I used 6 teal decoys and it seemed to work. 
 

At shooting light a ring neck buzzed by and took her. I wish I wouldn't because it scared off a group of 7-10 teal swimming towards my decoys. Had pintail come but I missed. 
 

If you don’t have a dog or the motor for the boat, putting out decoys will be challenging. The soil is extremely soft, and you’ll sink in just one foot off shore.