also be provided with a sufficient supply of red pyrotechnic lights, which shall each burn for at least thirty seconds and shall be shown on the approach of or to other vessels in sufficient time to prevent collision.

  In the Mediterranean Sea the vessels referred to in subdivision
  (b) 2 may use a flare-up light in lieu of a pyrotechnic light.

  All lights mentioned in subdivision (b) 1 and 2 shall be visible
  at a distance of at least 2 miles.

Third.  If sailing vessels of less than 7 tons gross tonnage, shall not be obliged to carry the white light mentioned in subdivision (b) 2 of this article, but if they do not carry such light they shall have at hand, ready for use, a lantern showing a bright white light, which shall on the approach of or to other vessels be exhibited where it can best be seen in sufficient time to prevent collision; and they shall also show a red pyrotechnic light, as prescribed in subdivision (b) 2, or in lieu thereof a flare-up light.

  (c) Vessels and boats when line fishing with their lines out and
  attached to their lines, and when not at anchor or stationary, shall
  carry the same lights as vessels fishing with drift nets.

(d) Fishing vessels and fishing boats may at any time use a flare-up light in addition to the lights which they are by this article required to carry and show.  All flare-up lights exhibited by a vessel when trawling or fishing with any kind of drag net shall be shown at the after part of the vessel, excepting that if the vessel is hanging by the stern to her fishing gear they shall be exhibited from the bow.

  (e) Every fishing vessel and every boat when at anchor shall
  exhibit a white light visible all around the horizon at a distance of at
  least 1 mile.

(f) If a vessel or boat when fishing becomes stationary in consequence of her gear getting fast to a rock or other obstruction, she shall show the light and make the fog signal prescribed for a vessel at anchor, respectively. (See article 15 (d), (e), and last paragraph.)

(g) In fog, mist, falling snow, or heavy rain storms drift-net vessels attached to their nets, and vessels when trawling, dredging, or fishing with any kind of dragnet, and vessels line fishing with their lines out shall, if of 20 tons gross tonnage or upward, respectively, at intervals of not more than one minute make a blast—­if steam vessels, with the whistle or siren, and if sailing vessels, with the fog horn—­each blast to be followed by ringing the bell.

(h) Sailing vessels or boats fishing with nets or lines or trawls when under way shall in daytime indicate their occupation to an approaching vessel by displaying a basket or other efficient signal where it can best be seen.

  The vessels referred to in this article shall not be obliged to carry
  the light prescribed by article 4 (a) and article 11, last
  paragraph.