Spinnaker Mainsail

[colo.sail]

I thought the guy was crazy.
First he dropped his main, attached a spinnaker to the main halyard, clew to the foot and the second clew line ran through the end of his boom.
Raised the spinner, eased out the mainsheet and controlled the sail with the spinner sheet via the boom end.

He took off. Soon even gybed and continued.

Is this normal practice or just a lazyman's way of using an undersized spinnaker on a cruising boat?

[Blue Stocking]

Vintage Assymetrical