If your sailing is delayed or cancelled, the ferry company will always try to offer you an alternative sailing or a refund if there is no alternative. Depending on the reason for the delay/cancellation, you may also be able to receive some compensation.
Additional compensation is usually only possible when the ferry company is responsible for the delay/cancellation, so you will not receive any compensation for delays due to reasons beyond their control, such as bad weather and strikes. Because of this, we recommend purchasing travel insurance that will cover you for force majeure events.
If you're travelling in Europe, you can check the European Commission website to learn about your rights in case of delays and cancellations.