If I'm reading correctly, that 9.9 hp Yamaha is about 90lbs. I do think it's too heavy for a weight sensitive 16 angler. The transom would hold it ok, but, with your swim step on the port side and the driver and batteries on the starboard, adding another 90 pounds to the starboard side would cause significant list. I have a 5 hp. Honda. It's a good motor, and it will push the boat at about 5mph and use negligible gas. It weighs about 60 lbs. If I had a choice I would seriously consider the Honda 2.3hp (30lbs) or maybe the Tohatsu 4hp (43 lbs). All these kickers will push the angler along at 3,4, or 5 mph. None, including the Yamaha, will plane the boat. If you search this site you will find quite a bit of relevant discussion.