The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1844-10-22 00:00:00

SUIPBUILDING.

. TO THE EDITOR OF THE LIVERPOOL STANDARD.
SlR,—Seeing your town is the principal mart of our na-
tional commerce throughout the world, permit me, as oc-
casion may present, to solicit a corner in your useful pa-
per, in diffusing some general remarks on the principles
of shipbuilding, thereby to create an inquiry as to the de-
fective nature, both in theory and practice, of our com-
mercial navy. Nothing but being a %ell-wisher to the
prosperity of my country could induce me to this task,
seeing I shall have to ccntend against a hydra of many
beads.
In this our day of extensive improvement in all branches
of art and mechanism, it would be natural in concluding
that shipbuilding, as first in extent and equal in import-
ance to any other branch of science, would he first in a-
vance ; t.ut it is unfortunate for this country, that realities
in improvement too frequently produce counterfeits,' and
there never was a day in which spurious systems and er-
roneous theories have more prevailed, and in no branch
bave they taken such a deep bold, or been attended with
such direful consequences, as in that of shipuilding.
Many visionaries have started up who, bp fallacious argu-
ments and specious reasonings, have introduced false
principles and innovations into this otherwise receding
art, and none more so than by that less than futile, that
ruinous opinion of supposing that an artificial floating
body, acted on by different elements, should have its
form regulated by that of a living animal ; and the only
reason assigned is that a fish sports in its own element
with ease and rapidity. If this reasoning is of force suffi-
cient to establish a principle, in opposition to nature's

laws, on the same parity of reasoning the form of a bird
may answer as well, yea better, from is greater simi!arity
to the winds acting, and rapidity of flight. Then let me
ask those men who have drawn so many to their opinion.
the reasons on which those deAructive principles are by
them established? Natnralists inform us that fishes, like
birds, perform their functions of speed through an inflat-
ing instinct acting on animal nature, under the guidance
of a superior power, the machinery of which is far beyond
human ken ; whereas a ship being an artificial body, sup-
ported by the density of an element inimical, and to which
it cannot be reconciled—an element always in motion to
relieve it from its inanimate and pondoreus burthen—
which inanimate mass is propelled through the obstruction
of another element acting on expanded canvass, and that
at a considerable distance from the point of action, or the
vessel's displacement; Why, then, will men fetch their
opinions from such discordant incongruities, when corn
mon observation, and a few prac ical experiments, would.
make them wiser? Tile neglect of these necessary re-
searches blinds them to the true principles of floating
bodies. _

The first maxim with wise and judicious men is to im-
prove on the works of others, or by drawing solid infor.
mation from the experience of practical men, ever an ad-
vocate for system, yet this at times must give way to na-
tural or practical genius; for it is an established fact, that
our best formed merchant vessels, qualified for every pur-
pose—vessels that sit on the wa'er, light or load, as if in
their own element; possessing the seaman's confidence as
to their safety under every circumstance, are built by men
of practical knowledge, whose only science is a common
understanding to discern betwren a good or a bad quality,
and apply them with truth to the best advantage,—who in
theory cannot give a why or a wherefore as a cause that
their vessels excel. In this one thing they are cinlident,
which is, that the only place for a ship's cargo is round
the centre of her capacity; and experience has taught
them that this point should ever-be at or near her half-
length, which ahne can relieve the vessel from hbouring
or straining in a sea. Having thus briefly shown that the
natural position for the main transverse section (dead flat)
should be at or near the vessel's half-lenttli, it remains
for me in my next to demonstrate its principles, seeing it
would occupy too much of your columns for one inser-
tion. I shall therefore conclude by giving some useful
information. First, a very easy method whereby may be
known the safety-weight that may be put into any vessel,
whatever may be her form. Take the length of the keel.
as by the old meas'uternent, front whit,h deduct three-
fifths of the main breadth, which sum multiply by the ex-
treme breadth ; then tike the depth of the hold at the side
of the keelson, to the under side of the deck in mid-
ships at the fore pint of the main hatch, deducting from
the throat of the floor the thickness of the ceiling; also
take the distance front the middle line at the lower part of
the deck, to the roundest part of the bulge, allowing only
the thickness of the ceiling ; add these two depths toge-
ther, the half of which becomes the multiplier as the
depth in the hold ; the whole sum divided by 94 will show
the vessel's burthen in tons.

In my last some observations were made as to the breadth
of vessels, and as something like a standard may be of use
to young men entering on ship-drawing, a scale for breadth,
depth, draught of water, end length and height of wing
transom, may be acceptable. Take a piece of cartridge
paper, 42 inches in length by 10 inches wide, at one iech
from the lower edge; run in pencil a line 36 inches in
length, as a base line ; below this run in two others, a quar-
ter of an inch apart ; divide the space between the base
line and first, into quarters of inches, being 144 parts or
feet ; run up through the paper perpendiculars at every
fifth quarter, as 5. 10. 5, 20, Ike.; set up on the perpendi-
cular at 45, from the base line 51 as the half-length of the
wing transom, also 94 as the draught of water from the
rabbet of the keel, 10/ the height of the wing transom, 12
as the depth from the rabbet of the keel to the plansheer,
and 16 as the main breadth, viz. 45 feet the vessel's
length at her load line, 51 feet the half-length of the wing
transom. 94 feet as draught of water at the stern post from
the rabbet of the keel, 10; fee t the height of the wing
transom from the rabbet, 12 feet as the depth iu midship
front the rabbet of the keel to the plansheer, and 16 feet
as the extreme breadth. Also, set up on the perpendicu-
lar of 144, as the half-I,ngth of the wing transome 11 feet,
18.1 feet as the draught of water at the rabbet of the stern
post, 211 feet as the height of the wing transom, 21/ feet
as the depth in midships from the rabbet of the keel to the
gunwale, and 324 feet as the extreme breadth ; through
their correspondent spots, from 45 to 144, run straight
lines, which will give the necessary information at any
given length on Coe scale, being cal-ulated for every ves-
sel, small and large, to set by the stern one foot. Exam-
ple : suppose a vessel about to be built of about 285 tons
old measurement, the nearest length at het load line would
be 102 feet; run up on your scale at this length a perpen-
dicular, when it will show, 9 feet for the half-length of the
wing transom, 14/ feet from the rabbet of the keel at the
stern post as the draught of water, giving at the stem 13/
feet, 16 feet 8 inches as the height of the wing transom,
and 19 feet its the depth from the rabbet of the keel to the
gunwale in midships, thus showing a scale embracing all
those properties front a 50 ton vessel to a ship of 700 tons ;
and if necessary the scale may be extended to any size
ship.—l am, sir, &c.
JOHN COCK.
Pembroke Dock, 12th Oct. 1844.