60 HP merc 4 stroke on a pontoon. With a 4 blade Quicksilver 13.8 - 10 with a normal load ( me and the wife and our fishin gear) I hit 6100 WOT. With a13.8-11 I hit 5480. So if I add a little weight ( the dogs and some friends ) the 10" would be under 6000 and the 11" would be "lugging". I am guessing I would be better off NOT lugging the motor and go with the 10". Of course I never run WOT.
