Best answer for how long to boil ribs: around 1 hour.
There are two reasons or styles of boiling ribs. The first way is to boil the uncooked pork or beef ribs followed by placing them on the grill. The boiling is used to cut down the time it will take for the ribs to cook on a grill. If this is your reason for boiling the ribs, please regard the following directions. Bring a large pot of water to a roaring boil. Once the bubbles escape the surface of the pot, place your seasoned or unseasoned ribs into the pot, cover and reduce the temperature to medium. Salts are recommended for the water but you can also add any vegetables or additional flavoring. Remember, the water will absorb most of the seasoning in the end. The actual boiling time will vary depending upon the size of the rack of ribs and if they are beef or pork but the general rule is to leave them in the pot for about 45 minutes. Adjust according if you have more or less meat (use your own judgment). Drain and remove the ribs before seasoning or rubbing them and place them on the low heat grill for an additional 20-30 minutes per side depending on desired level of tenderness.
The other style of boiling ribs is to cook the entire rack underwater. This method loses a lot of flavor, fat, and nutrients into the water. This is the fastest method of cooking ribs, but many purists will denounce this method. However, if you are short on time, drops your ribs into salted boiling water for 1 to 2 hours depending upon the size and amount of ribs. There is not an exact cook time but how long the average rack of ribs should take to boil is about sixty minutes. Check for tenderness and level of doneness and adjust accordingly. The USDA suggests that pork ribs are safe to eat at 180 degrees Fahrenheit.