Improvements in and relating to Twin Hull Ships.
Year: 1890

page_text: Date of Application, 22nd Aug., 1890-Accepted, 4th Oct., 1890
COMPLETE SPECIFICATION.
Improvements in and relating to Twin Hull Ships.
I, ANDREW JAMESON PURDY, a subject of the Queen of Great Britain, residing at
No. 708, 11 Street North West in the City of Washington District of Columbia,
United States of America, Draftsman, do hereby declare the nature of this invention,
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The invention relates to twin hull ships, and the armour thereof.
Figure 1 is a longitudinal section 'nearly central on one of the hulls; Figure 2 is
a deck plan; Figure 3 a diagramatic side elevation of the upper part of one of the
hulls; and Figure 4 is a similar diagram with side armour omitted.
Lines a-a and bare supposed to be similar in Figures 1 to 4.
Figure 5 is a sheer draft or diagram showing longitudinal lines complete of both
hulls; Figure 6 is a cross-section amidships through boiler rooms; Figure 7 is a
cross-section through turrets; Figure 8 a sectional diagram of a modification with
triple hull; and Figure 9 is a front and rear section of Figure 5.
The hulls, A, A, are alike, and are complementary to each other. The hulls are
connected above the water line amidships by the protective deck, C, and by the upper
works above said deck. Below the water line the hulls are connected by a number
of struts, D, D, which present sharp edges in the direction of movement.
The adjacent sides of the hulls at the midlength section are about vertical and
parallel. These vertical sides curve gradually forward and aft into approved curved
lines for a sharp hull. See Figure 5.
The reduced or flattened sides of the hulls are exactly complementary, and the hulls
counterbalance each other.
A belt of armour, F, extends along the outer side of each hull, extending vertically
from below the water line to the protective main deck, C. The armour terminates
forward and aft at the turrets, G, being merged in the walls of the turrets. There
are two fixed turrets, G, on each hull, extending to the outer side but not to the inner
side of the hull.
The protective deck, C, is about horizontal and extends from turret to turret fore
and aft, and from one armoured belt to the other athwart ship. Forward from the
rear line of the turrets, the protective deck drops to nearly the level of the water
line, and is merged with the curved deflective deck, C, as indicated by heavy broken
lines Figure 1. The after connection of armoured decks is substantially similar. The.
passages through the protective decks are near the turrets, and thus protected by the
turrets.
The deflective deck, C¹, extends forward (or astern) from a turret to the end of
the hull, the edges being curved so as to be below the water line, and to join the
double bottom of the hull.
The space within the hull above the curved deflective deck, C', is divided into
suitable compartiments to serve as coal bunkers. An opening, I, in the deflective
deck, at the inner side of the turret, leads to a coal chute, O, which inclines down
towards the furnaces. The openings, I, are covered with suitable shutters when
desirable, and coal bunkers, (as ✗) are provided below deck to contain fuel enough
to last during an engagement. The openings, I, in the decks are protected from
fire except through a small arc, by the turrets. Suitable tramways or trolleys
(dotted lines) lead through the coal bunkers to the mouth of the coal chutes.
The magazines, K, are directly below the turret, and the passage from the maga-
zine to the turret may be through the circular casing, L, which rests on a lower
deck or other suitable support and sustains the turret cover. Ammunition will be
carried up from the magazine by power lifts.

page_text: The space below the armoured deck is divided into suitable compartments for boiler
rooms, engine rooms, store rooms, cabins for crews, &c. The officers' quarters may
be above the protective deck, C, amidships when the twin hulls are connected.
The double bottoms, M, and N, are connected by plates forming a large number
of water-tight compartments. The double bottom extends up to the armoured belt on
the outer side amidships, but at the inner sides of the hulls may terminate at about
the height of the boiler room floor. (See Figure 7.) Forward and aft the double
bottom should extend as high as the lower edge of the deflective deck.
The conning tower, R, may be fitted to the port hull only. Sinoke stack, S, and
ventilating pipes, T, should be protected by armour for some distance above deck, and
by proper gratings.
Each hull will have its complete complement of boilers, engines, and propellers,
as if it were a complete ship, but will not need to carry armour on the side toward
its twin.
The twin hull construction described is a compromise between a divided hull, which
is well known, and a double symmetrical hull, also well known. The parallel space
between the hulls is designed to permit the free flow of water away to the stern,
preventing any great accumulation of wave between the hulls, and minimizing the
strains tending to break the hulls asunder.
The hulls described will have moderately high free boards, giving the ship good
sea-going qualities. By reason of the combined hull construction, the ship will have
great stability. As each vessel has its own propelling power, the speed of the ship
may be as great as that of any other vessel, while the stability is much greater than
that of any vessel with a single hull.
Figure 8 shows a triple hull construction in which a central symmetrical hull
having perpendicular sides amidships, is connected to two outer hulls having each a
flattened inner side. It is apparent that the same general arrangement may be
carried to any convenient number of hulls, the sides of the midship section being
parallel and about vertical, and verging into curved lines forward and aft.
Some of the advantages of my construction are that the deflective decks give
practically complete protection, being perforated only at the coal chutes. There is
little danger that both hulls will be disabled at the same time, and unless one hull be
very seriously injured the other will furnish excess of buoyancy enough to float her.
The ship will be easy and comfortable in all weathers.
I have shown conical covers to the turrets, but make no claim thereto. The guns
may be mounted in any suitable manner in the turrets and broadside batteries.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed. I declare that what 1
claim is :
1. A twin hull ship, the hulls having the outer sides on usual lines, and the inner
sides of the midship sections vertical and parallel, but merging forward and aft into
curved lines nearly similar to the outer lines of the hulls, the twin hulls being connected
above and below the water line, substantially as described.
2. A twin hull ship having adjacent sides of the midship sections about vertical
and parallel, and merging with curved lines forward and aft, and a protective deck
extending over the midship section of both hulls and the space between said hulls at
the midship section substantially as described.
3. A plurality of hulls having adjacent sides of the midship sections vertical and
parallel, and extending into curved lines forward and aft, a single deck extending
across all the midship sections, and struts connecting the hulls below the water line,
the parts combined substantially as described.
4. The combination with the twin hulls of a ship, of an armoured belt extending
along the outer side of the midship section of each hull and a protective deck
extending across the space between the armoured sides of the hulls, substantially as
described.
5. A twin hull ship having two turrets on each hull, said turrets being connected

page_text: by an armoured belt extending along the outer side of each hull from turret to turret,
substantially as described.
6. The combination of the twin hulls, two turrets on each hull, side armour extending
from turret to turret at the outer sides of the hulls, a protective deck reaching from
armour to armour and from turret to turret and deflective decks on each hull forward
and abaft the turrets.
7. A twin bull having a midship section provided with a horizontal protective deck,
a belt of armour at the side of each hull, a turret in which the armour is merged
forward, and a curved deflective deck forward of each turret and at a lower level.
than the horizontal deck into which deck the horizontal deck is merged by an incline
at the side of the turret, substantially as described.
Dated this 22nd dow of A 1000
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.