> For the complete documentation index, see [llms.txt](https://docs.dataloy.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.dataloy.com/release-8.28/voyage-management-system/step-by-step-guides/vessels/maintain-opex-on-a-vessel.md).

# Maintain OPEX on a Vessel

Each vessel has its own OPEX list under the **Operating Cost** tab. Lines here represent the running costs specific to this vessel and are stamped onto the voyage when the vessel is assigned.

***

### Opening the OPEX List

Navigate to the Vessel record and open the **Operating Cost** tab. The list of OPEX lines for this vessel is displayed.

***

### Adding an OPEX Line

**1. Click Create** in the Operating Expenditure list.

**2. Enter the required fields:**

| Field                     | Description                                   |
| ------------------------- | --------------------------------------------- |
| **Opex Cost Code**        | Reporting code for this cost category.        |
| **Opex Cost Description** | Name of the cost, e.g. "Crewing", "Lube Oil". |
| **Daily Rate**            | Cost per day in the OPEX currency.            |
| **Currency**              | Currency of the rate.                         |
| **From Date**             | Start of validity.                            |
| **To Date**               | End of validity.                              |
| **Stock Account**         | Accounting stock account reference.           |
| **Cost Account**          | Accounting cost account reference.            |
| **Comment**               | Optional free text.                           |

**3. Save.**

***

### Editing and Deleting Lines

All columns are editable in the list except Opex Cost Code. Select a line and click Delete to remove it. Removing a line from the vessel does not affect OPEX lines already stamped onto existing voyages.

***

### Stamping onto a Voyage

When a vessel is assigned to a voyage, the system stamps the vessel's OPEX lines onto the voyage. If the vessel has no OPEX lines, the system falls back to the Vessel Type's default OPEX lines.

> **Important:** Stamping is a one-time copy. Changes to the vessel's OPEX after the voyage has been created do not cascade to the voyage automatically. Voyage-level OPEX lines must be managed directly on the voyage.


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