That will certainly help break a broody but will not completely get the job done with a determined broody. They need isolation with no nesting material. The cool water dips and air circulation under them help cool them off and helps break the broodiness.
You can get a small wire dog crate off Craigslist for cheap. It's a necessary tool if you are going to have chickens and don't want broodies to continue that behavior. It's time to bite the bullet and make the investment.