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auger for shipbuilding purposes. They cut a smooth and circular hole
which can be accurately plugged, thus minimising the rapid decay that
takes place around the treenail and dowel fastenings in wooden ships. So
serious became this evil that between 1834-48 treenails in H.M. Navy were
almost entirely superseded by copper bolt fastenings.

Preparatory to cutting a hole with either of these tools, it is necessary
to bore a small guide or leading hole equal in diameter to the outer stem ;
the subsequent feeding is given by a thread on the stem that fits the hole.
The dowel -engine, which is provided with brass head and adjustable steel
blade and cutter, is still largely used for cutting holes to take the wood plugs
or dowels fitted over the heads of deck and sheathing bolts on modern steel-
built vessels.



COMPOSITE SHIP CONSTRUCTION.

639. Half midship section of a composite ship. Lent by the
Nelson Dock Co, 1876. N. 1442.

This represents an experimental vessel, built about 1859, and classed at
Lloyd's for 15 years.

Each frame is built up of thin timber with an angle iron on each side, a
plan which resembles that patented by Mr. T. Bilbe in 1856. The beams
are angle irons, with pieces welded in for connecting with the frames. The
outside planking consists of two thicknesses of wood, laid diagonally at
right angles to one another, and an outer sheathing arranged horizontally.

640. Midship section of a composite ship. (Scale 1 : 24.)
Lent by the Nelson Dock Co, 1876. N. 1441.

This represents a vessel built experimentally and classed at Lloyd's for
11 years.

The main feature of the design consists in the general use of T-iroii for
frames and beams. The frames have the table of the I 1 inside while the
external spaces are packed with wood, another variation 011 Bilbe's con-
struction of ] 856. The keel, keelson, floors, and outer skin are of wood.



193

641. Model of midship section of a composite ship. (Scale
1 : 18.) Lent by Messrs. Short Bros., 1876. N. 1447.

This represents a vessel of about 400 tons, in which the frames are made
of single angle-bars, except at the floors, where there is a reversed angle-bar ;
the keelson is a single plate girder. Deck, side and bilge stringers of iron
are fitted.

642. Model of midship section of composite ship. (Scale
1 : 24.) Lent by Messrs. Short Bros., 1876. N. 1446.

This represents a proposed vessel in which the external plating is
arranged between the frames, the plates being flanged on all four sides and
bent to the general form of the ship, the webs of the angle -bar frames
consequently point outward and external planking is fitted. The deck beams
are also angle-bars, while the keel is a partly- intercostal plate.

643. Drawings sliowiug composite ship construction. (Scales,
full size, 1 : 6 and 1 : 12.) Lent by Lloyd's Register of
British and Foreign Shipping, 1876. N. 1440.

This series of drawings was prepared in 1866 by Mr. H. J. Cornish, of
Lloyd's, to illustrate the suggestions made by Lloyd's Committee for the
construction and classification of vessels on the composite system, then
coming into extended use. The general idea is to brace the transverse
frames by outside iron ties or riders before planking ; the other details are
varied as in iron ships.

Eight drawings show half midship sections of vessels from 100 to 2,500
tons register, with the lower planking of elm.

Five drawings show modifications of the upper deck waterway and
bulwark stanchions for vessels of 900 tons register.

Two drawings show respectively inside and outside views of iron sheer
and bilge strakes, with the method of connecting the diagonal ties ; they
also show the outside planking.

Two drawings show various forms of keelson, while a section of the stem
and full-size details of the rivets and joints are shown on two others.

644. Drawing of a composite ship. (Scale 1 : 24.) Lent by
Lloyd's Registry of British and Foreign Shipping, 1876.

N. 1439.

This represents a three-masted sailing vessel of about 1,000 tons
register, built to conform with Lloyd's rules o 1866 for composite vessels.

The transverse frames are of reversed angle-bars ; ovitside these is
riveted an iron sheer strake 1 in. in breadth for every 6 ft. of the vessel's
length and a bilge strake 66 of the breadth of the sheer strake ; both are
joined by butt straps between frames. Riveted to the frames between
these strakes are diagonal ties or riders, making a structure resembling a
diagonal truss. The planking is bolted to these ties and angle-irons, the
butts coming midway between adjacent frames, on plates riveted to them.

645. Model of midship section of a composite ship. (Scale
1 : 24.) Lent by Messrs. Short Bros., 1876. N. 1445.

This represents a vessel conforming with the recommendations of Lloyd's
Committee of 1866 (see No. 643).

The main frames are formed of continuous reversed angle-bars, the
alternate ones having reversed angles fitted to the turn of the bilge only ;
fore-and-aft stringers and diagonal tie-plates bind these together and also
the upper-deck beams in the way of mast stresses. The deck beams are of
plates, with double angle-bars along the top edges and the keelson is a
continuous plate girder.

u 6773. N



194

646. Model of midship section of a composite ship. (Scale
1 : 24.) Lent by Lloyd's Registry of British and Foreign
Shipping, 1876. N. 1436.

This illustrates a system ol combined wood and iron construction
which differs somewhat from that approved by Lloyd's Registry in 1866.

The iron floors, together with the intermediate wood filling-floors, are
combined with a wood keel and keelson similarly disposed to those of a
wooden-built vessel. Single and double longitudinal angle-bars above the
floors, with a closely-fitted wooden ceiling, take the place of side plate-
keelsons, bilge keelsons, and bilge strakes ; the outer frame angle-bar is
cut off at the garboard strake of shell planking. Iron beams, pillars, and
deck stringers are fitted, but there is no iron sheer strake. There is a
light diagonal bracing riveted inside the frames between the upper and
main decks, and also a thin outer sheathing of wood worked diagonally
from the level of the main deck beams to the garboard strakes.

647. Models showing planking 011 composite vessels. (Scales,
1 : 4 and 1 : 12.) Made by the Admiralty, 1887.

N. 1769-71.

These represent in detail the usual method of attaching the shell
planking to vessels built with iron frames. The planking is in two layers,
so disposed that each strake in either layer acts as an edge-strip to strakes in
the other, thus providing a good edge connection for both. Each strake of
the inner planking is attached to each frame by two bolts, screwed into
the outer flange and locked by an internal nut. The outer planking is
secured to the inner by through copper bolts, disposed as shown, and clinched
upon a brass washer at each end.

(a) shows how the butt joints at the ends of the planks are distributed.

(b) shows how the edge joints are distributed and fastened.

(c) shows in detail the method of making the end joints of the inner
planking, by scarfing and connecting them together at a frame. The planks
of the outer thickness are plain- butted and secured by two through-bolts on
each side of the butt.

For models showing experimental methods of working the outside
planking of composite vessels (see Nos. 639, 640 and 646).

648. Models of sections of a composite gun vessel. (Scale
1 : 24.) Made by the Admiralty, 1887. N. 1790-1.

A half midship section and a forward longitudinal vertical section are
shown of a small composite worship, similar to H.M.S. " Avon/' 467 tons
displacement, built 1867.

The details of the transverse framing, intercostal keelson, bilge, side
and deck stringers, together with the deck and outer bottom planking
are represented.

There is no middle-line wooden keel, but a flat keel-plate and a vertical
intercostal iron keelson takes its place. There is a " collision " bulkhead
carried to the upper deck, and the keelson is shaped to the contour of
the bow and connected with the upper deck so as to strengthen the wooden
stem.

649. Half block model showing composite ship construction.

(Scale 1 : 48.) Lent by Messrs. Robert Duncan & Co.,
1876. N. 1426.

This represents the construction of the sailing ships " Napier " (formerly
the " James Nicol Fleming ") and " Otago," built in 1869 by Messrs.
Duncaii & Co.

There are two decks, with a poop 54 ft. long and a forecastle 33 ft.



195

The frames, deck beams, floors and keelsons, are of iron; the longi-
tudinal ties, with cross ties or riders (coloured blue), are to give addi-
tional rigidity. Longitudinal black lines show the seams of the wood
planking, which is secured to the frames and riders by brass bolts. The
keel, stem, sternpost, and rudder are of wood. Yellow metal sheathing was
attached to the shell planking.

Length, 207 -3 ft.; breadth, 34 -5ft.; depth, 20-25 ft.; gross register,
1,050 tons.

650. Sections showing composite ship construction. (Scale
1 : 4.) Made by the Admiralty, 1887. N. 1766-7.

These show, in transverse and side elevations respectively, details of the
usual structural arrangements at the lower portions of a composite cruiser
for the Royal Navy.

The transverse floors are continuous from bilge to bilge, the vertical
keel plates being fitted intercostally. These latter are connected to the
reversed frame bars by double continuous angles on their upper edges,
and to the floor plates and flat-plate keel by half-staple angles on each
side. The wooden keel and the two thicknesses of external planking are
secured together and to the steel framing of the ship by means of bolts
disposed as shown. A method of fitting false keels in two layers to
prevent damage to the main wooden keel and its fastenings in the event
of grounding is also illustrated. The longitudinal girders at each side of
the middle line are constructed of intercostal plates, secured to the floors and
to inner and outer continuous stringer plates by short connecting angle-bars.

651. Half midship section of a composite cruiser. (Scale
1 : 24.) Made by the Admiralty, 1887. N. 1792.

This represents a cruiser similar to H.M.S. " Hyacinth," of 1,420 tons
displacement, built 1881-3.

It shows a wood keel, intercostal side and middle-line keelsons, bilge
keel, and bilge stringer. A " turtle-back " watertight deck, combined with
a longitudinal coal-bunker bulkhead, extends from the outer planking to
the upper deck, for the protection of engines and boilers.

With the large increase in size and engine -power of cruisers of the
Royal Navy, the composite construction has been generally abandoned in
favour of steel-built hulls wood-sheathed if necessary.

652. Model of a " tabled scarf" joint. (Scale 1 : 4.) Made
by the Admiralty, 1887. N. 1764.

This is generally used for connecting the timbers composing the keel of
a wood or composite vessel.

The " tabling " serves the two-fold purpose of a dowel and of a stop
for the caulking ; its raised portion is one-half the length and one-third
the breadth of the scarf. Vertical through-bolts, carefully clinched in
position, bind the two parts of the scarf closely together. The model shows
also the rebates on the keel, formed to receive the lower edges of the bottom
planking.

653. Model of a " hooked scarf " joint. (Scale 1 : 4.) Made
by the Admiralty, 1887. N. 1765.

This shows a vertical scarf used to connect the lengths of a wood
ribband or harpin.

A small square hole or key- way in the centre receives two keys, one
from either side, which when driven tightly in place force the lip ends into
recesses on the adjoining pieces. The joint is further secured by treenails
or bolts, so that it shall withstand the stresses due to the harpin being bent
to the curvature of the ship's side.



N 2



196

IRON AND STEEL SHIP CONSTRUCTION.

654. Model of side of H.M.S. " Warrior," showing armour-
plating. (Scale 1 : 24.) Contributed by John Scott Russell,
F.R.S., 1868. N. 1268.

This shows the original method proposed for securing the armour to the
" Warrior " (1861), the first armoured iron ship. Wherever armour was to
be fixed, the shell plating was to be provided externally with vertical and
horizontal girders attached to it by angle-irons. Into the rectangular
recesses thus formed the armour plates were to be secured.

This idea was abandoned in favour of closely- spaced vertical frames
inside the shell plating, leaving a shelf for the 4 5-in. armour and 18-in.
wood backing. The armour plates were held in position by flush conical-
headed through-bolts secured by nuts inside.

655. Sectional model of a warship. (Scale 1 : 24.) Contri-
buted by H. Caudwell, Esq., 1863. N. 947.

This represents a design for an armoured war- vessel of light draught,
patented by Mr. Caudwell in 1863.

A projecting belt of wrought iron near the water-line is provided as a
protection against ramming and penetration by shot in this locality. A
sloping roof of thin armour gives f urther protection from gun fire and also
prevents " boarding." Apertures in this roof are provided for ventilation
and as gun ports, but they are fitted with sliding shutters. Above this
protective roof a light temporary promenade deck can be carried.

The United States coast defence ironclads " Dunderberg " and
" Onondaga," of 7,060 tons displacement, built during the Civil War
of 1861-5, resembled this design in several respects.

656. Midship section of Halsted's warships. (Scale 1 : 24.)
Presented by Messrs. R. Napier and Sons, 1867.

N. 1178 and 1186.

This shows the internal construction of the combined broadside and
turret vessels proposed by Yice- Admiral E. P. Halsted in 1866.

The spar or flying deck has the diagonal trussing patented by Mr.
B. Napier. On the upper decks are the turrets, the ship's rail being fitted
to hinge overboard when in action. On the main deck, which is 9 ft. high,
are the turret communications and supports ; also the broadside batteries
and a gangway port on each side. The lower deck, which is 7 5 ft. high
shows the turret supports and wing passages. The hold is 19 ft. deep, and
through it the turret supports are carried down to the double bottom,
which is 4 ft. deep. Further details of the turret are given in an adjacent
model (see No. 711).

The armour belt extends 6 ft. below the water-line and 6 ft. above, with
plates 6 in. thick ; it has a backing of 6 in. of oak supported by Hughes's
patent hollow stringers and an inner skin, giving a total thickness of 18 in.
A short length of an actual stringer is shown ; the section is similar to
that of a bridge rail, but weighs 213 Ib. per yard.

657. Fore deck of Halsted's warships. (Scale 1 : 48.) Pre-
sented by Messrs. R. Napier and Sons, 1867. N. 1179.

This shows the arrangement made to permit of an end- on fire from the
forward turret, and the modifications thereby required in the support of the
spar deck.

658. Half midship section of a battleship. (Scale 1 : 24.)
Received 1874. N. 1394.

This midship framing of an iron-built armoured battleship of the
" Minotaur " class illustrates a transition stage in iron ship -construction



197

during the period 1861-5. Here, the lightened-plate frames, partly inter-
costal and partly continuous, foreshadow the modem "bracket" frames:
the longitudinals are continuous. There is a watertight floor to the boiler-
room space, but no inner-bottom plating is fitted and no complete cellular
sub -division is attempted. A reduction in the ordinary spacing of the
transverse framing was made at intervals so as to permit a pair of frames
to form the sides of each broadside gun-port. No special framing to
support the armoured side is shown. The influence of wood traditions is
evidenced by the rough-tree bulwark stanchions ; these were subsequently
displaced by the lighter and more economical iron-built combination of
topsides and hammock berthing.

A comparison with No. 659 will emphasize the many improvements in
constructional details.

659. Half midship section of H.M.S. " Bellerophon." (Scale
1 : 24.) Made by the Admiralty, 1887. N. 1784.

This vessel was constructed of iron at Chatham in 1865 from the designs
of Sir E. J. Reed : she is 300 ft. in length, 56 ft. in breadth, and 7,550 tons
displacement. In general structural features the " Bellerophon " shows an
advance in all preceding iron-built war- vessels. The " bracket " system of
framing and also the complete cellular double-bottom for two-thirds the
length amidships were here successfully introduced ; these features have
been retained, with slight modifications, in recent practice. Each bracket-
frame is formed of two small end-plates joined by short unforged frame-
bars at top and bottom and provided with short vertical bars at each end
for connection with adjacent longitudinals : this displaced the earlier single-
plate frame with joggled and stapled angle-bar connections. "Weight and
cost were thus considerably reduced by the new system.

Another important improvement was made by increasing the vertical
depth of all bottom framing. This added to structural strength and gave
easier access for cleaning and painting the enclosed compartments ; it
likewise provided extended facilities for the use of water-ballast.

Her armour is of wrought iron 6 in. thick, and it extends from 5 ft.
below the water-line to 15 ft. above, while amidships it is carried upwards
to the spar deck, so that it shields all of the guns. This model also illus-
trates an early method of stiffening the framing of the vessel behind the
armour by means of longitudinal girders, a departure that eventually
developed the deep web-franies with intercostal girders, afterwards
adopted in battleships. In subsequent vessels, owing to the increased
penetration of gun fire, this large area of broadside armour could not be
carried, and the thicker protection necessary was arranged as a narrower
belt about the water-line and around the vital portions of the ship (see
Nos. 664 and 668).

A water-colour drawing of this vessel under sail is shown in the Ship
Gallery (No. 91) and additional particulars are given on the descriptive
label.

660. Attachments for sheathing. Presented by T. B. Daft,
Esq., 1864-5. N. 1038.

These three specimens show means of protecting iron ships from fouling
by attaching sheathing of some other metal, at the same time avoiding the
rapid destruction of the iron skin through electrolytic action.

The first specimen shows a modification of methods patented in
1859-60. The iron skin is drilled with small holes which almost penetrate
it, and into these plugs of vulcanite are driven. The yellow metal
sheathing, -04 in. thick, is insulated from the skin by a layer of felt and
rubber, and is attached by nails driven into the vulcanite plugs.

The second specimen has zinc sheathing 045 in. thick fixed in the same
way, except that no insulating sheeting is inserted. The galvanic action
oxidises the zinc and causes it to flake off, carrying the barnacles with it.



198

A third specimen with drawing shows Mr. Daft's last patent of 1863.
The butts and edges of the shell plates are kept apart a distance of 5 in.
and covered by internal straps ; into these open joints teak or vulcanite is
fitted and caulked, the plates being left rough from the shears or else
bevelled. The zinc sheathing is nailed 011 through these strips.

661. Half midship section of a sheathed corvette. (Scale
1 : 24.) Made by the Admiralty, 1887. N. 1793.

This represents the framing of an iron-built unarmoured war-vessel
similar to H.M.S. "Inconstant," of 1868. Two thicknesses of wooden
sheathing are attached to the outside plating.

The transverse framing consists of deep intercostal floor-plates, alternated
with shallow frames of reversed angle-bars continuous through the keel and
longitudinals. The vertical keel and all longitudinal frames have also
their lower portions intercostal and upper portions continuous throughout
the ship.

The external planking, though greatly stiffening the shell plating of the
vessel, is chiefly for the purpose of securing the copper sheathing, the anti-
fouling properties of which enable this class of ship to make lengthened
cruises in foreign waters without necessitating " dry docking " and
cleaning. (See No 662.)

662. Sections showing wooden sheathing. (Scales 1 : 4 and
1 : 12.) Made by the Admiralty, 1887. N. 1772-5.

These show portions of the outside planking, plating, and framing of a
steel vessel, sheathed with wood in one or two thicknesses.

The bolts securing the wooden planking to the hull are disposed as
shown, and they are screwed into the skin plating until their heads are well
below the surface of the exterior plank ; a wooden plug is then fitted over
the head and a nut and washer are added inside the ship. The practice of
fastening both thicknesses of plank by means of through -bolts is not
universal, the outer thickness in many vessels being secured to the inner
thickness of plank by wood screws of naval brass.

The primary purpose of planking outside the steel hull is to give an
efficient attachment to thin copper sheathing, the poisonous properties of
the salts formed by which, in sea water, make it a valuable under- water
covering to vessels, particularly if designed for lengthened cruises abroad.
Copper and steel when in metallic connection in the same water produce an
electrolytic action that injuriously affects the hull of the ship, and as a
special precaution against accidental contacts a double thickness of plank
was fitted as shown. Recent tests, however, having demonstrated that
metallic contact might exist even under these circumstances, a return has
been made to the original practice of a well- caulked single thickness of
planking.

For illustrations of proposed methods for securing zinc and brass, as
anti-fouling sheathing, to the hulls of iron ships, see Nos. 660 and 663.

663. Model of attachment for sheathing. (Scale 1 : 6.) Lent
by Messrs. Hooper and Nickson, 1870. N. 1322.

This method of fixing metal sheathing to iron ships was patented by
Messrs. Hooper and Nickson in 1869.

Iron eye-bolts are first riveted or screwed through the iron skin ; then
planking is fitted over these bolts and secured by pins, driven in the thick-
ness of the wood and each passing through one of the eyes. This planking
is given a coat of preservative paint and then covered by nailing upon it
usual brass sheathing, care being taken that the nails do not touch the iron
skin or the bolts,



199

664. Half midship section of a battleship. (Scale 1 : 24.)
Made by the Admiralty, 1887. N. 1785.

This represents the midship framing of a central citadel battleship of
the " Collingwood " class, 1882.

The combination here shown of continuous longitudinal frames with
short transverse "brackets" between, has been generally adopted for the
construction and sub-division of the cellular bottoms of warships since 1865 ;
the modifications since introduced being mainly for the purpose of securing
greater rigidity. The model shows also the arrangement of the shell
plating, topside framing, armour-shelf, armour, and wood backing, as well as
the general construction of (a) the transverse watertight bulkhead, (6) the
fore-and-aft, middle-line watertight bulkhead, (c) the fore-and-aft, wing
watertight bulkhead.

In later vessels, longitudinal coal-bunker bulkheads were fitted, thus
giving the extra protection afforded by about 10 ft. of coal around the
boilers and engines (see No. 667).

665. Half .section of a battleship. (Scale 1 : 24.) Made by
the Admiralty, 1887. N. 1786.

This section, taken either before or abaft the double-bottom, shows the
general construction of the unarm oured ends of the central-citadel battleship
of the i; Colling wood " class, 1882.

Continuous Z-bar frames, extending from vertical keel to lower deck,
take the place of the bracket-framing used amidships. The positions, and
details of connections, of the longitudinal girders and bulkheads, also of
the lower, protective, main, and upper decks are shown.

666. Section of bow framing of a battleship. (Section 1 : 24.)
Made by the Admiralty, 1887. N. 1789.

This is a longitudinal, middle-line section of the fore end of a battleship
of the " Admiral " class, 1882.

The stem piece is a solid forging (see No. 695) with a projecting spur
or ram, and is supported against the severe stresses to which it may be
subjected by : (a) the abutments of main and upper decks ; (6) the hori-
zontal frames or breast-hooks, six in number ; (c) the horizontal rani plate



Online LibraryScience Museum (Great Britain)Catalogue of the naval and marine engineering collection in the ... museum .. → online text (page 27 of 58)