The New York herald., 1878-02-24
THE LECTURE SEASON.
PROFESSOR A. CAREY SMITH ON NAVAL ARCH
IrECrURE.


IrECrURE.
Mr.. A. Carey Smith delivered tho fourth lecture Of
his course Of six Naval Architecture" before tho
Sowanhaka Yacht Club last evening. at DcImonico's
There was a largo attendance Of members and yacht
owners Tho lecturer announced the subject for tho
evening to DO "Designins Vessels on Paper" Ho
said that the ordinary way Is TO make n model and
transfer the lines TO tho moulding floor and build the
vessel from tho lines No calculations are made, but
experience Is rolled upon to produce fast aud hand
somo vessel Some Of tho fastest vessels have been
made In this way but the generally prove TO
10 costly aud unsatisfactory. made successful
aftcr numerous aud costly alterations. Thus the
question naturally arisos, Can not produce boat
by some other system with the good qualities OF
existing boats, and per haps some improvements"
MODELS woop
II is well for the beginner to mako model OF WOOD
and in this way train tho oye or the delineaton
paper OF lines and forms necessary Tor designng
An outline OF this method Is rs ioliows:-Thc model
Is made OF pieces secured together, and when
aone akon apart and tho piece next the keel laid
down on paper, with the middle limo touching
q line drawn for the base OF the half-breadth
pan The outline Is then drawn with sharp pencil
which gives the drst water limo. The other pieces
are proceeded with In the way, taking care
hold each 2icco TO IA limo across The back of the
model perpendicular TO the water lines, to keep
cuch piece Ia It's place The model Is tncu screwed
together and having squared III the endS cf the
loadwater line to wnero the sheer plan is 10 be
put lay the model on It's back with tho
ioadwater line just at the lines squared up,
mud draw &he outline OF tho model. This gives
the sheer plan, ana then the water lines
and ordinates LAID out tor the calculations From
these iwo pans the body plan is prod uced and
calculations made. But suppose the elements found
agree with those OF well known boat? II
there 10 departure IRON the model at all, OF what
use is III As ask any questions about the
model come TO standstili and musL then depend
upon alterations suit tho case. IL is iar better TO
n
DESIGNING VESSELS on PAPER
Mr.. Smith then proceeded to show the method OF
designing vessel on paper. Having nrst decided
upon plan It Is requred to flud out how much DIS
will sink below her designed waterine and thu top
side cannot be utilized for stability because Is so
the vessel has attained her max mum stabil-
ity, and, as the room inside depends upon
important factor If table Of some good vessels Is
before u.s. II is found that the best have about thirty
seven per cent Of the solid block mat Is length on
tipied by greatest beam at water line, and this
duct multiplied by thirty.sevcn per cent This rule
applies 10 almost all good vessels with no transverse
hollow 10 the floor.
MIDsHiP SECTION.
1t Is next required tho midship section,
rather greatest transverse section and here thero
found great similarly in good vessels nearly all
pr between MS and Of tho paral.
telegram formed by the width at line and dcpth
Of same wing settled OH the OF tho section,
We want to know how far aft the centre Of length OF
very common distauce, and that distance Is marked
The plan being drawn TO the inside OF the plank and
must be remembered that as the square Of Ihe beam
with the plank of to the square OF the beam with
the plank is the area with the plank of to tho
the section and decids upon the height out
Of water; boat should be able to koel
1fteen degrees bclorc the deck reaches the
water The sheer is next drawn About twice
the height at the lowest place makes good height los
mo bow and the M stern mus be made nigh enough TO
load water line and next 1t Is wunLed to know how
drag neediul About twice the draught forward
Is proportion Tor ait Ordinates are now laid out
for calculating the centre OF lateral resistance, which
should be very short distance forward OF tho greatest
drawn in and the outline OF sheer plan Is obtained
LOAD WATER LINE.
Tho load water liue then demands attention, and
this the shape OF the boat abovn and below
line great must be taken with 1t. Tho bost
way Is to take known good water limo and divide the
forward partthat from the widest point the end
OF the water line ~ the stcrn-by tn's uonc di.
vide each ordinate by the widest one, which gives
ending IN o. Then take the forward part
OF our proposed water line and divido II
beginning with No. i by the corresponding figure
taken from the column above, whcn Will gye q iinc
alter end OF the water line hen dealt with. sec.
ton line laid out midway between tho greatest
beams and cenlre line in the breadth plan; mark
where the line cuts the section in the body plan aud
trunsfer II TO its place in the sheer plan Having de-
ternined the width and shape OF tho sterh-remepl-
bering the after body should be just the shape
OF the greatest transverse section, but diminished
trunscr tho point whore Inc section line cuts the
stern 10 The body plan 20 The sheer plan, and pen
batten with weights and get II to a fair curve from
transverse section; this will como little hol-
low as u crosses the load lne square down
point where the section line crosses the water line IN
sheer plan TO al;-Dreadth plan, and then point 10
secured to sweep the loadwuer line BY. Pen batten
from the greatest transverse section end OF
lDe touching tho point just squared down make II iar
and the inter end OF The load water line is obtained
The ordinates from the sheer plan are continued 10
calculate The area OF the load water line, simpsons
rule applied to get the areaths should be between
sxty-two cent and seventy per OF the paral
Telegram formed by the length and breadth OF load
water line. II tnis Is approximaed tho cross Sec
the forward part is wanted nearly as sharp us The LOAD
water ine or narcd bow will be The result
INCLINED LINES.
The width at keel and depth same, load water
line and deck breadth 10 80 by are now had; then
the rest Of the frames sre put IN; but II must bc
membcred that the ancrsbody should DO the
form OF The greatest transverse possible anu that
ali the frames be iair curves Now ding
onal Is put IN midway between tho section line
ana the bige and as ncar square with the
face OF the frames as possible Ihis line Is pro-
iected ON the sheer pIan-that is the diagonal
distance measured and laid down pondng
frame, using toe lowest wafer line base ne The
ending OF tnis line where the diagonal touches the
stem at the rabbet squared down TO the tase line,
the diagonal distance at the stem IN rks the width;
the same method used ait. This line shows the
frames air, ami II The curve does touch all OF
them they must be made to suit the diagonal, though
NO change OF the iibc ut the water line or greatest
OF ali the water water h"es @ and % % pro,cc. them in IN
1he nalf breadth plan and put in some
uiAgonals at the most abrupt curves VI the frames
Now lay dow1 an inclined water limo OF ten degrees
and measure where II cuts The frames on the inclined
line project II on tho halt breadth plan. his limo
should DO very similar TO the load water line nil tho
care taken goes Tor nothing ms it Is plain that II tho
load water line Is right when the boat upright and
moving with slow motion the line should be equally
good when urged TO high speed: IN every case
where the inclined line Is bad the boat fails at high
rates Of speed. fia Us
For Instance, when the Dnuntess beat the Rceolute
In the race to Cape May and back 1t mainly due
10 tho bad inclined line oil the latter. those
bonrd said the forced the rail- ana, oil
course In this case NO great speed could be made.
The old idea about straig side line and long floor
Is completely demolished by facts Tue Comet has
beautiful inclined line aud also las Tho round
est side oil any yacht IN tho club, and
We have yet TO Sec greater speed with
a beam wind; her deck Is nearly sharp as the
water ne Tno sappho IL unequullcd In this respect
and in evcry case the shape VI the inclined line COIN
cidcs with tho speed. This line cannot bc shown In
q models not shown at any rate, though IL Is one
OF the important lines a boat, and unless Il