Originally Posted by jjtjr
Its all about displacement, length and beam.
I would suggest that to say that more accurately you would say, "It's all about waterline length, weight distribution, and hull shape.
As to the discussion about which is more significant roll or pitch, in light of the conversation above I would perhaps like to suggest this as compromise language revising my earlier post:
"The motion comfort of a boat on the anchor is most heavily impacted by both the roll motion characteristics, and the pitch motion characteristics, this later motion being especially significant on small boats, or boats with proportionately long overhangs."
Reading the posts above about the significance of roll vs. pitch, I can only respond that I understand that roll can be very significant in some circumstances. I have experienced that myself. But in my experience, the more common motion on the anchor has been pitch. Obviously, reading the descriptions above, that is not a universal shared experience. This is solely speculation, but perhaps it may be that the commenters have spent more time on boats of a size or with hull forms that have comfortable pitching characteristics so that the roll motion is the harsher and more apparent of the two.
But whatever the reality of the incidence of roll vs pitch the worst nights that I have spent aboard boats have been on older designs with longer overhangs which tend to pitch and roll through wider angles.