US-based workboat operator Gulfmark Offshore has elected not to make a $13.7 million interest payment due this week as it hurtles towards default on its debt.

The struggling company is now in a 30-day grace period that ends 15 April. If Gulfmark does not make good on its senior notes payment by then, it will be in default, the company said in a securities filing.

The company had $473 million in total debt as of the third quarter of 2016, and $10 million in cash.

Gulfmark