8 = 7 11 2.38 = 7 11
Depth of keel 0.12 = 0 5 0.15 = 0 6

All the boats are fitted with twin screws, 1.2 meters (3 feet 111/4
inches) in diameter, these being used on the downstream journey, and
also for assisting in steering while passing awkward places during the
journey up stream. They are also provided with water ballast tanks, and
under ordinary circumstances they have a draught of 1.3 to 1.4 meters (4
feet 3 inches to 4 feet 7 inches), this draught being necessary to give
proper immersion to the screws. When the water in the Rhine is very low,
however, the water ballast is pumped out and the tugs are then run with
a draught of 1 meter (3 feet 3 3/8 inches), it being thus possible to
keep them at work when all other towing steamers on the Rhine are
stopped. This happened in the spring of 1882.

Referring to our engraving, it will be seen that the wire rope rising
from the bed of the river passes first over a large guide pulley, the
axis of which is carried by a substantial wrought iron swinging bracket,
this bracket being so pivoted that while the pulley is free to swing
into the line on which the rope is approached by the vessel, yet the
rope on leaving the pulley is delivered in a line which is tangential to
a second guide pulley placed further aft and at a lower level. This last
named guide pulley does not swing, and from it the rope is delivered to
the clip drum, over which it passes. From the clip drum the rope passes
under a third guide pulley; this pulley swings on a bracket having a
vertical axis. This third pulley projects down below the keel of the tug
boat, so that the rope on leaving it can pass under the vessel without
fouling. Suitable recesses are formed in the side of the tug boat to
accommodate the swinging pulleys, while the bow of the boat is sloped
downward nearly to the water line, as shown, so as to allow of the
rising part of the rope swinging over it if necessary.

The hauling gear with which the tug is fitted consists of a pair of
condensing engines with cylinders 14.17 inches in diameter and 23.62
inches stroke, the crankshaft carrying a pinion which gears into a spur
wheel on an intermediate shaft, this shaft again carrying a pinion which
gears into a large spur wheel fixed on the shaft which carries the clip
drum. In the arrangement of hauling gear above described the ratio of
the gear is 1:8.44, in the case of tugs Nos. I. to IV.; while in tugs
Nos.