Stability
The next quality, which is of essential importance in a Life-boat, is lateral stability, commonly called stiffness, being the tendency to preserve an upright position in the water, and proportionate resistance to upsetting sideways. This property is, of course, held in common by all boats, but is more especially essential to Life-boats, they being more exposed to the risk of upsetting than any others.
Stability may be obtained by three modes : – 1st. By great breadth of beam ; 2nd. By occupying the interior with air cases, as described already, in such a manner as to leave no space for water to remain in the interior, into whatever position the boat may be thrown, or So to confine it to her central part that it cannot fall much to one side above the centre of buoyancy ; and 3rd. By ballast.
In the self-righting Life-boats of the Institution very great stability is obtained by an iron keel, and other ballast, and by flatness and length of floor, with moderate beam only.
Richardson’s Tubular Life-boat has a great amount of stability, as will be seen by the following brief account of that boat. It is altogether different in principle to any other boat, and consists of two long tubes running parallel to each other a few feet apart, having their ends turned upwards and inwards, and terminating in points, with an open-work or grating-deck with corresponding thwarts, all supported above the tubes. It was designed and brought out by Messrs. H. & H. T. Richardson, two Welsh gentlemen, father and son. They had for many years a small boat of the same class in use on a lake in Wales, and when the Duke of Northumberland offered the prize for the best design of a Life-boat in 1850, they sent a model to compete for it. With much public spirit they then built, at Manchester, a full-sized boat, forty feet long, and rowing fourteen oars, and made a coasting voyage in it themselves from Liverpool to the Thames, putting into most of the intermediate ports.
The Tubular Life-boat, built by the Messrs. Richardson in 1851, was afterwards sold by them to the Portuguese Government, to be stationed at the City of Oporto, off the port of which there is a very dangerous bar.
Another somewhat smaller tubular boat was, in 1856, built for the National Life-Boat InstitutIon, and stationed at Rhyl, the boatmen at that place having applied for such a boat. She has since that time saved several wrecked crews, and has been highly reported on by those who work her. She has necessarily very great stability, and tows steadily.
Another such boat has been stationed by the Institution at New Brighton, and has done good service. in saving life and property. Mr. RIchardson, Sen, died many years ago ; but his son’s interest in humane work is unceasing.
Speed
A sixth and most essential property is speed. We say most essential, since without speed, or capability of being propelled against a heavy sea and head wind, the safest boat in the world would be useless. as she could not be conveyed from the shore to a wreck, frequently against a series of breakers of the most formidable description. As in ordinary boats, propelled by oars, the greatest speed can be obtained by sharpness of bow, and, within certain limits, narrowness of beam. Here, however, the similarity ceases ; for whereas great lightness is an advantage in perfectly smooth water and calm weather, weight – as stated under the head of Ballasting and Self-righting – is essential in a heavy sea, and especially in a broken sea, in which the light boat will lose her way, or be beaten back by each heavy sea as it strikes her, whilst the heavier boat will be, by her own inertia, carried away through or over the seas. In a Life-boat height. of bow and stern is also necessary to prevent the seas from breaking over and filling the boat for, if sharpness of form be preserved quite up to the gunwale, the height of end will not check a boat’s way so much as will a sea breaking into and half-filling her.
Again, the greater the length of a boat in proportion to area of midship section, weight being the same, the greater will be her momentum, and the faster will she be propelled against a head sea. The proportion of four feet of length to one foot of width of midship section is that which is adopted by the National LIfe-Boat Institution in its double-banked rowing-boats. In its few single-banked boats, which are stationed at places where larger and heavier boats could not be managed, still less proportional width is given.
Speed is not, however, alone essential in enabling Life-boat to force her way through the lines of breaking seas which form an almost impassable barrier between lee shore and a wreck. We believe that it also adds greatly to her safety ; for if she lose her way on meeting a very heavy broken sea or roller, she may not only be beaten back by it, but be thrown end over end or broadside to it, and be upset ; whereas if she retain her way, she can be kept bow to the sea until it has passed her, when she will again gather additional speed in readiness to meet with impunity the succeeding wave.
Stowage-room
A seventh quality is stowage-room for passengers. It is of course desirable that a Life-boat should have as large an amount as possible of stowage-room, as she is occasionally called on to go to the aid of large vessels or to proceed to the wreck of an emigrant vessel, or other passenger ship, when it is important that she should take on board a large number of persons so as to rescue the whole in as few trips as possible. The principal object in view therefore is to distribute the air- chambers, forming the extra buoyancy of the boat, in such a manner as to occupy no more than can be helped of any space which would be available for the stowage of passengers. Life-boats vary much in this respect, and it is a requirement which has been especially studied in the Institution’s boats.
Strength of build
The eighth and last quality which we have to consider is strength. As a Life-boat is liable to be thrown heavily on a beach by the sea, or to be knocked with violence against rocks or a vessel’s side, or to come in contact with spars or broken wreck floating in the water, she of necessity must be very strongly built ; and in this respect the Society’s boats will bear most favourable comparison with any others, as we have previously shown.
In connection with the last-named condition we may here state that most of the old classes of Life-boats are clinker or clench built, and of oak ; while the self- righting boats of the Institution are mostly built of mahogany, on the diagonal principle, which mode of build affords great strength and elasticity.