You sure do, or at least I believe that you do. That doesn't change the fact that in order for the boat not sink, it has to displace slightly more than the weight of water equivalent to the weight of the boat plus all of its occupants. For any given boat, if you put more weight in it, it must displace more water (or be able to provide additional dynamic lift, but that's irrelevant for rowing sculls). Your boat and your boyfriend's boat have approximately the same freeboard, but his boat absolutely must have additional volume displaced below the waterline, and that necessarily induces additional drag.