CHAPTER IV.

BEAMS, PILLARS, AND DECKS.

Beams. The transverse framing we have been considering ends at the upper deck. To complete the transverse structure we have beams connecting the sides of the ship together at the level of the various decks and platforms. Beams not only tie the sides of the ship together, but they form the support to the decks and

platforms. Beams for decks on to which water is likely to come, as the upper and main decks, are made with a round down in order that the water may run to the side scuppers. The amount of this round is 9 in. in a 75-ft. battle-ship, and 6 in. in a 40-ft. cruiser. Beams to the lower protective decks are of

the same shape as the deck, usually level at the middle line and sloping down to the sides (see Fig. 12). Beams to the lower platforms and decks are level (see Fig. 19).

Beams in a large ship are spaced every 4 ft. where the frame spacing is 4 ft., and every 3 ft. at the ends of the ship. For a small cruiser the beams are

placed on alternate frames, i.e. every 4 ft.

MAIN DECK 2

TWO

15 LB.
BRACKET

THICKNESSES

17% LES

15 LB BRACKET

4 TEAK

Beams are most commonly formed of angle bulb (c, Fig. 8). Most decks are now covered with steel plating, and the angle bulb is then a convenient beam to use. When, however, a wood deck has to be laid direct on to the beams, as is sometimes the case, it is more desirable to have the tee bulb (d, Fig. 8), in order that the deck bolts may be worked zig-zag, and not in a direct line, as would be the case with the angle bulb. The tee bulb is a convenient form to use for skid beams for supporting the boats. A zed bar (e, Fig. 8) is a convenient form of beam when the flat supported forms the crown of a magazine in which teak lining is fitted. The lining can be bolted to the inner flange of the zed. In recent · ships, however, the lining to magazines has been dispensed with, so that this form of beam is not necessary. Angle bars are used as beams to flats in which the greater strength of the angle bulb is not required.

MIDDLE DECK. I

BEAM

20 LB

BRACKET

PLATE

FRAME

FIG. 34.

The connection of beams to the transverse frames is of great importance, as this, together with the transverse bulkheads, helps to prevent the racking of the ship due to rolling. To ensure an efficient connection, the beam is connected to the frame either by a beam arm, or a bracket plate. The beam arm is used where a neat appearance is desirable, as below the upper deck. To form the beam arm, the beam is cut at the middle of the

HALF

BEAM

CARLING

web and the lower part is bent down. A piece of plate is then welded in, giving the form shown in Fig. 33. The bracket is used in places where a neat appearance is not so desirable (Figs. 25 and 30). The usual depth of the beam arm or bracket is two and a half times the depth of the beam, so as to get a good riveted connection to the frame. In the special case of the beam to the middle deck, a bracket is not necessary, as sufficient rivets are obtained through the solid plate frame, which is worked beneath the armour (Fig. 34).

Half-beams and Carlings.-Some beams come in way of openings in the deck, as the engine hatch, ventilators, funnel

THROUGH

ВЕАМ.

casings, etc.

FIG. 35.

In these cases it is necessary to cut the beams; these are then termed half-beams. The inner ends of the halfbeams are connected to a fore-and-aft carling, which extends to the first complete beam at each end of the opening. Fig. 35 shows this arrangement for a small opening for a hatchway. The carling in this case is formed of an angle bulb of the same size as the

beams. It will be noticed how the half-beam hangs on the carling, which in its turn hangs on the through beams at the ends.

At large openings the carling is made exceptionally strong, because of the large number of half-beams hanging on to it. In Fig. 39 it is formed of a deep 20-lb. (in.) plate, with an angle. bulb in addition. The deep plate also provides a convenient attachment for the thin funnel casing. The specially large openings in the protective deck caused by the spread of the funnels as they go down to the boilers cut off such a large number of beams that some compensation

has to be provided. This is arranged for by running across at intervals, where possible, strong beams, usually built up as (h), Fig. 8.

The upper deck, forward and aft, needs to be strengthened in way of the blast of the heavy guns. This is arranged for by working fore-and-aft girders, well supported by pillars, under the upper deck.

Pillars. It is es

sential that the long

beams in a ship should

FIG. 36.

be supported at other places than at their ends, as, by thus supporting them, their capacity for bearing a load is greatly increased. In ships of the Royal Navy nearly every beam is supported by pillars or in some other way. Where possible, the fore-and-aft bulkheads are arranged so that the stiffening bars to the bulkhead act also as supports to the beams. One instance of this may be noticed in the cabin bulkheads below the upper deck aft in a battle-ship. In other places pillars are fitted. These pillars are

made of wrought steel tubes, a usual size for the 'tween-decks being 5 in. diameter and in. thick. In boiler-rooms and under

BEAM

PIN

SOLID
HEAD.

FIG. 37.

barbettes, where the pillars are very long, the diameter is 10 in. and the thickness in.

A considerable saving of weight results from using hollow pillars instead of solid, as well as the advantage of the greater stiffness of the hollow form of larger

NUT

PORTABLE

diameter. Thus, suppose a pillar if hollow could be 6 in. diameter and in. thick, and if solid 43 in. diameter (these two pillars in merchant shipbuilding would be considered of equal strength), the saving of weight by using the hollow form would be over a ton for every 100 ft. of pillar worked into the ship.

Hollow pillars must have solid heads and heels, and they must be secured at the top and bottom so as to form a tie between the decks as well as a strut (Fig. 36). Pillars are so arranged as to form continuous vertical lines fitting to portable of support right down to the pillar. bottom of the ship. The heel of direct to the beam, and not bolted This latter may be done when the

FIG. 38A. Heel

the pillar should be riveted to the wood deck (if fitted).