New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1899-09-25
A SAILING TORPEDO BOAT.
THORNEYCROFTs SKILL EMBODIED IN
THE SHAMROCK.
THE LEAD 4 FALSE KEEL 1NDEPENpf'N
OF THE WATrRTIGHT HULL III
FIN USEFUL FOR WATER
BALLAST

FIN USEFUL. FOR WATER
ballast
After all tho guesses about the Sham'''N
struction tho correct facts have 1T last p''h '"-
tanned one or two things have already oeel N''N'
vl.h reasonable certainty-for instance that '''
boat was chiefly built Of steel. aluminium ""u
hron7o Royond this little has been pubhShe' ~
~ tho interior that has not been open 20 inc S"s
rcion Of being plausible guesswork- ana me '',-
lowing paragraphs may show no" m"'" N"'SS' '1',
WIS printed. aud viii also sho" mat '''ouR''
bar construction the celebrated Thorn"N'r"''S nav
utilized their host methods FOR producing 'h'"
lichtest and most wonderful torpedo boats SO ''''
n NAV be said with fair correctness that tho Snam-
rock is A Thornoycroft torpedo boat under san.
HOW THE SKELETON rs MADE.
Tho frames ~ the vessel are 81 special form OF
stool angle s'ifened on ono fang" So as 10 CIV "
ono construction tho advantage OF tho We" kh'"'
"anelo and reverse angle" although "ino"' ~"
rf,o,i,q necessary I'm ordinary circumstances.
These frames are rolled from a description "' ~''
which has great strength and stiffness ana H''
nossoseos considerable ductinty Su'N P"''l''8 "''
rof easily combined. and q has only boon aIi"r
,,h labor and research that tho allows needed for
Tho rnrnoqo have boon discovered and the metal
rroducod for torpedo boat work. The process 20
secret NJ the Thorneycrofts the method NOT having
been patented.
Tho frames are spaced AZ tNeny-nine Inches on
centres 80 that the veesc rs not likely 90 suffer
from weakness ~ framing or show hollo"s between
her ribs NJ very lightly plated vessels do ar times
10 secure those ribs together and give fore and af
strength there arc four longiWdinals or siring"ff
n, bulb ankle stoel worked inside the frames ana
attached 70 them by lugs rlveted The deck
hoan,s are special torpedo boat steel anglo bulbs
and they arc attached 70 the frames hy gussei
pieces again In torpedo hoai fashion. The aerK
baan,s ara further connected with the Sides NJ the
hull by means of row of stool tubular pillars Oh
each side. These 20 from the upper big" strinlcT
70 a longitudinal under the deck beams lner" IS
also a cAutral row ~ pillars extending from mo
deck proper 10 the thwarship angles-or reverse
angles-whch form the cabin sole Tho stem an"
stern post arc bronze castings. and tine rulder
which IS OF large area. IS also bronze casting
The whole ~ the framework is so hraoed and tied
that II affords an exceptionally rigid structure IN
dopondently OF tho plating which Of course adds 10
the strength.
HOW THE FIN KEEL IS BUILT
In speaking Of the fin keel It NAV he said that
the cross section 81 the Shamrock and other modern
Yachts resembles the section OF modern cham
paTne glass with tho foot or stand removed There
e IN both cases shallow bodied vessel from which
depends a long projection. the pendant part oei"t
hollow In the Shamrock the frames ar" nent round
70 form the sides and continuous from the
dock 70 the bottom Of the fin: and It may be here
said that tho bending Of these steel frames 10 such
unusual curves and reverse curves has been 4 some"
what difficult piece OF work, which. however mas
been beautifully carried out There is Just room
for
sides being about eighteen inches apart though
,bo width varies the narroHest part being near
Wi ore tho I'm olrs the main body. II VIII no un-
derstood that I'm d fore and at direction the I'm
only extends under about u third o. ihe vessel 8
length there being the extensive oyerhang charac-
tcrIstlc OF the modern yacht. The bottom OF the
I'm "a Mated off square, and TO this the single
massive lead casting OF eighty tons Is secureF
bolted by gun metal or bronze bolts IRON or steeI
being iradnissibe account OF the galvanic acuon
that would he SGT up.
The bottom OF the Nm IS its widest part ana y
~. ba EXPLAINED that tho lead IL false keel
rorerlv so called az the vessel is complete
watertight structure in virtue OF It's plating ana
v.ifboi, dependence Oh the lead. The leaa keel IS
eooic,rc,,lar or approximately in cross section
~ the bottom The Columbia's lead IS or re'tant"-
lar section. and the centre OF gravity o. '"e i'"1 .
thus lowered.
THE Fin MUST LIFT SO TONS.
Steel plates which might he described bulk
hoods ara carried down inside the fin. thus hracing
the TWO sides together. construction such AZ
this has 10 be very carefully considered, for II has
70 bear the stress OF the opposing forces due 10
the pressure Of the wind on the sails and the enor
Of the lead TO keep the vessel upright A. an in
clinaton OF forty-ilve degrees the bending moment
Of the fin near its junction with tho main body
OF the vessel would be about coo foot tons.
An English writer has lately called attention 70
the fact that this fin might he used for carrying
leaking or taking water board FOR any other
reason. the water would naturally find It's way into
the hollow fin keel that being the lowest part. This
nicht result IN the addition OF 10 fifteen tons ot
water ballast and though water IS very Ineffective
for ballastng. AZ compared to lead yet it would
make very useful auxiliary y q had not 10 be
maid FOR in the measurement. The long overhang
and tho sloping ends. forming an acute angle with
the water, make every inch OF immersion or great
Importance in regard to the water line length and
when r. IS remembered that fourteen tons of water
IN craft like the Shamrock or the Columbia
would make a difference Of four inches I'm the i'm
mersion Il will be that the factor Is not al
together without importance Naturally In the
older form Of vessel tho skipper always dd his
best to keep his craft free from water. which would
run down into the lee bige and act I'm the opposite
way 10 ballast. hut confined in the I'm keel n
would remain in tho middle Of the boat As IN
tmated these considerations have no bearing in re-
gard the forthcoming race with vessels so
stanchly built as the Shamrock and the Columbia.
Moreover the respective competitors will see that
no unexpected advantage Is obtained
HOW PLATED AND DECKED
Tho skin plating below the water plane ~ on
tirely Of manganese bronze well known copper
alloy. which Is strong as steel and possesses
the advantage Of taking high polish and in this
way friction between the water and the vessel
is brought to a low point This IS we'll known.
is an important factor IN the design 81 a racing
Yacht. The plating above the water line IS of
aluminium. alleged in such way t. give add
tional strength without. Il IL asserted materially
Increasing the specific gravity. what ls the nature
II the alloy e Kept secret but Il said that the
tensile strength Of 1t j. fourteen tons n square