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Past and Present Coast Guard Vessels for the Arctic: Encyclopedia Arctica 9: Transportation and Communications
Stefansson, Vilhjalmur, 1879-1962

Past and Present Coast Guard Vessels for the Arctic

Past and Present COAST GUARD VESSELS FOR THE ARCTIC, YESTERDAY AND TODAY

Captain Edward H. Thiele, USCG
With the advent of U.S. Revenue Cutter Service (Coast Guard) operations
in the Arctic it was apparent that a special type of craft would be necessary to cope
with the problems of extreme cold weather, ice and operations in remote sparsely
inhabited areas. Because of the lack of experience in this type of operation, the
logical solution was arrived at by investigating the types of ships then in existence
and plying these remote areas.
At that time whaling and sealing in the polar regions were in full swing,
and through bitter experience a type of vessel had been developed that would with–
stand the rigors of arctic navigation within the limits of the facilities available.
It was common practice, especially with whalers, to make cruises into the Arctic of
several years duration, freezing in during the winter months — sometimes purposely,
other times unavoidably. As a result of this type of operation, the hull form, construction
and means of propulsion were governed by the probability of becoming ice-bound and
being caught in heavy squeezes.
The U.S. Navy had acquired two special type craft, which had originally
been constructed as arctic sealers, for use as relief vessels in connection with the
ill-fated Greeley expedition. After the successful completion of several missions to
the Arctic under the Navy, these two vessels, the Bear and Thetis , were transferred to
the "Revenue Cutter Service" in 1885 for patrolling Alaskan territorial waters.
The construction of these two vessels was modern and in accordance with the
best practices of the period, and proved to be highly successful for the duty in
tended. The hulls were built in Dundee, Scotland, by A. Stevenson and Sons, about
1874, and the boilers and machinery in Greenock, Scotland, by the Greenock Boiler and
Iron Works. Details, showing the inboard profile and midship section, are shown in
Figs. 1 and 2. The vessels were similar. The characteristics of the Bear were as
follows:
Length over all 198' 0"
Beam molded 28' 6"
Draft (maximum) 18' 2"
Displacement tonnage 1,700
Main propulsion Reciprocating steam
Power 350 IHP
Auxiliary propulsion Sail
Rig Barkentine
Hull Wood
Keel American Elm, 14 1/2” x 14 1/2”
Frames German Oak, 12” x 14” (Approx.)
Frame Space 16 1/2” (Approx.)
Bottom planking Elm, 4 1/2”
Side planking Pitch pine, 5 1/4”
Inner planking Pitch pine, 4”
Ice sheathing Iron bark doubling, 2 1/2”
By the 1870's it was recognized that power was essential to work in northern
waters, but the possibilities of losing or damaging the propeller or rudder, if caught
in the ice, were ever present. With no assistance available and no communications,
the only solution in case of underwater damage was to rely on sail. No ship would
dare enter the A rotic without two sets of sails (one spare).
The Bear was operated by the Coast Guard in arctic waters from 1885 to
1926. In 1927 the Coast Guard built the Cutter Northland (Figs. 3,4) to replace her.
The Bear had proven satisfactory for routine Coast Guard duties during her many years
service in the Bering Sea, and so, naturally, many of her characteristics were incorp–
orated in the Northland . The principal characteristics of the Northland were:
Length over all 216’
Beam, molded 39’
Displacement at 15 Ft. mean
draft
2,050 tons
Number of main propulsion
diesel engines
2
Total shaft horsepower 1,000
Speed, knots 11.5
Auxiliary propulsion Sail
Rig Barkentine
Builder Newport News Shipbuilding Co.,
Newport, Va.
Although the Northland had some of the same general characteristics as her
predecessors, the Bear and the Thetis , many improvements were embodied in her design.
The massive wooden hull of the earlier ships was replaced with steel. Special
attention was given to providing hull strength to withstand the crushing forces of ice
and to limit flooding in case of hull damage. The waterline plating of the hull varied
from 1-1/4” thickness at the bow to 1” thickness at the sten. Other strakes of
plating varied in thickness from the maximum of 1-1/4” to a minimum of 1/2”. It was
expected that this plating would be sufficiently heavy to resist the abrasive and
tearing action of ice which this vessel might normally be expected to encounter. The
vessel was of riveted construction and was subdivided by nine transverse watertight
bulkheads. In addition to the function of limiting flooding, these transverse bulk–
heads were designed as strength members and contributed towards the vessel's ability
to withstand crushing.
The Northland was built with a typical (European type) cut-away bow that had
been successfully in arctic operations by other nations. Although the Northland could
break light ice, she was not built primarily as an ice-breaker. She was built with
sufficient strength to withstand the contacts with ice accompanying navigation in
fields of broken ice; and with sufficient endurance to permit operating away from a
base for long periods of time, and to give the crew a reasonably good chance of sur–
viving until the thaw, should the vessel become entrapped.
Although great strides had been made in the design of machinery and
materials, navigators were still reluctant to take a ship into arctic ice without sails as an auxiliary means of propulsion. As a result, the Northland was rigged
as a barkentine ship to satisfy the old line experienced arctic skippers. In the
process of changing from wood to steel ships the propulsion machinery was given
intensive thought and study. The advantage of diesel economy was recognized, but
a means of providing rapid maneuverability and protection for the propeller and main
engines was desired. After weighing all factors it was decided to adopt diesel
electric drive, and as a result one of the first successful installations of this
type was made. As an added precaution to protect the propeller and the main motor,
an electromagnetic coupling was installed in the line shafting between the main motor
and the propeller. This feature was later eliminated when it was found that the
coupling would throw out in a sea-way when the propeller broke water.
The reliability of the main power plant was of utmost importance. The refore
two main generators were employed, supplying current to a single double-armature motor.
In this manner it was possible to provide two independent sources of power to a
single propeller, thus increasing the reliability of the motive power. We note that
in all modern arctic vessels this principle of multi units has been adopted.
Although aviation was still somewhat in its infancy in 1926, the specifications
for the Northland included a boom for hoisting a seaplane to the after deck. A sea–
plane was not operated from this vessel to any great extent until World War II, when
the Northland was used on patrol duty off Greenland, nearly twenty years after she
was built.
The Northland proved herself a worthy successor to the Bear , and was used
in arctic operations from 1927 until 1946. The Northland was designed for extended
cruises into the Arctic and for work in broken ice fields, but it was never intended
that she should be able to break or force leads into heavy ice. The Coast Guard
subsequently built several other vessels with ice operating features, including the
Calumet Class (1934-1935), and six vessels of the Escanaba Class built during the
period from 1931 to 1935. Much was learned from the ice operation of these vessels
in regard to the desirability of various types of propulsion machinery, the design
precautions necessary to insure proper operation of the machinery in ice, and the the structural effects of ice operations upon the hull.
Coast Guard experience in the Arctic indicated the desirability of having
vessels designed not only for operating in ice, but also capable of breaking ice. A
study of the entire problem was instituted in 1937, including a review of all of the
date obtainable on the characteristics andperformance of all of the ice-breakers ever
built. A representative was sent to Europe to inspect and gather information on ice–
breakers built for the Soviet Union, Sweden, Denmark and Holland. Investigations were
made to find the most effective hull form for breaking ice, and to develop the proper
relation between displacement, hull strength and horsepower. Also, all available in–
formation on actual operating experience was reviewed. The results of this study were
incorporated into the design of a group of 110’ harbor cutters built in 1939. These
small vessels were eminently successful as ice-breakers, so many of their characteristics
were included in a group of 180’ buoy tenders built in 1941, and in the Storis , a 230’
vessel built in 1941 for operating off Greenland.
The culmination of this series of vessels was the Wind Class (Figs. 5-6),
the first of which was completed in 1944. Some features of the early Northland appear
in the Northwind and her smaller prototypes. All of this series of ice-breakers are
powered by multiple-engine direct current diesel electric plants. This type plant
offers economy in space and fuel consumption, flexibility of operation, and dependability.
It also makes possible the use of pilot house control to permit fast and accurate
maneuverability while working in ice, thereby minimizimg the possibility of damage. The
magnetic clutch used on the Northland was not used on these later ice-breakers, but
main motors of a light weight high capacity type have been used in order to reduce the
rotating mass attached to the propeller.
The general characteristics of the Wind Class vessels are as follows:
Length over all 269’
Maximum beam 63’ 6”
Normal draft 25’ 9”
Normal displacement, tons 5,300 0
Speed, knots 16
Propulsion Diesel-electric
Number of main propulsion
diesel engines
6
Total shaft horsepower,
normal
10,000
Number of Propellers 3
Builder Western Pipe and Steel Co. of California
The use of double bottoms and wing tanks for fuel has been incorporated
in the larger recently-built ice-breakers. This provides protection from hull rupture
and also makes it possible to utilize every available bit of space for the great
quantity of fuel necessary for long periods of operation away from a base at full–
power operation, and for surviving long periods of immobilization if entrapped in ice.
The most outstanding feature of thw Wind Class is the hull form. Hulls of
the same relative type had proven fundamentally sound by experience gained with the
110’ Harbor Cutters and the 180’ Buoy Tenders. This hull is characterized by a cut–
away bow, and bow sections having a great amount of slope. These sloped sections cause
the buttocks to provide an angle of attack the same as the cut-away bow, and make it
easier for the vessel to ride upon the ice. The design also causes the breaking force
to be distributed over the entire forebody of the ship, and not concentrated at the
forefoot, as would be the case with more conventional lines. Since a vessel must
sometimes be backed into ice, the hull lines aft are very similar to the fore part of
the ship. The after propellers are kept as low as possible and in close to the hull
for protection, and the rudder stock is protected by a heavy cast fin, so constructed
as to give a breaking angle aft similar to the bow. There must be a very definite re–
lationship between the transverse strength of the vessel and the angle of flare of the
midship section, so that, in case the vessel is caught between ice floes, it will be
lifted before it is crushed.
The hull of the Wind Class is of all-welded construction, as was the case
with the smaller prototypes. Due to the use of extremely heavy plating and structure,
some unusual welding problems developed. The shell plating is of high tensile steel, varying in thickness from 1-1/4” at the keel to 1-5/8;” at the ice belt. This plating
is backed up with truss type transverse frames spaced on 16” centers, capable of giving
a uniform panel strength throughout the hull. The transverse strength is obtained by
making the decks and bulkheads strength members.
These vessels are designed to operate in temperatures as low as minus 50 degrees
F. The entire hull and superstructure above the waterline is insulated with 5 inches
of cork, and provision is made for isolating the central portion of the ship as winter
quarters in case of a freeze-in. Also, some provision had to be made for the removal
of ice forming topside. Such ice may be removed by chipping or by thawing with warm
water. A large supply of warm water is provided for this purpose by utilizing the
cooling water discharged from the main and auxiliary engine heat exchangers.
Experience has shown that, in successful ice-breaking and ice-working
operations, a means must be provided for freeing the ship if it becomes wedged into the
ice. On smaller vessels it is customary to roll the vessel by swinging the rudder, but
in the case of the larger ships other means must be provided. The Wind Class ships are
constructed with heeling and trimming tanks. The heeling system permits the shifting
of 240 tons of water ballast from one side of the ship to the other in an 80-second
cycle, thus inducing a rolling motion of about 8° form the vertical and preventing the
skin of the hull from freezing in if the vessel is stopped by the ice. The trimming
system permits the shifting of water ballast (120 tons) between the fore and after peak
tanks, thus giving a change of trim of approximately 5 feet.
The underwater appendages of an ice-breaker are very susceptible to damage
by ice, and propellers are a problem that require particular attention. Single screw
vessels provide the most protection, because of the position of the propeller on the
centerline behind a skeg, but the amount of power that can be absorbed is limited. Of
necessity, the diameter must be kept small to permit broken ice to pass over the blade
tips. On small vessels a single propeller is used in all cases, but on larger vessels
the power is distributed between two or more propellers. At present there are two
distinct types of ice-breakers in general use. The "European Type" consists of a
cutaway crusher bow, with all power being applied to propellers aft. The "American Type" consists of a cutaway crusher bow, but with a propeller forward as well as
propeller or propellers aft. The latter type was developed on the Great Lakes during
the nineteenth century. Both the "European" and "American" type vessels have distinct
advantages, depending on the operation to be undertaken. The "European Type" is best
suited when working alone in extremely heavy ice such as is encountered off the East
Greenland Coast. Forcing leads through heavy ice floes is known as "ice working." The
"American Type" is far superior for straight "ice breaking" and for convoying other
vessels through ice where the ice-breaker must work without benefit of leads. This,
of course, can only be done in ice which is not beyond the breaking capacity of the ice–
breaker. In the case of the Wind Class vessels the two types have been combined, in
that the bow propeller can be installed or left off as operational requirements dictate.
Propellers of the Wind Class vessels are solid nickel steel construction.
The after propellers are designed to give the ma x c imum thrust while the vessel is in the
stalled position. The forward propeller is used as a low efficient pump for dredging
ahead of the vessel or for creating a wake along the skin of the hull to wash broken
ice clear. No a ttempt is made to protect the bow propeller except by placing the tips
of the blades as far below the water li n c e as possible and keeping it well clear of the
ice-hull contact points. Provision is made for the removal of the bow propeller and
capping the bow tube when it is anticipated that the vessel will be sent into the high
Arctic where ice-breaking is impossible and where only ice working can be expected.
Power for the three propellers is furnished by six 2,000 h.p. diesel engines.
The power from these engines may be divided between the after shafts, giving 5,000 shaft
horsepower on each after screw, or it may be divided between the three shafts, giving
3,300 shaft horsepower each. Quick maneuverability is considered an essential in ice;
therefore, all modern arctic vessels are provided with pilot house control of the main
engines.
It has been found from experience with Coast Guard ice-breakers that assisting
other vessels through ice frequently terminates in a towing job. Accordingly, the ice–
breakers of the Wind Class are provided with very rugged towing equipment. A 40-ton automatic electric towing machine is provided with 300 fathoms of 2-inch steel towing
hawser. These vessels tow in open water in the customary manner, utilizing a long
hawser, but when towing in ice, an ice-breaker, when suddenly stopped by a hummock or
pressure ridge, is likely to be run down by the vessel being towed. To avoid such
difficulty the Wind Class vessels have a notch in the stern, so that the towed vessel
can be hauled in tight to prevent overriding and to keep the vessel in the clear water
directly astern. This arrangement offers an additional advantage, in that the extra thrust
from the vessel coupled astern may be used to assist in breaking ice.
Regardless of the size or strength of vessels built for arctic operations, it
is always the best and safest policy to pick leads where the ice is easiest to negotiate.
Planes used for reconnaissance are of inestimable value in this respect, and, therefore
all arctic vessels of a size permitting stowage are equipped for this type of equipment.
The Wind Class vessels are now provided with helicopter landing platforms. These
rotary wing planes are ideally adapted for ice reconnaissance and require no pen water
for take-off or landing.
Looking into the future of arctic operations and ships to accomplish this
mission, the experience being gained in the development of stronger hulls and more
powerful machinery indicates that eventually a type of craft will be devised that will
be able to negotiate most of the water-borne obstacles imposed by nature. To this end
the Coast Guard is committed in it responsibilities established by law as the protectors
of life and property at sea.
[U.S.R.C. THETIS]
In board profile U.S.R.C. "THETIS"
Thiele Fig 1
[U.S.R.C. THETIS]
Mid ship Setion U.S.R.C. "THETIS"
Thiele Fig. 2
[Ship] [Ship]
Midship Section U.S.C.G.C. "Northland"
Thiele Fig. 4
[Ship]
Inboard profile U.S.C.G.C. "North wind" "East wind"
Thiele Fig 5.
Midship Section U.S.C.G.C. "East Wind"
Fig. 6
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