding by the presiding judge.

2. Cargo Temperature and Ventilation Log

It is recommended that a separate ventilation log for each hold to be used to record all the required observations once per watch: dry & wet bulb temperature and the dewpoint of ambient and cargo hold (only dry temperature of ambient required if Three Degree Rule used) , cargo loaded at average temperature (if Three Degree Rule used), oil tank temperature, seawater temperature, bilge sounding (at least two times every day), times of ventilation starts and stops, remarks and comments.

It is important to realize that even if the ventilation procedures are properly followed and applied, sweat may still unavoidably form as there are still limitations to how effective cargo ventilation can be due to various factors such as weather conditions, fumigation, cargo characteristic and stowage status etc. Therefore, in order to show ventilation has been managed in a prudent manner, it’s essential to record all decisions and actions taken with regards to cargo ventilation during the voyage in remarks/comments column, especially reasons for stopping ventilation.

3. Other records: cargo declaration and cargo quality certificate, log of weather conditions, written instructions on ventilation from the shipper/charterer or the fumigator, records of sweat and evidence on relevant parties notified in a timely manner.

For more information, please contact Managers of the Association.