function check_competition (form, button)
{
  if (!check_radio(form.answer, 3, "an answer!") || // >>> do not hard code!!!
      !is_empty(form.boat_number, form.boat_number.value, "boat number") ||
      !check_email(form.email, form.email.value))
  {
    event.returnValue=false;
    return false;
  }

  //alert ("All entries verified OK!");
  // how do I make this general, like document.form.submit() ?
  document.competition.submit();

  return false;
}