I don't think that 20-25 degrees would be considered common today. But in yesteryear with wind power, small ships, large waves, I wouldn't doubt it. We went through a typhoon heading for Okinawa in the Spring of 65 and our old troop ship listed at 25 degrees during the heart of the storm. The sailors said that at 28 degrees we'd tip over. All I know is that a lot of guys were sicker than sick during it! And it was tough to navigate around the old tub.

Steve