It is the latter type we are chiefly concerned with; how is it that the form has so deteriorated as to create this concern in our minds? I think the cause is not far to seek; it appears to be the outcome of (1) the shipowner's desire to carry the maximum number of persons in the minimum number of boats; (2) in the efforts of the ship-builder, as a rule, to carry out the specification in which he has contracted to supply the owners with boats at a price, often very low, and naturally he does not sublet his contract with the boatbuilder at a loss; (3) the aim of the competing boatbuilder, which is to build his boats at as little cost price as possible, and yet to provide accommodation for the prescribed number of persons. He is probably limited as to length, and therefore relies on the breadth and depth; in this direction, he is unintentionally assisted by the board's rule for measurement, viz, L B D .6/10 or 8; so long, therefore, as he can obtain his breadth at one point for measurement purposes, it is quite immaterial to him how soon he fines away to the ends, with the result that the stability of the boat becomes almost entirely dependent upon the form of a very limited midship section, or the still smaller proportion of same that would be under water when in the loaded condition.
The boatbuilder may be further restricted as to breadth, and, therefore, he again detracts from the form a boat should have by dispensing with sheer and increasing the depth from keel to gunwale amidships. This method of building boats enables him to obtain the capacity required by the owner at the expense of the boat's stability and utility.
No doubt when the life-saving appliances rules came into being the divisors 10 and 8 for the different sections were deemed safe on the supposition that the usual full form of boat would not be largely departed from. Experience has shown, however, that form is frequently sacrificed for the unworthy objects referred to above, and it follows, therefore, that either the form should be improved or a heavier divisor laid down.
It would, I think, be more effective to deal with form and devise a rule by which we can insure that a boat will be reasonably safe with its load, not merely in smooth water, as in our recent test, but in a seaway. It is essential, therefore, to draw the attention of the advisory committee to the value the board attach to form, and particularly to that part of it under water, emphasizing the great necessity there is for an increase to the bearing surface of the under-water portion of boats, and this end can, no doubt, be best attained by the putting into practice of the suggestions made by the principal ship surveyor for amending the rules and which aim at prolonging the form or fullness of dimension of the midship body under water well toward the ends of the boat. It is well known that by extending the body in this way greater buoyancy and stability are secured without materially affecting the speed. It is often supposed that defective stability due to bad form can be rectified by the disposition of the persons or things, but anyone with real experience of boats in a seaway can not fail to realize that this is the wrong principle to work on. Granted, therefore, that the question of form must take priority, how can it be best attained? And if we refer to Mr.
Archer's method of measurement, as stated in his amendment to the rules, it will be seen how simple and effective it is. For the purpose of illustration, we might take the model of a ship's boat obtained through the board's surveyors at Glasgow, the dimensions of which enlarged to scale represent a boat of L B D/30.0 8.5 3.5 and is an embodiment of the proportions amidships and at quarter distance from each end proposed by Mr. Archer.
It can not be too strongly urged that for a ship's lifeboat to be fit to carry the number of persons it measures for in any degree of safety, whenever it may be required at sea, the under-water or bearing surface should be carried out to the ends as much as possible and all straight lines avoided. The bows of many of the existing types of boat are examples of the worst possible form for safety, and the counters are as bad, if they can be said to have any.
_Depth._--It appears from the reports that the most generally approved ratio of depth to the breadth is 4/10. This has been established not only by our long experience, but by the numerous tests recently conducted by the board's surveyors at various ports, and the attention of the advisory committee might be drawn to this fact.
It is, of course, necessary also to have a good freeboard, but a well-proportioned boat does not require so much freeboard as the commoner type, as with proper sheer and under-water surface she is easy in a seaway. If the gunwale is too high, there is loss of power over the oars, which is serious when for the safety of the boat she is required to be kept head-on to sea, and with a fresh breeze, even in a good boat, this is not always an easy matter.
It is a matter for consideration that at the tests made by our surveyors the conditions were most favorable, being usually in smooth water of a sheltered dock, and, in not a few instances, considerable anxiety was felt for the safety of those on board when crowded in accordance to the existing rules. If it was thus in smooth water, one dare hardly contemplate the results in a seaway. If the shipowner does not see to it that a safe type of boat is provided, then the number of persons to be accommodated in boats which do not come up to the proportions deemed safe by the board of trade should be very considerably curtailed.
A. H. Y.
MARCH 23, 1912.
CONSTRUCTION OF SHIP'S BOATS.
It will, I think, be useful to consider the principal factors that govern the dimensions of boats forming part of the life-saving apparatus in merchant ships.
The minimum number and capacity of boats are determined by the regulations, and the capacity is determined by the product of the length, breadth, and depth of the boats. As the space on the ship in which to stow the boats is generally limited, it is generally found easier to increase their depth than the length or breadth, and this is further encouraged, I believe, by the cost of boats being quoted at so much per foot in length. The builder or owner determines the dimensions of the boat; the boatbuilder is concerned merely with the construction and, in most cases, usually their form or lines.
Attention has been called by the mark lane surveyors to the form and proportions of the boats used in the Royal navy. The proportion of depth to breadth is greater than is apparent from the particulars given, as all boats larger than a 30-foot gig have 6-1/2-inch washboards above the gunwale, and even the gigs and many of the smaller boats have portable washboards. It must also be remembered that all the navy boats are square-sterned, except the whaleboat, and are designed with easy lines so as to make good sailers; no air cases are fitted, and the seats are kept very low. The boats are not provided simply as life-saving appliances; as a matter of fact, the life-saving equipment of a warship is extremely small. It is true that each type of boat is given a certain "life-saving capacity," which is ascertained by crowding in as many men as practicable with boat in still water and all equipment on board. This number agrees closely with that obtained by the board's rule L B D .6/8. These boats, moreover, have a much smaller freeboard than is considered desirable in the merchant navy; but the occupants are all under discipline and in charge of experienced seamen. In the mercantile marine it may, and often does, happen, that the boats are crowded with panic-stricken men, women, and children, and instances have occurred, I believe, wherein there has not been a single man in the boat who has ever handled an oar before. Having these points in view, I do not agree that the navy type of boat is the most suitable for our purpose.
The chief desiderata in a ship's boat as a life-saving appliance are, (1) to carry the maximum number of people without overcrowding; and with (2) a reasonable amount of stability and freeboard; (3) and without undue interference with the use of oars.
(1) Is almost wholly dependent on the length and breadth of the boat; provided (2) is satisfied; depth has very little influence on it. For example, take a boat 30 9 3.5, 567 cubic feet by our rule, as a section (D) or (E) boat it should carry 567/8 = 72 people; such a boat should allow 30 9 8/72 = 3 square feet of area per person at the gunwale, which should be ample if all sit in the bottom who can not find seating room on the side benches or thwarts.
(2) Stability and freeboard are dependent upon the boat's breadth, depth, and form. The element of length does not enter into it, and it would be most unreasonable to limit the ratio of length to breadth, as suggested from Liverpool, or to limit the depth to the cube root of the length, as proposed by one of the London surveyors. Mr. Gemmell gives particulars, M. 26,298, of four boats tested, which proved to have ample accommodation and stability for the complements allowed by the regulations; the ratio of depth to breadth varied from 0.41 to 0.45.
Capt. O'Sullivan also reported five boats which he tested with ratios of D to B, varying from 0.4 to 0.44, all except one being satisfactory, the exception being rather tender and overcrowded, due to poor lines. The freeboards of all these boats when loaded were, I think, sufficient.
The depth in no case exceeded 3.6, and only in one case did the ratio exceed 0.44.
The surveyors, Liverpool, tested a boat 3.75 deep and having a ratio of D/b = 0.41, which proved satisfactory.
Capt. Griffiths tested a boat 4.1 deep, having a ratio D/b = 0.455, which he considered to be unsafe with the full complement on board.
The consensus of opinion is that the depth should not exceed 3 feet 5 inches or 3 feet 6 inches, and the ratio of D/b should not exceed 0.44.
This, however, is not sufficient to guarantee sufficient seating and stability. Capt. Clarke tested a boat 24.4 6.55 2.45, which was very unsafe with the rule complement on board. The ratio D/b is only 0.38 in this case. It will be seen, however, that this craft has exceptionally fine lines and is evidently quite unsuited to carry the rule complement.
It is quite evident that the form of the boat must be taken into account.
The dimensions of boats vary so greatly that generally the boat builder builds his boats "to the eye," using only a midship mold; it follows that the forms of boats of the same dimensions will vary considerably and with different workmen. Something more is required than a limitation in the ratio of depth to breadth. It is desirable that the sheer should be ample, and the form not unduly fined away within the midship half length. From consideration of the particulars and lines of the boats mentioned in the surveyor's reports, I think a simple rule to regulate the form may be devised such as I will indicate later.
It is, I think, necessary to limit the depth as a factor for ascertaining the number to be accommodated. The increase of depth beyond a certain point, while unduly increasing the number of people that may be carried, increases proportionately the required air case capacity, to meet which the seats have to be raised with a corresponding increase in the height of the center of gravity and decrease in the stability and difficulty in rowing. A boat 3.6 deep would have the thwarts about 3 feet above the bottom, and any increase in this height makes it very difficult for any ordinary man to row when sitting down. In rough sea the men would have very little control over the oars if standing up. A further objection to the very deep boat is its small stability in the light condition. It is not, I believe, an unusual occurrence for such boats to capsize in rough weather, before the passengers or crew can be got into them, and I have myself seen such a boat capsize in dock with only two men in it; due to lumpy water and a stiff breeze catching it on the beam when coming out of the shelter afforded by the dock wall.
I do not think, however, any limit of depth should be imposed, except as a measure of capacity. Any rules that may be devised should be such as are of easy and ready application, and which will not bear harshly on the boats that have already been accepted. I therefore suggest that the present rules will sufficiently meet the case, with the following modification.
In no case should the depth to be used in general rule (2) exceed 3.6 feet and 45 per cent of the breadth. In all cases where the actual depth is 45 per cent of the breadth or less, the maximum number of persons, as ascertained by rule (3) should not be allowed unless the boat has been found capable of carrying that number by actual test in the water, or unless the boat has at least 1/2 inch of sheer per foot of length, and the half-girth amidships, measured outside the plank, from the side of the keel to the top of the gunwale, is at least 90 per cent of the sum of the depth and the half breadth, and the mean of the half girths as similarly measured at one quarter the boat's length from the stem and stern post are at least 80 per cent of the sum of the midship depth and half breadth.
The thwarts and side benches should be kept as low as practicable, and the bottom boards should be so fitted that the height of the thwarts above them will not exceed 2 feet 9 inches.
A. J. D.
JANUARY 27, 1912.
(Mr. A. J. Daniel, acting principal Ship Surveyor to the Board of Trade.)
It should be stated that the new committee on bulkheads mentioned in the paragraphs of this letter which deals with rule 12 has now been formed.
Subsequently Sir Walter Howell wrote and sent three letters to the Advisory Committee which were as follows:
BOARD OF TRADE, MARINE DEPARTMENT, 7 WHITEHALL GARDENS,
_London, S. W., April 20, 1912_.
SIR: With reference to previous correspondence between the department and your committee respecting the revision of the statutory rules for life-saving appliances on British ships, and particularly to the letter from this department of April 16, I am directed by the board of trade to state that as an entirely new situation has been created by the recent disaster to the steamship _Titanic_ they assume that the committee, in reconsidering the matter in connection with the suggestions already put before them by the board will have full regard to this new situation, and the facts of the disaster so far as ascertained.
As you are doubtless aware, suggestions have been made in the House of Commons and elsewhere to the effect that, in view of the loss of the _Titanic_, action should be taken by the board of trade in regard to certain questions other than those expressly dealt with in the life-saving appliances rules, e.g., in regard to (1) steamship routes in the North Atlantic; (2) the speed of steamers where there may be dangers to navigation; and (3) the provision and use of searchlights on large passenger steamers; and the board would be glad to know the committee's views in regard to these, and any other suggestions which may have come to their knowledge, intended to diminish the risk, or to mitigate the effects of accidents to passenger vessels at sea.
I am, etc.,
WALTER J. HOWELL.
The SECRETARY,
_Merchant Shipping Advisory Committee_.
BOARD OF TRADE, MARINE DEPARTMENT,
_7 Whitehall Gardens, London, S. W., April 24, 1912_.
SIR: With reference to previous correspondence between this department and your committee respecting the revision of the statutory rules for life-saving appliances on British ships, and particularly to the letter from this department of April 16, in which you were informed that the question of the proposed amendment of the rules so as to admit of decked lifeboats being stowed one above another or one under an open lifeboat, was under consideration, I am directed by the board of trade to state, for the information of your committee, that the board of trade will be glad if the committee will consider whether any, and if so what, amendments of the rules, and in particular of the rule of April 19, 1910, and the rule of June 14, 1911, are, in their opinion, desirable with the object of supplementing the boats immediately under davits by as much additional boat accommodation as is practicable, having regard to the new situation which has been created by the recent disaster to the steamship _Titanic_.
A plan illustrating the principle is being prepared so as to be in readiness for your committee by Friday.
I am, etc.,
WALTER J. HOWELL.