The preferred method of cooking lobsters.

Steaming is my preferred method of choice as it is gentler, yielding a slightly tender flavorful meat and it is more forgiving on timing.  It's harder to overcook a steamed lobster. A 4-5 gallon pot will handle 4-6 lobsters.  Put 2" of salted water in the pot, then a steaming rack and bring to a boil.  Add lobsters one at a time and cover.  Start timing 18-20 minutes depending on the doneness preferred.  Timing is for ALL the 1-1/2 lb lobsters in the pot. When cooking five or more, mix up lobsters halfway through and cover.

For boiling lobsters, fill the pot with 3" to 4" of salted water, bring to a boil and add lobsters and start timing immediately.  Do not cover.  Boil lobsters 20 - 23 minutes.