# Canal Laytime Calculations
Starting with release 8.10, the system lets you create a laytime calculation for a canal passage; once created, you can add the time allowed and any deductions to register canal demurrage. The time allowed, as well as any time deductions, will not affect laytime calculations at other ports.
Note: As soon as a canal is included, the calculation is marked as ***reversible***, and you ***cannot*** change the **aggregation type** unless you first remove every canal entry from the calculation.
## Creating a Canal Port Laytime Calculation
To create a canal calculation you must select the canal itself in addition to at least one port **before** it and one port **after** it. For example, in the figure below, Bergen and Singapore must both be chosen as well as Suez Canal.
Figure 1: Show Canals filter active.
Figure 2: Suez Canal Laytime Calculation
## Removing a Canal Port Laytime Calculation
To remove a canal calculation, locate the canal’s section header and click the trash-can icon at the top right. A confirmation popup will ask you to confirm the removal; once confirmed, the canal entry is deleted and its demurrage is deducted from the total.
Figure 3 : Remove Canal Confirmation Modal
## Adding Time Not To Count
Adding time not to count can be used to control the time used, and therefore, the incurred demurrage. To add one, locate and click, the blue plus-button in the top-right of the Time Sheet. This will open a modal where you can enter the time not to count. To improve the process of adding time deductions, a new days field has been introduced, as seen in the figure below.
Figure 4 : Add Time Not to Count Modal
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