http://books.google.co.nz/books?id=fkx2m_5fjyIC&pg=PA255&lpg=PA255&dq=greater+body+mass+downhill+ski+racing+advantage&source=bl&ots=Lmy1HYla8H&sig=l8SzPuHptEhFIn4geCQNF4ymmQE&hl=en&ei=AwCxTP_CJYyWsgPI_ZSwDA&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEQQ6AEwCA#v=onepage&q&f=false
With surfing the situation is slightly different as the proportion of air drag to surfboard ( water) drag is lower than the proportion of air based drag to ski based ( snow) drag is with skiing.
From this we can deduce that the advantage in terms of drag reduction which a heavier board and rider combination has is greatly increased when surfing against the wind. This is because when surfing against the wind the proportion of air drag to water drag increases.
It is also interesting to note that rider posture has a big effect on air drag. . . upright postures are markedly less efficient. That's why I crouch when speed increases, even though correct 'style' might demand a more upright pose.
