Some of us, the coffee drinkers, may be happy to note that, recently, the charterers rewarded one of our commercially managed vessel with a cappuccino machine to thank the crew for looking after their interests. However, in this case the “Cappuccino Effect” has nothing to do with coffee but with the supply of bunkers.


What is The “cappuccino effect”?

The effect is created when the bunker supply barge introduces air into the supply line during and/or after bunkering operations, which results in/leads to the development of froth and foam on the surface of the bunkers in the bunker tanks of the receiving vessel. This increases the volume of the fuel and results in exaggeratedly high volumetric flow metre readings. The flow metres will measure the volume of the product that passes through them (including the air bubbles).

When tank soundings are taken after the supply of bunkers, the results indicate a higher amount of fuel than was actually received. Once the froth/foam dissolves, the actual quantity can be measured, leaving the receiver with a shortfall in bunkers. In large deliveries of bunkers, this may lead to substantial losses for the receiver, in particular in a high bunker price market.


Cappuccino Effect (froth / foam on top of fuel)

capEff-03.pngHow the surface of the fuel oil should look like

If the cappuccino effect is not noticed during the bunkering operation, it may be too late to recover such losses afterwards as the vessel may have already sailed or even commenced consuming the bunkers in question. The presence of one or more of the following factors may indicate that fuel supplied to the vessel contains an excessive amount of air:

  • Foam and/or frothing on the surface of the fuel oil on the barge prior to bunkering
  • Any suspicious connections to the bunker barge supply pump and supply pipework prior to pumping
  • Unusual gurgling noises from the supply line or at the manifold
  • Variations in line pressure at the manifold
  • The sounding tape is found to be covered with air bubbles

The case of the “Cappuccino Machine”

Charterers of the vessel, had ordered 1,000 metric tons of HFO 380CST to be supplied to the vessel in Singapore. During the bunkering operations the crew noticed a peculiar sound coming from the bunkering hose and they became more vigilant. After the bunkering operations, the crew measured the quantity of bunkers received, and when they observed air bubbles on the sounding tape, they immediately issued a Note of Protest for Cappuccino Effect. After 24hrs, further soundings were taken which proved a bunker shortage of 60 mt.

capEff-04.pngSounding tape with air bubbles


Sounding tape without air bubbles

The charterers protested and refused to pay for the full quantity of bunkers as indicated by the supply barge. With an average cost of US$ 600 per metric ton, the charterers thus saved approximately US$36,000. To show their gratitude to the crew, the charterers rewarded them with a coffee/cappuccino machine, so they could enjoy good and genuine cappuccino on board.

How to avoid The “cappuccino effect”

There are various precautionary measures that the crew can take in order to avoid such fraudulent practices by bunker suppliers.

The vessel’s crew should inspect the line blowing arrangements on the bunker barge before bunkering commences. Upon completion of bunker delivery the crew should ensure that the bunker barge strips the empty tanks and blows the bunker transfer lines properly. The temperature of the fuel oil should be measured before the transfer in order to calculate the fuel oil density accurately. The crew of the receiving vessel should look for foam and/or frothing on the surface of the fuel oil on the barge prior to bunkering, and on the vessel upon completion of bunkering operations. While taking soundings on the bunker barge or on the vessel, check for air bubbles on the sounding tape or brass bob. Check the density of the fuel oil received if a portable density meter is available onboard A lower density than expected, taking into account any temperature change, may indicate the presence of air. Line blowing by the barge should only be permitted on completion of bunkering, after quantities delivered have been checked. When a large quantity of compressed air is passed through a hose containing fuel oil, the hose may tend to jolt or shudder, therefore monitoring the supply hose for unusual movements and abnormal sounds is an indication of fraudulent practices.

A detailed record of times, soundings, quantities, temperatures, densities and other key information should be maintained in case of any dispute. For the same reason, photos and videos should be taken.

Although bunkering disputes are difficult to resolve, the suppliers count on the vessel not to dispute the quantities. The vessel’s prompt actions to prevent or record such fraudulent practices make the difference in winning such disputes. If and when “Cappuccino Effect” is observed, the Master should immediately inform all parties concerned, i.e. owners/charterers/managers to take all necessary steps. The Master is to issue a Letter of Protest and refuse to sign the Bunker Delivery Note until he receives further instructions. These steps are essential to protect the owners’/charterers’ interests. Any delay may weaken the owners’/charterers’ position to the supplier ending up in monetary losses.