on account of the greater outreach necessitated by the fitting of external buoyancy. SECTION C.-CONSTRUCTION OF CLASS III. BOATS THE midship section of a Class III. boat is illustrated in Fig. 7. This type of boat is constructed in a similar way to an open lifeboat of Class IA, with this exception, that buoyancy air-cases are not fitted. The construction is practically confined to the "clinker " method. They very rarely exceed 22 ft. in length; in reality they are light pulling boats, and it is quite probable they are used with greater frequency than the larger lifeboats carried on board a cargo vessel. Passenger vessels are not permitted to carry boats of Class III. In a foreign-going steamship, not certified to carry more than twelve passengers, and certain other vessels mentioned in Section A, Part II., a proportion of the total number of boats to be carried may be of Class III. As an example, in the case of the foreign-going steamship referred to, if the total number of lifeboats required by the Life-saving Appliances Rules exceeds two, a boat of Class III. may be carried in lieu of one of them, and if the number exceeds three, one or two boats of Class III. may be carried in lieu of the same number of lifeboats. The Class III. boats as well as the Class I. lifeboats, should be attached to davits. It is important to remember that when a vessel is certified to carry a number of passengers, not exceeding twelve, and which, if it were not certified to carry passengers, would be subject to rules governing foreign-going steamships not certified to carry passengers, or a steamship trading within home trade limits, but not certified to carry passengers, as the case may be, it is subject to the rules governing the boats for the latter classes, and not to those in any other class. Under these conditions a certain number of Class III. boats may be carried, but steamships certified to carry more than twelve passengers, must have buoyancy air-cases fitted to the whole of the open lifeboats carried on board. Every boat which is carried on board a' vessel is classified, provided that it forms a part of the statutory equipment of the vessel. Boats which are carried in addition to the equipment, such as working boats or the captain's dinghy, need not be classified. Class III. boats must, therefore, be built under inspection, and conform to all the regulations issued by the Board of Trade as to scantlings and details of construction. In the case of defective planking or damage, a Class I. lifeboat possesses the buoyancy air-cases as a secondary means of keeping her afloat, but the Class III. boats depend entirely upon the quality of material and workmanship for maintaining herself in a seaworthy condition. Hence, the importance of careful scrutiny during the progress of construction. Some builders are inclined to look upon these boats as being of less importance than the lifeboats, but, strictly speaking, they should be constructed with even greater care than the larger boats. There are bound to be anomalies in all rules, but many people cannot understand why it should be necessary in the case of a small sailing vessel, say a ketch of 40 tons gross tonnage, and running between Glasgow and Ayr, carrying an open boat of Class III. sufficient to accommodate all persons on board, should, immediately a small motor is inserted as an auxiliary means of propulsion, be required by the Life-saving Appliances Rules to carry a lifeboat of Class 1., i.e. buoyancy air-cases must be fitted to the Class III. boat. The installation of a motor has converted the sailing vessel into a steamer and brought her under a new classification of the L.S.A. Rules, but the necessity does not appear clear. It is important to remember that all Class III. boats must be equipped in every detail the same as the Class IA lifeboats carried on board. In 16-ft. boats and below, it is not usual to fit side seats extending over the whole of the thwarts as in a lifeboat of Class I. of similar dimensions. The amount of equipment which must be carried in accordance with the regulations is sufficient to limit the number of persons which can be reasonably assigned to the boat. Very few boats of Class III. are constructed "double bowed," they usually have square sterns which allow greater accommodation on the stern benches. In boats of 18 ft. in length and upwards it becomes necessary to extend the seats in order to provide sufficient area for seating. SECTION D.-CONSTRUCTION OF CLASS IIA OPEN LIFEBOATS WITH COLLAPSIBLE BULWARKS A GENERAL description of the differences between the various types or classes of boats, has already been given in Section B of Part II., and the purpose of grouping the various sections under Part IV. is to provide discussion, in fuller detail, of the methods of construction in each individual class of boat. Fig. 4 gives, in outline, the midship section of a Class IIA open lifeboat, and it will be seen that it differs in form from the ordinary type of open lifeboat (Class I.), having a much lower freeboard to the top of the solid hull. Additional protection is obtained by the fitting of collapsible bulwarks. Comparing boats of the same length but differing in class we find that the freeboard of a 28-ft. lifeboat of Class IA is about 24 in., and that of a 28-ft. lifeboat of Class IIA is 9 in. measured to the solid hull, but with the bulwarks fixed in position, is increased to about 33 in. The provision of collapsible bulwarks allows this type of boat to be stowed under open lifeboats of Class I., which are attached to davits, or they may be stowed inboard one above the other or singly, provided transporting arrangements are fitted under the boats to bring them under the davits with rapidity, for launching overboard. This class of boat appears to find most favour with shipowners who require to be supplied with a number of lifeboats having collapsible bulwarks. The lengths of the boats vary from 24 to 30 ft., the breadths from 8 to 9 ft., and the depth without bulwarks is about 2 ft. Watertight metal air-cases are fitted at the sides in a similar fashion to Class I. boats, in order to provide the necessary reserve of buoyancy. The general structure of the hull is made up of two thicknesses of wood planking, worked in a fore-and-aft direction, and so arranged that the seams of the two thicknesses break joint one with the other. An approved fabric is worked between the two thicknesses of planking. For vessels whose trade continually takes them through the tropics, it is very essential that the planking should be of material that is least affected by the extremes of temperature. Two thicknesses of Honduras or Lagos mahogany make an excellent hull, and it is the opinion of many, that wood of inferior quality to mahogany should not be permitted in these classes of boats, as they are not used or inspected with the same frequency as Class I. boats of the open type. In cases where passenger vessels are constantly employed in a temperate climate, the double thickness of wood planking is sometimes made up of an inner thickness of larch and an outer thickness of yellow pine. The boat is double bowed, having a "deck" at the ends and over the buoyancy tanks at sides, with a central open well the full depth of the hull. The deck, or covering, over the buoyancy tanks forms the upper surface of the hull from which the freeboard is measured. Above the "deck" are fitted the collapsible bulwarks, which hinge down in their stowing position. The standard type of Class IIA lifeboat at one time consisted of the hull as described, with solid wooden bulwarks fitted for a little more than half the length of the boat amidships, in way of the straight sides. Between the wooden bulwark and the ends of the boat rotproof and waterproof canvas was fitted. The bulwarks were kept in position by hinged stanchions, which locked themselves in the upright position. Thwarts were also fitted and arranged to hinge down in a similar way to the bulwarks. They were connected together in two sections, so that the forward section would hinge towards the stem and the after section towards the stern. Locking arrangements were also provided for the thwarts. The first operation is to lift the bulwarks and then the thwarts; when the latter are in position and persons seated thereon, movement cannot take place; the upper structure is thus well secured. Outside buoyancy made up of solid cork and secured by the method described in Section B, is fitted on each side of the boat, immediately above the water-line. Fig. 114 shows the old standard type of Class IIA open lifeboat, undergoing the Board of Trade rowing tests, with the full number of persons on board, each one being provided with a life-jacket. This type of life-jacket has now been condemned. The particular boat illustrated was constructed by Messrs. Hugh McLean and Son, of Govan, who have had a very extensive experience in this and other types of lifeboats with collapsible bulwarks. The following details of construction are given for a lifeboat of standard size, viz. :— Scantlings. These are based upon the assumption that the structural strength is such that the boat will be able to support a deadload equal to 25 per cent. greater than the actual service load, when supported by the slings and their attachments. |