The Group had a contractual arrangement with a third party to share equally the operating result associated with the chartering of a vessel (joint operation). The amounts of income and expenses recognised in respect of the Group’s interest in the joint operation are as follow:
| US$'000 | 2018 | 2017 |
| Charter-hire income included in revenue | 4,614 | 4,600 |
| Charter-hire expenses included in cost of services | (3,389) | (3,388) |
| 1,225 | 1,212 |
Accounting policy
A joint operation is a contractual arrangement whereby the Group and other parties combine their operations, resources and expertise to undertake an economic activity in which each party takes a share of the revenue and costs in the economic activity, such a share being determined in accordance with the contractual arrangement.
The assets that the Group controls and liabilities that the Group incurs in relation to the joint operation are recognised in the consolidated balance sheet on an accrual basis and classified according to the nature of the item. The expenses that the Group incurs and its share of income that it earns from the joint operations are included in the consolidated income statement.