The trailer is the big variable here, but the my 20' pontoon boat weighs about 1600 pounds with all the furniture on. The trailer will probably weigh about 1600-1800 if it's made of steel, so about 3200 lbs is probably about right. The trailer is the big variable here, but the my 20' pontoon boat weighs about 1600 pounds with all the furniture on. The trailer will probably weigh about 1600-1800 if it's made of steel, so about 3200 lbs is probably about right. Minor edit?