Please see the accompanying incidental table showing how this number of boats can provide for the three­quarters additional capacity also, if of about 500 cubic feet per boat to 600 cubic feet. A.H.Y.
__________________
Table of incidence (informative)
Gross Tons Number Cubic Cubic Total Equivalent boats
of boats feet feet cubic At 500 At 600
add'l feet at cubic feet. cubic feet.
1 3/4.
10,000 and under 12,000 16 5,500 4,125 9,625 19 16
12,000 and under 15,000 18 5,800 4,350 10,150 20 16
15,000 and under 20,000 20 6,100 4,575 10,675 21 18
20,000 and under 25,000 22 6,400 4,800 11,200 22 19
25,000 and under 30,000 24 6,700 5,025 11,725 24 20
30,000 and under 35,000 24 7,000 5,250 12,250 24 20
35,000 and under 40,000 24 7,300 5,475 12,775 25 21
40,000 and under 45,000 24 7,600 5,700 13,300 26 22
45,000 and under 50,000 26 7,900 5,925 13,825 27 23
50,000 and upward 26 8,200 6,150 14,350 28 24
One­fourth of the above boats may be carried inboard, but they should not exceed 500 cubic feet in capacity, so that they may be readily drawn up to the davits. A.H.Y.
March 30, 1912.
__________
DRAFT AMENDMENT OF GENERAL RULES.
(1) Boats.All boats shall be constructed and properly equipped as provided by these rules, and shall be of such form and proportions that they shall have sufficient freeboard, and ample stability in a seaway, when loaded with their full complement of persons and equipment.
All thwart and side seats must be fitted as low in the boat as practicable, and bottom boards must be fitted so that the thwarts shall not be more than 2 feet 9 inches above them.
All boats and other life­saving appliances are to be kept ready for use to the satisfaction of the board of trade. Internal buoyancy apparatus may be constructed of wood, or of copper or yellow metal of not less than 18 ounces to the superficial foot, or of other durable material.
SECTION (A). A boat of this section shall be a lifeboat of whaleboat form, properly constructed of wood or metal, having for every 10 cubic feet of her capacity, computed as in rule (2), at least 1 cubic foot of strong and serviceable inclosed air­tight compartments, so constructed that water cannot find its way into them. In the case of metal boats an addition will have to be made to the cubic capacity of the air­tight compartments so as to give them buoyancy equal to that of the wooden boat.
SEC. (B). A boat of this section shall be a lifeboat of whaleboat form, properly constructed of wood or metal, having inside and outside buoyancy apparatus together equal in efficiency to the buoyancy apparatus provided for a boat of section (A). At least one­half of the buoyancy apparatus must be attached to the outside of the boat.
SEC. (C). A boat of this section shall be a lifeboat, properly constructed of wood or metal, having some buoyancy apparatus attached to the inside and (or) outside of the boat, equal in efficiency to one­half of the buoyancy apparatus provided for a boat of section (A) or section (B). At least one­half of the buoyancy apparatus must be attached to the outside of the boat.
SEC. (D). A boat of this section shall be a properly constructed boat of wood or metal.
SEC. (E). A boat of this section shall be a boat of approved construction, form, and material, and may be collapsible.
(2) Cubic capacity. ­ The cubic capacity of an open boat and of a deck boat of section (D) or section (E) shall be ascertained by multiplying the product of the length, breadth, and depth by 6, subject, however, to the following provisions:
The length shall be measured from the foreside of the rabbet on the stem to the afterside of the rabbet on the sternpost, and the breadth shall be measured from the outside of plank to the outside of plank amidships. The actual depth shall be measured from the top of the gunwale to the top of the bottom plank next to the keel, but the depth used in calculating the cubic capacity shall not in any case exceed 3.6 feet; and if the actual depth measured is equal to or less than 3.6 feet, the depth used in calculating the cubic capacity shall not exceed 45 per cent of the breadth measured, as indicated above.
If the oars are pulled in rowlocks, the bottom of the rowlock is to be considered as the gunwale in measuring the depth of the boat.
If any question is raised requiring absolute accuracy, the cubic capacity of a boat shall be ascertained by Stirling's rule, subject to the foregoing provisions as to depth.
(3) Number of persons for boats. ­ (A) Subject to the provisions of paragraphs (b), (c) and (d) of this clause the number of persons an (see rule of June 14, 1911.) open boat of section (A) shall be deemed fit to carry shall be the number of cubic feet ascertained as in rule (2) divided by 10, and the number of persons an open boat of section (B) or section (C), or an open or decked boat of section (D) or section (E) shall be deemed fit to carry shall be the number of cubic feet ascertained as in rule (2) divided by 8. The space in the boat shall be sufficient for the seating of the persons1 carried in it and for the proper use of the oars.
(B) An open boat of section (A) or section (B) or section (C) or section (D) or section (E) shall not be deemed to be fit to carry the number of persons ascertained as in paragraph (A) of this clause unless the boat is so constructed that it has a mean sheer of at least half an inch for each foot of its length and that the boat's half­girth amidships measured outside the planking from the side of the keel to the top of the gunwale is at least equal to nine­tenths of the sum of the boat's depth inside and half its maximum breadth amidships, and that the mean of the half­girths measured in the same manner at two points, one­quarter of the length of the boat from the stem and sternpost, respectively, is at least equal to eight­tenths of the sum of the depth inside and half the maximum breadth amidships.
(C) A decked boat of section (D) or section (E) shall not be deemed to be fit to carry the number of persons ascertained as in paragraph (A) of this clause, unless the top of the deck amidships is at a height above the water approved by the board of trade, when the boat is so loaded.
(D) If the surveyor is doubtful as to the number of persons any open or decked boat is fit to carry, he may require the boat to be tested afloat with the intended number of persons on board.
(E) The rules numbers 1, 2, and 3, as now amended, are not to be retrospective and are to apply only to boats built after.
SHIP'S BOATS.
The salient feature of the reports of the board's officers on this subject is the consensus of opinion that the form of a boat is the chief factor to be considered in determining its value as a life­saving appliance.
It has been found that while there are many boats of good form supplied to ships, there is yet a large proportion where the boats are not only not so good, but which can only be regarded as unsafe if they had on board anything approaching the number of persons for which they measure.
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 shipbuilder, 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 boat builder at a loss; (3) the aim of the competing boat builder, 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., LXBXDX.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 boat builder 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 life­saving 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 under­water 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 cannot 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 Glasglow, the dimensions of which enlarged to scale represent a boat of L B D/30.0x8.5x3.5 and is an embodiment of the proportions amidships and at quarter distance from each end proposed by Mr. Archer.
It cannot 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 under­water 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 well­proportioned boat does not require so much freeboard as the commoner type, as with proper sheer and under­water 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 head­on 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 life­saving 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 boat builder is concerned merely with the construction and, in most cases, usually their form or lines.
