The sun. [volume] (New York [N.Y.]) 1833-1916, 1897-10-29
THE DRY DOCKS.
view Structures OF Concrete ana Concrete m
frances for Ola DocL,.

" ~
frances for Ola Dock,.
From various sources in tho navy como calls
for additional dry docks; and although the rec
concentrations on tho subject are not identical,
yet the differences are less remarkable than
tho points of agreement, while these latter are
30 urgent that Congress may fairly be expected
to give heed to them.
Rear Admiral Matthews, Chief OF the Bureau
of Yards and Docks, asks for four new docks,
three of them to be built OF concrete, at Boston,
Norfolk and Mare Island, and the fourth, a steel
floating structure for Cuff use, TO be placed at
Key West, Tortugas or Algicrs. He advises
that no more wooden docks be constructed.
The recommendations of tho naval Board
specially appointed to consider this subject
asked, as will be remembered. for still moro
new docks. but Rear Admiral Matthews prob.
ably calls for as many US will be authorized ut
the coming session. There Is one recommends
tion'0f the board. however, which seems specially
worthy of attention. namely, that of fitting with
concrete entrances the five timber docks we al
ready have on tho Atlantic coast, namely, two
at New York and one each at League Island,
Norfolk and Port Royal. This project can
obviously bc connected with the enlargement
of such docks. Tho plan contcmplatos the
gradual transformation Of the docks into solid
concrete structures, but a beginning is 10 bo
U1ulC IL IL tllThnCtS, DtCtuSt ~ lINob
serious troubles OF timber docks are likely TO
occur. II the entrances are all right, 1t Is an
eAsier matter TO get at and repair other parts;
but sub-surface re pairs at the entrance require
the building of a Golfer dam for that express pur-
p,ss, and this is a very heavy expense, as Is
shown in the current case OF the Brooklyn dock;
A permanent caisson entrance avoids this and
is useful also for all other repairs.
With regard to the much .mOoted question OF
wooden versus. concrete docks, tho boards
view a, Il II thI 'bo 1t iipi Il only Toc z question ns,nsa OF NH Iim9 9n DO,
reurhpi such n stupp ma IN he unfit for use. en-
dangering ships in Them from their liability to
| sudden inRrcss of water from collapse Of their
All the wooden docks examined, It says, show
deterioration of the material, due to its per-
ishRble nature, and, in instances, weakness due
to the lack of secure fastenings OF the %tinbers.,"
The most rapid deterioration Is at Port Royal.
the %Srfo Tx dock DOCK w With. i ike the big dpp timber er
dock OF Brooklyn, is under repairs. This last
will cost heavily. chiefly IN consequence Of a
inexpensive work of repair, which must never
thelcss be made.
New York No. . docks, which are OF the same
size, is to lengthen the gate or caisson by twen.
seventy.two feet on the bottom sill; to widen
the cross sections by a concrete supporting
wall along the sides; to support the affairs or
steps above; finally to replace by concrete all
tho timber in the abutment floor. except tho
piles, the new entrance, being also made of con
dock, or about 1865. 900 for the three.
The question may arise whether IL is not bot
tor to build new concrete docks outright. B1t
the board holds that since this last would take
about two years in each cnsc. while concrete en-
frances could DO furnished for the existing
five docks in six or eight months, the latter Is
the better plan. Besides, even these altera-
lions would enable all these docks to take in,
at light draught. the heaviest of our battle
ships, which at present some of them could not
do. Thus our docking facilities for the most
important vessels would be materially enlarged
within a short time. and whatever was done
would be permanent, leaving the remainder of
the docks to BIO replaced with concrete at q
later day.
The great point Of controversy, both as to
tho boards recommendation and that of Ad:
miral Matthews, will be in regard to the use of
concrete instead OF timber. Timber dry docks
have been familiar here for over. forty years,
and 1t is pointed out that out OF thirty craving
docks on the Thames near London twenty-five
are wholly and six partly built Of wood. About
fifteen years ago a naval board. one of whose
members was Capt. A. T. Mahan. then n Com.
was only from 80 TO 40 per cent. OF that of a
stone dock, and that it could be built in about
one-third OF the time.
1t also reported that three Boston docks.
completed in 1854. 1855, and 1864. were still
in use at that time, 1882. and although there
nal piles and floor and keel timbcrs and abut-
ments " ere still sound. Those docks exist to.
day. Concrete costs less than stone. but much
moro than wood.
Still the opinions of the exports alrcady.spoken
OF point to The usc.of concrete for the next series
trance of existing ones. So far us the general
public is concerned. the chief desire Is to secure
adequate dOckage facilities for our ships,
leaving the technical question of the best ma
terial and method of construction to those who
are capable of dealing with 1t.