Actually there is two ways to deal with heavy weather conditions. Traditionally heavy displacement was the preferred method. This was the build it so tough that nothing can do it any harm and then let it survive on its own abilities to avoid being bashed to a pulp. The second approach counts on an easily driven hull form and an easily manageable rig
. While this approach existed in traditional forms (Tancock whalers for example) it is really been developed much more comprehensively in recent years.
The key elements of this approach is a light enough displacement that the boat has a low wetted surface, and a hull form inteded so that the boat rides over rather than colliding with waves, high ballast stability and a low VCG, moderate to low form satbility, efficient foils, sophisticated engineering so that the boat has the necessary strength to withstand an assault without damage but light enough to have a decent ballast to weight ratio and adequate carrying capoacity. A long waterline length helps with seakindliness because it can reduce pitching, allows a boat of equal displacement to be easily driven, and reduces the depth of the canoe body which helps with ballast stability and foil efficiency.
Interestingly enough, an easily driven hull form also results in better light air performance.
The worst case having poor performance at both extremes is the case of a heavy displacement cruiser where much of its weight is located in interior furnishings, heavy decks (either teak or solid cored), and heavy spars and rigging
. This is especially bad when the company uses low density ballast and a long keel. You end up with a boat that in heavy going requires a lot of drive to keep it going but does not have the stability to stand up to its rig
. Similarly the large drag associated with boats like these make them poor light air performers.