Live report: High drama on the high seas in MH370 search

After the long-awaited departure of the Ocean Shield, the three-day journey to the search zone of missing flight MH370 was interrupted within minutes of leaving Stirling Navy base.

A vessel broke down in the shipping lane out into the Indian Ocean, forcing the Ocean Shield to stop.

7News Investigations also responded to the distress signal and towed the stricken boat to safety.

The vessel is due to begin work in the search zone on Thursday.

Even though it's carrying very best equipment of this kind in the world, unless that search zone can be narrowed it will be almost useless, the equipment is only designed to search an area the size of an Australian city, not an entire state.

Nevertheless, it will deploy that Towed Ping Locator and start work the moment it arrives, because the black box may only be giving a signal for a matter of days.