It is always a good practice to cover your own ass!! Expecting someone else to warn you of dangers gives them control over your life. It is always better to be in control of your own fate, finding someone else at fault has no effect on your injuries. When I am at the helm I try to warn anyone that''s in harms way but when I am in harms way I don''t expect to be warned. Intentionally or otherwise my wife has almost hit me with the boom several times. But by luck or skill I have always managed to avoid being hit. It is foolish to stand/sit in such a way that being struck by the boom is possible.