The sun. [volume] (New York [N.Y.]) 1833-1916, 1900-12-02
V EXPERIMENT TANK.
sTRfNIS0 RFsrITs IROW rms HODEL
BtSfN ~ WAsHJN0TON.
N Experiment win Models for the Fivs nat
tI.ships ~ the Geor Eia sisss. Ia cost Abons
$50 moo 00O. shove How 1000 Horse
Power lnnId Ne aa.ed for Zach Ne.srl.

~
rent annual meeting Of the Soclct' ~ Naval
Architects md Mrrn" Engineers WAS read -
Naval tun-triotof u " lor on Tho I ni'ed
states tXperiirertal Model BASIN" nj the Wash
iust"n \nvy Yard This experimental basin
3. simply u tank where models for varships NAV
ho tested ohi"n, 10 Obtain speed cnrahillti'~.
n has been iu operation for ahuutR ,enr and "
i. ltohlbl, the most complete ~ tho Kind In me
world \ lot " agitation vPs required 10 get
congress iu nuthorIe II Rotor" II was CONF
l"t"d the navy used some patchwork sub
-titut"s Tor such experiments. All di-"us ~
~ 10 M" models 81 yr,sols authorized VS.
irICnoallr speculative and not until ia" i1
+ ned -hi'~ had made their trial runs could any
satisfactory data be secured about them ~
course u was then too late t." remedy aHy fau' :
that might exist In the ships.
The great value Of such an experimental tank
ha- been shown recently In making tests Tor the
20 models for the five great battlcships 81 the
Georgia class which have been authorized.
Thoso arc the most powerful battleships ever
constructed In this country. and, as Mr.. TAYLOR
sa' s., ar" mot surpassed In size by any vessels
a'Oat or under construction" IL was very I'M
portant. Therefore. in hattleship economy 70
select the model which would give not only the
greatest speed that being one Of the primary
requirements Of that grade OF vessel hut also
''N '''' 'AaAe NhhN fN'' "'F' '''' '"N
Last engine effort. The displacement being
smaller less amor would b. necessary and a
more powerful arrangement 81 fighting quail
t!er could he made.
Two models. Georgia No. / and Georgia No.
4, were cxperimentcd with. Model No 4 was
longer than model No / and represented a
Vss Loo 5lot tons morcd isrlacenient. Thofgurss
Of the vessels rrpr sented we're Model No.
/ l"uc'h. AZ feet bear. u feet draught. PAS
fect. displacement. ii.lsO tons. Model No =
length, 43j feet: beam. rs feet draught. 23.5 feet
displacement. li.6pO tons. 1t Wa found that
tho larger ship, being fifteen feet longer and $40
tons heavier. would reach a speed OF nineteen
knot' with 1900 less horre power than tho
smaller vessel. in other words. Il would re-
qu.re 1900 horse power 20 drive n Georgia
built on model No. l at a speed Of nineteen lnots,
while onl, 1900 horse power would be required
TO drive a vessel built on model No 4 at nine
teen knots. Needles to say model No. 4 was
selected at once for the vessels OF the Georgia
class.
This decision viii mean a tremendous saving
Of coal during the entire lives OF the vessels Of
that class. Although the Georgia and her ste
tiers will present fifteen more feet OF target 70
an enein} and although n greater weight Of ar
NOR for the percentage Of protected area may
be required the great increase in cruising
| uhNAHA A'ls " Wv dNl'Al VI "a l'of''
will lie an enormous gain. The saving involved
In tho experiments for the Georgia class Of bat
lie h p- alone Is worth all the money and trouble
t.i' ~ cost 10 get the experlu ental tank.
The experiment with the Georgia models
also emphasized the conclusion which had
been reached with nine models OF the York.
town class OF gunboats. namely. that length
and displacement OF a vessel are the chief fac
tors involved in resistance. In other words.
the speed OF a vessel depends most upon the
length and displacement, and changes In shape.
beam or draught make very little difference
IN this respect. II Is the length and tonnage
that count In driving a chip through the water.
Nine models. each rcrr, seut.rg a ,ess | $50
feet long. With a tonnage Of l.eso. which arc
tie !eugr h and tonnage OF the Yorktown, were
tried. These rcpres ~ tod v ssel that varied In
beam from "a feet in model No. l TO IS feet in
model No. s, increasing three feet In each
model tried. They varied in draught from
81 feet In the V 81 rHpr 'nted ty IN" frst
moielto a draug ht Of lo.5 feet in a gradually de-
scending scale. No such variation In tho ratio
Of beam to draIght would occur IN practice
The curves plotted on the cards showed prac-
tically the same resistance for all the models.
In the shallow models, however. there was
practically no Interference between the bow
and stern wave systems. proving that It Is
tAf lux iAI ~ O'hN NiN a h''P NAH'At Nv
that produces the greatest wave disturbance
In motion.
These experiments with the yorktown and
Georgia models are strongly confrmatory
OF the theory, we'll known In shipbuilding :.
that speed may DO gained by increased length.
but thsre is no known way Of determining
how much length shall be given TO a vessel
70 secure a certain addition Of speed with the
same engine power and displacement. unless
model experiments are made. All this has
a most important bearing upopth- design
for our attleships, Because Of the shallow
conditions OF soma OF our harbors IL IL necessary
70 give our battlsshipS fuller forms and shall
lower d~raughIs than foreign battleships Of
the same displacement have. II is somewhat
harder 70 drive a shallow ship than a deeper
one Of the same displacement, and hence comes
the mscb im ~ IaSst6d iSG 4 Sa, IL fHSi n oTd sqs 10 m nGs
M the speed lost by having a shauower, do
sign. The, cost Of the i've battleships ofthe
md. the ratio Of length 20 horse power being
%o5taired hy ~"Ni"rinent, a great gain ~ made
these most expensive vessels.
OF course tho best wav to bring an expert
mont ! tank 70 its fullest state of efficiency
would he 20 experiment with models OF ships
to tS' n-6dnce data hat world he known as con-
stants that ia. so "a To produce fixed rules as
Of vessel, at given rt'.' ~ spest. quite y
Wv NN-'NlA''h Hh,'' 80, - -
with the models for new ships
has Interrupted that work. Data %ob'atnad from
eVpaimont basins Of foreign nail0ns wore
used where such were lacking In Washington
md the evnoriments with now design we're
therefore oarried on ~ n satisfactory conclusion
M Indication Of the sccuracv 81 the model
eycer'r.orte rrny he ~ tnired In The Comnart-
sor Il tho sUee : o. taired IN the tank md those
obtained IN actual rerfornance Of certain bat
tloships Tho Fuaed ~ tho OREGON class, 9ts
feet lon~. on trinl vas 10 q knots Tie GORE
syonding speed ~ n ?O-foot model In the tank
vas O9 nots Tho 81 cod ~ the Iowa class,
sco feet long, on trial wns II / krots. The spo"d
Of tho Iowa '"odcl In tho tnnk Wns OF nots.
The e. God 81 tho kertuckv class, 9es feet long.
In actual trial was III knots The nodeTs
srecd was 100 knots The estimated speed
of tho Maine class. $50 feat long. Is IL knots.
1fe sreed ~ the model for this class showed
n speed ~ 400 knots r . estimate speed 81
the GEORGIA class. as feet lolg, ls. ~ knots,
and the e~vperiwents with the model showed a
sncod n ~ knots
The eXperlmertal tank In. Washington IL In
a building 600 feet long and ~ feet 2 irchea
Wild" Tho hasin itself Is 40 foot long nd a. feet
3 inches ide. Tho main section 81 the tank
Is II foot G inches doep. II hclds about 900
NnO "pll0ns of water The water IL taken from
the Citv supply ~ Washington In the Potomac
River, several - ilos above tho ctv In order
20 secure thoroughly accurate data tie " alter
must lN Ia 81 lilo condition for all tho eyt sri-