I have 22 ft. with 40 hp Bigfoot merc. The other day I had a boatload of of teens and was pulling a tube. It pulled the tube, got it to plane on the water but no whipping it around like a ski boat would. With 10 on the boat and 2 in the tube we were hitting around 12-13 mph. The kids were board until they started battling to see who could knock the other one off the tube. The girls kinda liked just being back there getting pulled around and small kids would think it was fun too.
As for flat out speed, before the kids got on the boat I was running 18.3 mph (GPS reading).
I was also pulling some kids on the tube last weekend. I have a 24' with a 50HP Johnson.. 8 on board, pulled a tube at 12 Knots GPS.. Not too bad, but as mentioned, not as fun as a ski boat. The kids had a good time!
I rented a 20 footer with a 40 on it during my vacation. It was slow. I have a 24 footer 60HP BF 2-cycle on mine, and it measures 18.7 full out (GPS). my kids are teens and wants at least 20MPH. so a 40 will not make them happy. ( But you go forever on a tank of gas!) I have a speed boat for tubing.
I have a 21 footer with a 90hp and we were getting 26 mph (GPS) with 3 adults and 3 kids on board....and that was in some very choppy waters of Lake Monroe, IN.
