[Code of Federal Regulations] [Title 33, Volume 1] [Revised as of July 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 33CFR86.23] [Page 219] TITLE 33--NAVIGATION AND NAVIGABLE WATERS CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PART 86_ANNEX III: TECHNICAL DETAILS OF SOUND SIGNAL APPLIANCES--Table of Contents Subpart B_Bell or Gong Sec. 86.23 Construction. Bells and gongs shall be made of corrosion-resistant material and designed to give a clear tone. The diameter of the mouth of the bell shall be not less than 300 mm for vessels of more than 20 meters in length, and shall be not less than 200 mm for vessels of 12 to 20 meters in length. The mass of the striker shall be not less than 3 percent of the mass of the bell. The striker shall be capable of manual operation. Note: When practicable, a power-driven bell striker is recommended to ensure constant force.