I have never found that their ignorance of "nautical language" is a problem when I have lubbers in my boat. The reason is that I "single-hand" regardless of the number of lubbers I may have aboard, so the safety
of the vessel and/or the "crew" (passengers) isn't jeopardized by a lubber's failure to understand simple stuff like "Gybe-HO!". More significantly, the safety
of the vessel isn't jeopardized by MY relying on a lubber to do what I had no right to expect that he would know how to do. Since sailing, like war, consists of long periods of utter boredom punctuated by moments of utter terror, there is plenty of time to teach during the long intervals with "nothing to do".
This is actually one of my standard teaching devices: As we are broad-reaching along on the first day out, I'll say "Jenny, please sit down, cos if you don't that big lump of wood there (I point to the boom) will smack you on head
, and I guarantee you, you won't like that!" Then, when Jenny has sat down, I bring the boom over with as much conviction as the rig will stand. This is the perfect and effective intro to my canned spiel on knowing "funny words, like 'boom'" being a safety requirement, "so we'd better learn them". This, then, ties the day's "practicum" together with the evening's "classroom lecture" on nautical terminology and safety afloat.
But teaching boat handling is like teaching accounting — They won't learn unless you make them laugh :-).