Final answer:
The correct signal blast for 'carry on' when rendering honors in a maritime context is one blast. This is part of naval etiquette to communicate between ships.
Step-by-step explanation:
When a ship is passing another ship and rendering honors, the specific number of signal blasts for 'carry on' is one blast. In the context of maritime operations, signaling is essential for communication and ensuring safe passage. The tradition of rendering honors via signal blasts has a rich history in naval etiquette, allowing vessels to recognize one another and communicate intentions without the need for verbal communication.