How much wind acn a tripping canoe

how much wind
I have a kevlar canoe and the other day myself and two daughters took a short trip up the river to the beach, where we picniced. For the return trip the girls wanted to swap seats. Angela, the large girl , sat in the bow, and Jennifer, the small girl, sat in the middle. I was Captain. With this configuration the first little wave that hit us send us over. I grabbed the rope to stop the canoe getting away and the rope snapped-it was old. We pushed the boat to shore but it took quite awhile. I learned many lessons that day. One is inspect your equipment and another is put the heaviest person or thing in the middle.