@futurebird It depends to some degree on the architecture of the boat, the geography of the part of the world where you plan to hang out, and the set of countries whose ports you can safely use as harbours, but 20 feet is probably not enough if where you're trying to hide from storms is the ocean at large and you plan to do it on a long, multi-year, basis.
There's a now confirmed to happen but poorly undersood mechanism that can cause occasional extreme waves, which could probably sink a 20-feet sailboat, and since the mechanism is not yet properly understood, there's currently no reliable way to avoid them.
If the body of water where you're hiding from storms is sufficiently small, as in, a lake (and preferrably, a smaller large than the Great Lakes) or a river or a canal system or a bay, that could protect you from extreme waves, but it could also complicate navigating to a place away from reliably prognosticated extreme wind events, when those happen, if your part of the world has them.
futurebird