Yesterday I went sailing in 15+ knots and serious waves for an inland lake and because I have mainly sailed in winds up to 15 knots, I still find this very challenging. Upwind is fine, but I have difficulty changing course to a broad reach, while keeping the boat under control. I earlier understood that oversheeting on a reach slows the boat down, but I find it hard to get on and keep it on a reach. If I ease the sheet too much the boat takes off like a rocket. Gybing is also very challenging. I now the only way to master this is doing it, but it is not something I look forward to, to say the least.