You do mean a 19ft angler since its a 2006 model (1650lb) with a 115 optimax you could run a 13 1/2 by probably a 19pitch maybe even a 21 pitch prop . what prop do you have now or if engine is new or new to you then go to a prop shop and borrow a few props and take her out and see which one runs up at WOT to your max rpm for your engine 5000=5750 rpm? check engine specs.
A friend of mine had a 22 angler about 150lb heavier and he ran a 115 Suzuki (Suzuki have a larger gear ratio than most other engines ) with a 20in pitch and he could run WOT about 38mph a little to squirally for a c-dory Good Luck Jim
