We have from time to time given accounts in this journal of the system
of towage by hauling on a submerged wire rope, first experimented upon
by Baron O. De Mesnil and Mr. Max Eyth. On the river Rhine the system
has been for many years in successful operation; it has also been used
for several years on the Erie Canal in this State. We publish from
_Engineering_ a view of one of the wire rope tug boats of the latest
pattern adopted for use on the Rhine.
The Cologne Central Towing Company (Central Actien-Gesellschaft für
Tauerei und Schleppschifffahrt), by whom the wire rope towage on the
Rhine is now carried on, was formed in 1876, by an amalgamation of the
Rührorter und Mulheimer Dampfschleppshifffahrt Gesellschaft and the
Central Actien-Gesellschaft fur Tauerei, and in 1877 it owned eight wire
rope tugs (which it still owns) and seventeen paddle tugs. The company
so arranges its work that the wire rope tugs do the haulage up the rapid
portion of the Rhine, from Bonn to Bingen, while the paddle tugs are
employed on the quieter portion of the river extending from Rotterdam to
Bonn, and from Bingen to Mannheim.
[Illustration: ROPE PULLEY FRICTION BRAKE.]
The leading dimensions of the eight wire rope tugs now worked by the
company are as follows:
Tugs No. I. to Tugs No. V. to
IV. VIII.
Meters. ft. in. Meters. ft. in.
Length between
perpendiculars 39 = 126 0 42 = 137 10
Length over all 42.75 = 140 3 45.75 = 150 1
Extreme breadth 7.2 = 28 8 7.5 = 24 5
Height of sides 2.38 = 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 11¼
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. V. to VIII. the proportion has been made 1:11.82. In tugs I. to IV.
the diameter of the clip drum is 2.743 meters (9 feet), while in the
remaining tugs it is 3.056 meters (10 feet).
From some interesting data which have been placed at our disposal by Mr.
Thomas Schwarz, the manager of the Central Actien-Gesellschaft fur
Tauerei und Schleppschifffahrt, we learn that in the tugs Nos. I. to IV.
the hauling machine develops on an average 150 indicated horse, while in
the tugs No. V. to VIII. the power developed averages 180 indicated
horse power. The tugs forming the first named group haul on an average
2,200 tons of cargo, contained in four wooden barges, at a speed of 4½
kilometers (2.8 miles) per hour, against a stream running at the rate of
6½ kilometers (4.05 miles) per hour, while the tugs Nos. V. to VIII.
will take a load of 2,600 tons of cargo in the same number of wooden
barges at the same speed and against the same current. In iron barges,
about one and a half times the quantity of useful load can be drawn by a
slightly less expenditure of power.
The average consumption of coal per hour is, for tugs Nos. I. to IV., 5
cwt, and for tugs Nos. V. to VIII., 6 cwt.; and of this fuel a small
fraction (about one-sixth) is consumed by the occasional working of the
screw propellers at sharp bends. The fuel consumption of the wire rope
tugs contrasts most favorably with that of the paddle and screw tugs
employed on the Rhine, the best paddle tugs (with compound engines,
patent wheels, etc.) burning three and a half times as much; the older
paddle tugs (with low pressure non-compound engines), four and a half
times as much; and the latest screw tugs, two and a half times as much
coal as the wire rope tugs when doing the same work under the same
circumstances. The screw tugs just mentioned have a draught of 2½ meters
(8 feet 2½ inches), and are fitted with engines of 560 indicated horse
power.
During the years 1879, 1880, and 1881, the company had in use fourteen
paddle tugs and ten eight-wire rope tugs, both classes being--owing to
the state of trade--about equally short of work. The results of the
working during these years were as follows:
================================================================
| | Freight | Cost of | Degree
| | hauled | haulage in | of
Class of tugs. | Year. | in | pence per | occupation.
| | ton-miles. | ton-mile. |
----------------------------------------------------------------
Paddle | 1879 | 31,862,858 | 0.1272 | 0.686
" | 1880 | 31,467,422 | 0.1305 | 0.638
" | 1881 | 28,627,049 | 0.1245 | 0.537
Wire Rope | 1879 | 15,407,935 | 0.1167 | 0.614
" | 1880 | 17,289,706 | 0.1056 | 0.615
" | 1881 | 17,593,181 | 0.0893 | 0.536
================================================================
The last column in the above tabular statement, headed "Degree of
Occupation," may require some explanation. It is calculated on the
assumption that a tug could do 3,000 hours of work per annum, and this
is taken as the unit, the time of actual haulage being counted as full
time, and of stoppages as half time. The expenses included in the
statement of cost of haulage include all working expenses, repairs,
general management, and depreciation. The accounts for 1882, which are
not completely available at the time we are writing, show much better
results than above recorded, there being a considerable reduction of
cost, while the freight hauled amounted to a total of 54,921,965
ton-miles.
[Illustration: WIRE ROPE TUG BOAT, RIVER RHINE.]
As regards the wear of the rope, we may state that the relaying of the
first rope between St. Goar and Bingen was taken in hand in September,
1879, while that between Obercassel and Bingen was partially renewed the
same year, the renewal being completed in May, 1880, after the rope had
been in use since the beginning of 1876. The second rope between Bonn
and Bingen, a length of 74¾ miles, is of galvanized wire, has now been
2¾ years in use, during which time there have been but three fractures.
The first rope laid was not galvanized, and it suffered nine fractures
during the first three years of its use. The first rope, we may mention,
was laid in lengths of about a mile spliced together, while the present
rope was supplied in long lengths of 7½ miles each, so that the number
of splices is greatly reduced. According to the report of the company
for the year 1880, the old rope when raised realizes about 16 per cent.
of its original value, and allowing for this, it is calculated that an
allowance of 18.7 per cent. per annum will cover the cost of rope
depreciation and renewals. Altogether the results obtained on the Rhine
show that in a rapid stream the economic performances of wire rope tugs
compare most favorably with those of either paddle or screw tug boats,
the more rapid the current to be contended against the greater being the
advantage of the wire rope haulage.
* * * * *