Welcome to sailing. Half tonners are a type of race boat designed to race under the IOR, an now obsolete rating rule. While I am not familiar with the Adams per se, the IOR of that era generally produced pretty unseaworthy and difficult boats to handle. Generally they don''t make very good cruisers as they tend to be pretty spartan and are not terribly robust. They are also difficult boats to race requiring comparatively large crews and sail inventories.