434 NICHOLL§~c5 SEAMANSHIP AND NAUTICAL KNOWLEDGE

The Midship Pillars in the figure are riveted to the beam above and
to the beam below, the bottom ends of the hold pillars being riveted
to the top of the "centre keelson." The pillars are not merely supports
to prop up the beam above but act as ties to bind together the upper
and lower beams

The Transverse Sections, shaped to the form of the ship and consisting
of frames and reversed frames, floor, pillar, beam and beam knees are all
practically the same and spaced from 21 to 36 inches apart according
to the dimensions of the ship. The frame spacing is reduced at the
ends of the ship to strengthen the hull against the effect of panting
and pounding when in a seaway, as the frames being much straighter at
the bow and stern are less able to resist inward pressure. liefer to the
plan of Caledonian Monarch and note that the 28-inch normal spacing
of frames is reduced gradually to 24 inches from frames No. 14 aft
and from frame No. 168 forward.

The Longitudinal Framing keeps the transverse sections in their
correct relativ^ positions. Note the "centre keelson," composed

J------.TTJkC

% Fig. 14.—A Centre Keelson.
of a vertical plate with two angle bars on its lower edge and two on its
upper ^dge. A flat plate, called a "rider" plate, is riveted to the hori-
zontaj[ flanges of the top angles, the whole combination forming a very
strong centre girder or backbone for the ship. The angles on the lower
edge of the centre plate are riveted to each reversed frame and to a short
**lug" piece on the top edge 6f the floor, all as further illustrated in
Iftguie 14.
The Centre Keelson.—A is the vertical plate standing on the floors.
EL and JB3 the stiffening angles on its upper and lower edges respectively,
0 the rider plate riveted to the horizontal flanges of angles Bv D, a
foundation plate laid along the top of the floors and riveted to the
reversed frames Q9 to the lug piece E and to the horizontal flange of
angle #2. F is the floor plate.