INTERNATIONAL CONVENTION SAFETY OF LIFE AT SEA. 223 



(3) The results of experiments in regard to the proper margin of resistance a"bove the 

 pressure which watertight bulkheads are required to be capable of supporting, as referred to 

 in Article XIV of the annexed Regulations. 



The contracting States undertake to exchange all information as freely as possible in re- 

 gard to the application of the rules of this Convention in matters relating to safety of 

 construction. They shall communicate to each other the methods or rules which they adopt ; 

 information concerning any new fittings or appliances which they sanction; the decisions 

 which they make in regard to points of principle not covered by the foregoing articles and 

 the corresponding portion of the annexed Regulations ; and the final results of their further 

 studies in matters not definitely determined. 



Chapter V. — Radiotelegraphy. 

 Article 31. 



All merchant vessels belonging to any of the Contracting States, whether they are pro- 

 pelled by machinery or by sails, and whether they carry passengers or not, shall, when en- 

 gaged on the voyages specified in Article 2, be fitted with a radiotelegraph installation, if they 

 have on board 50 or more persons in all. 



Advantage may not be taken of the provisions of Articles 2 and 3 of this Convention to 

 exempt a vessel from the requirements of this chapter. 



Article 32. 



Vessels on which the number of persons on board is exceptionally and temporarily in- 

 creased up to or beyond 50 as the result of force majeure, or because the master is under the 

 necessity of increasing the number of his crew to fill the places of those who are ill, or is 

 obliged to carry shipwrecked or other persons, are exempted from the above obligation. 



Moreover, the Governments of each of the Contracting States, if they consider that the 

 route and the conditions of the voyage are such as to render a radiotelegraph installation un- 

 reasonable or unnecessary, may exempt from the above requirement the following vessels : 



(1) Vessels which in the course of their voyage do not go more than 150 sea miles from 

 the nearest coast. 



(2) Vessels on which the number of persons on board is exceptionally or temporarily 

 increased up to or beyond 50 by the carriage of cargo hands for a part of the voyage, pro- 

 vided that the said vessels are not going from one continent to another, and that, during that 

 part of their voyage, they remain within the limits of latitude 30° N. and 30° S. 



(3) Sailing vessels of primitive build, such as dhows, junks, etc., if it is practically 

 impossible to install a radiotelegraph apparatus. 



Article 33. 



Vessels which, in accordance with Article31 above, are required to be fitted with a radio- 

 telegraph installation are divided, for the purpose of radiotelegraph service, into three classes, 

 in accordance with the classification established for ship stations in Article XIII (b) of the 

 Regulations annexed to the Radiotelegraph Convention, signed in London on the 5th July, 

 1912, viz. : 



