EXPLANATION OF THE PLATES.
473
D, The new line of post, with the rake taken out and brought perpendicular to the
new line of keel, B.
E. The stem to have a flare or flam to correspond with the bow.
To prevent rolling as much as possible and falling to leeward, two deep bilge
keels to be fastened to the bottom plank, with bolts clinched on the inside. (These
keels have been well tested in certain vessels belonging to the Honourable East India
Company, in Bengal.)
The fore and after bodies of the American schooners (applied as just described)
have been proved to be the best suited for velocity, the sharp flaming bow dividing
the fluid with the greatest facility, and the fineness of the run allowing it to pass to
the stern with the utmost rapidity.
This improved form is obtained by giving a great proportion of length to breadth,
which has been so successfully adopted in the construction of all recently con
structed steamers (particularly those built by private companies or individuals).
It is recorded in the translation of Chapman’s celebrated work by Dr. Inman:
“ Care must be taken to shape the fore and after bodies, the former so that the
fluid may be cloven with facility, and at the same time the displaced fluid dis
persed and transmitted towards the stern with as much ease as possible.” Velocity
in steam vessels is, therefore, obtained by a light draught of water, and keeping the
fore and after bodies sharp, and giving the least proportion of length to breadth with
reference to the required stability, viz. for sea-going steamers, six times the breadth
for the length at the load water line ; in vessels for inland or river navigation, the
length has been carried to ten times the breadth in some of the American boats. Vide
Stephenson’s late work on American Engineering.
PLATE XCVII.
DRAUGHT OF THE FORBES STEAMER, CONSTRUCTED AT CALCUTTA,
BY ALEXANDER HENDERSON, ESQ.; CHINESE RIGGED.
This plate presents a sketch of the masts and sails of the steamer Forbes, as fitted
when she towed a ship of 380 tons from Bengal to China against the monsoon in 1830,
with the fore-sail and main-sail; the plan of the Chinese sail was adopted as best suited to
the purposes of a steamer, giving the greatest spread of canvas, with the least weight
of mast and rigging ; the stretchers or yards in the body of the sail, by dividing the
strain on the mast, are useful to reduce the weight aloft and require little rigging;
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