222 THE MARINE TERMINAL OF THE GRAND TRUNK 
20,000-TON PONTOON FLOATING DRY-DOCK. 
Referring to Plate 112, there will be seen the general design drawing of a 
20,000-ton pontoon floating dry-dock, description of which has been reserved 
until the last from the fact that, as previously stated, it was to be almost 
entirely constructed at and by the plant of which it is to be the principal 
feature. g 
This dock is to have an over-all length on keel blocks of 604 feet 4 inches, 
a clear width of 100 feet and a width over-all of 130 feet. The lifting ~ 
power is the aggregate of twelve pontoons of timber construction, each 
130 feet long corresponding to the width of the dock, 44 feet wide in a direc- 
tion corresponding to the length of the dock and 15 feet deep. These pon- 
toons are to be united by steel side walls or wings 38 feet high, 15 feet wide 
at the bottom and to feet wide at the top, the walls being divided so that 
the whole structure may be used under ordinary conditions as three separate 
docks, one of six pontoons, with an over-all length of 269 feet, and two of 
three pontoons each, with an over-all length of 164 feet each. The largest 
commercial ship upon the Pacific Coast at the present time is the Minne- 
sota; the outline of which is shown on the dock. ‘This vessel would have a 
dead weight in ordinary unloaded condition of approximately 18,000 tons. 
The machinery for pumping the dock will consist of centrifugal pumps 
operated by electric motors, the capacity of the equipment being sufficient 
to pump the entire lifting power of the dock in less than two hours. A 
detailed description of the pumping machinery will be given later. 
The structure as a whole is secured to the shore by the engagement of 
clamps on the dock with a vertical truss secured to the pile platform or pier 
in such a way that it is free to rise and fall with the tide, and when being 
raised or lowered with a ship. ‘The location of these attachments is such 
that when it is desired to use the dock in three separate sections, the bow 
section may be detached and moved around the corner of the pier work 
located as shown on the general plan alongside the platform, and secured in 
the same manner as provided for in its original position. To make the 
other two sections available as separate docks, it is only necessary to detach 
the middle section, comprising six pontoons, from the pier work and advance 
it the length of the detached section, when the sliding clamps upon the wings 
will coincide with those used for the previous section when the dock was 
operated as a whole. ‘This will allow ample space between the center and 
stern sections for the overhang without interference of vessels which may be 
docked on them. 
