Running one on a heron 18. Went with the Powertech NSR 14 pitch. Started with a 15 and had to swap to a 14 pitch. I considered the scd and went with the NSR based on the recommendation from Powertech. By myself with a full tank of fuel, 1 group 31 and 1 group 34 AGM battery, trolling motor, fishing gear, it will do 38/39 at 6200-6300 rpm. With 2 people I’m seeing 36-37 at slightly less rpm 6000-6100. Hole shot and top end improved with the 14. Talk to Marcus at Powertech. He’s super helpful. I’m super pleased with how it performs with the F70. On the 16 heron you should be able to run a little higher pitch.
I’m with Walter Lee on this....not sure of the HP limits on the Heron16....but I’m guessing Mel would discourage it. I have the 50hp Tohatsu on mine, and can hit 40mph when I’m riding solo. I have a Tohatsu 11 x 15 pitch aluminum prop. It’s plenty of motor for me. I think the 60hp Tohatsu weighs the same as the 50hp.
About a year or so ago I saw a used Heron 16 listed on BoatTrader that had an F70 on it. At 253 lbs it's similar in weight to some of the 60 hp options out there. I'm guessing that's the only reason they would put it on a heron 16 (within the capability of the boat to carry the weight).