Cover the steamer basket with a tight-fitting lid and place on top of the stockpot with the boiling water and steam until the batter pulls away easily from the husks, checking occasionally to see if the pot needs to be replenished with water, about 1 hour total.
When heating the water to cook the tamales, drop a clean coin in the pot. As the water boils, the coin will rattle, letting you know that the water has not boiled dry. If the coin stops rattling, you know that it’s time to add more water. Or just set your iPhone timer for every 10 or 15 minutes and check the water level.