CA1230784A - Ice zipper - Google Patents

Abstract

ABSTRACT
In an apparatus for breaking and clearing paths in ice co-vered waterways, it is known to have an upward thrusting, taper-ed plough blade, which is articulatable vertically in two places, at the elbow joint and at the mounting trunnions. In addition, a pair of lateral flexing, scoop-shaped wings or gates are app-ended to either side of the plough, to clear debris left by the plough blade. Limited fendering is provided for in the lower, outboard regions of the plough. A pyramid-shaped horn forms the leading point of the blade.
The apparatus is mounted to the front of a ship and secured by means of booms and trunnions or fulcrums situated ahead of midship, well above the waterline. Connecting booms extending aft the trunnions are counterweighted. The actuations are power-ed and controlled by hydraulic pump systems or cable and winch drums.
This apparatus is distinguishable from other inventions in that it articulates, while others are fixed, conventional ice-breakers have a compromised angle of attack, preset, that does not and can not address the fact that ice thicknesses vary and that the uptimum energy efficiency is achieved when the broken ice, on the lifting surfaces of the plow, is quickly dumped to the rear sides of the plow, allowing new brash ice to flow over the lifting sufaces. Clearing of broken ice from the upward thrusting plough surface is directly related to the ice break-ing performance.
My invention has infinite angle and depth variation, with-in any foreseeable requirements.

Description

~2307~34 ABSTRACT
In an apparatus for breaking and clearing paths in ice co-vered waterways, it is known to have an upward thrusting, taper-ed plough blade, which is articulatable vertically in two places, at the elbow joint and at the mounting trunnions. In addition, a pair of lateral flexing, scoop-shaped wings or ga-tes are app-ended to either side of the plough, to clear debris left by the plough blade. Limited fendering is provided for in the lower, outboard regions of the plough. A pyramid-shaped horn forms the leading point of the blade.
The apparatus is mounted to the front of a ship and secured by means of booms and trunnions or fulcrums situated ahead of midship, well above the waterline. Connecting booms extending aft the trunnions are counterweighted. The actuations are power-ed and controlled by hydraulic pump systems or cable and winch drums.
This apparatus is distinguishable frorn other inventi.ons i.n that it articulates, while others are fixed, conventional ice-breakers have a compromised angle of at-taclc, preset, that does not and can not address the fact that ice thicknesses vary and that the uptimum energy efficiency is achieved when the brolcen i.ce, on the li.f-ti.ng surfaces of t:he plow, .is qlliclcly d~lmpecl ko the re~l.r si.cles o~ tlle plow, dllOWi.nCI rlow ~rasLI i.ce l.o flow over the li.~ting su.~dces. Cleari.n~ of brolcerl i.ce frorn t.he upward thrusting plough surface is directly related to the ice brealc-i.ng performance.
My i.nvention has infinite angle and depth variation, with-in any foreseeable requir(~ t:s.
SPECIE`ICATION
This invention relates to a powered, controlled icebreaking apparatus, mounted to the front of a sea going vessel.
Standard ice breaking vessels rely chiefly on downward pres-sure, of a fixed angle stem, of a prow on a shi.p. the weight of ~L~3~

the ship is counted upon to break the ice and, then sink the broken chunks, thus clearing a path. A point to mention here is, that water is a cushion that renders ice more resilient.
A second method tried is, an upward thrusting, fixed stem angle prow, integral to the vessel itself.
The dificulties encountered by the upward attempts were:
The swept back, dihedral surfaces were too blunt, being only about ten percent of the beam width. Clearing of the broken ice from the plough surface is directly related to the icebreaking performance, an 80 percent dihedral is desirable. At low speeds, the lifting surface of the prow being invariable, thus, in thin ice cover, the movement of ice, as it lifted out of the water, di.d not have sufficient resistance ahead of itself to force it to flow smoothly over the ever increasing pitch upward slope of the prow, causing the prow to bulldoze the whole floe. Since the desired flow of ice debris is related to the angle of attack versus the speed of the vessel, a fixed angle of attack is very limited, as speedsvary, so the angle should vary. The ratio of theaxial to athwartship velocities, has to be improved, to avoi.d ice bui.ldup forward of the shoulders and eventual jams.
A reduced entrance angle and some changes near the shoulders to reduce the lifting changes of the ~oving i.ce, would tencl ko lc~ep the i.ce f lowi.ncl.s.i.dew~s and baclc.
The stem of t.he bow was a spli.tter blade whi.ch grooved i.t-self into the ice floe edge, in heavier encounters, and ceated additi.onal fricti.on and very li.t-tle lifting thrust.
Overloading of the sloped bow region, above the waterline was a factor in energy loss, because oE the incontrollable i.ce lifting slope angle, on the previous upward thrusting prows.
The difficulties encounter.ing the conventional bow forms, i.e: downward thrusting, at all fixed stem angles of attack are:

The vessel relies on power and weight versus buoyancy of ice; the cushionning effect of the water; the friction of the 1~3~)~78~

bow on snow coveri overcomming gravity by lifting it's mass out of the water, onto the ice edge, in order to break through.
In this type of icebreaker, ice brea~ing is accomplished by a combination of crushing the ice and lifting the ship. The conventional icebreaker requires enormous power, at ever incxea-sing cost, to do this. In heavy ice of two or more meters thick, the conventional icebreakerspends a large portion of time, just rammi.ng and extracting, mostly extracting, in order to build up momentum for the next charge. The resulting approach by archite-cts and engineers is, merely to increase power and size, with exponential growth in cost, because as weight and size of an icebraker increases, so does the energy loss, due to friction against the snow covered ice and also energy loss, due to great-er weight and mass being propelled.
The demonstration that ice can be broken by means other than brute power should encourage us to-think more deeply about conventional methods and what we can do to ameliorate the factors operating, aside from merely increasing power and si.ze.
It should be noted that friction from snow covered i.ce is a large factor, approaching fifty percent of energy requirement, on a downward thrusting hull.
Wakes of conventional icebred1~ers ~1re .le-Et. cJ.u~.te.red w~t.h brash, conlai.ni.ng large b.1.ock~ oJ. i.ce, I.hL1l .i.mpefle follow-up shi.ppi.ng. These blocks coalesce, :Ereeze, and the path disappears soon after.
I have found that, these disadvantages may be overcorne or greatly di.mi.nished, by provi.di.ng the ship with a variable pi-tch plough, whi.ch can be set to the most beneficial angle, at the moment when the situation di.ctates.
The way the pi.tch of the plough can be varied is accomp-lished by, actuati.ng the elbow joint hydraulic power pumps, exerting pressure between the plow and it's controlled sup-porting booms. Thi.s elbow joint is linked to the booms ~L~3~ 34 by large bearing hinges.
An important feature is the way this plow is mounted.
Trunnions on both sides of the ship, allow the whole plow to be elevated right out of the water and lowered to any desired depth, even below the ship~s draught, this is very convenient, as you will see later.
Another important feature of this invention is, the incor-poration of a pair of scoop-shaped wings, hinged onto the dis-charge ar~ of the plow. these wings are able to flap in a hori-zontal plane, or to put it in another way, are independently movable on an axis around the hinges, laterally. Their purpose is to extend the breadth of the plough blade, to clear the bro-ken ice chunks, that may otherwise fall back in the cleared path, in the space between the plow discharge area and the bow of the S~lip .
The front point of the plough is tapered laterally and ver-tically, with the thin end foremost.
A pyramid-shaped horn pointing upwards is fixed permanently to the forward taper of the plow.
The horn is normally under the ice cover and does not con-tact with the underside of the ice, until such time when the need arises, to lift or hammer a large floe. I'his is done by actuating the joinks at the -trunnions ~lncl or khe elbc)w. 'I'he bdSe of the horn is prot:ruclincl below klle bl~lde erld to serve dS d drop hammer.
The blade of the plow is concave and dihedrdl, able to be articulated vertically, d configurdtion thal is designed to break, lift and discharge brash ice, to the sides and above the trench walls, leaving a clean lane.
The stem of the blade is rounded, and since the stem is the portion of the blade that is normally first to contact the ice obstacle, as is intended, a rounded cylindrical face of the stem will avoid scoring and grooving the underside, and reduce ~30~
friction. The diameter of the stem is in the range of ~5cm. The forward tip of the stem, back to the upper three quarter dis-tance, is very straight, having no bends, this is necessary to have a definite control on the angle of contact between the ice edge ~nd the stem.
Supporting booms provide a means of elevating and lower-ing the plow unit, mounted to either side of of the ship, longi-tudinally, jointed by fulcrum trunnions, counter-balanced by weights and having a centre of gravity wel.l back of the bow, so that the weight of the plow and ice will not tend to make the vessel pitch fore, The principles on which the apparatus is designed to operate are:
Ice cover on Arcti.c waters seldom exeed ~.2 meters in thickness. The average thickness of second year ice is 2.1 meters; (ref The Arnerican Peoples Encyclopedia 1953 edition).
Snow cover on ice floes is nearly always present, in one form or another, and friction on the i.ce hrea]cing bow due to sn.ow cover, can be as high as 50% of power requirement, on a downward thrusting bow;

An upward thrusting bow has no snow to contend wikh. and it i.s always lubri.ca-ted by w~l~.er.
T}le Archl.me~e~s l?r.i.nc.ip:~e of cl.l.spl,lcelrlent was evi.clent to me as I di.scovered, qui.te by accident, when I experime~nted breaking ice on a frozen pond w.;.th a small model, -toy si.æe boat, that when movinct ahead, having a sharp downward thrusting bow, I could break khrough the i.ce with very little progress, maybe only five or six inches per run. That which astounded me most at that time was, that the progress astern, clearly showed, is a much better icebreaki.ng process than going ahead.

The penetration astern was a steady speed albeit, slower than in water free of ice. Note that the prop did not contact the ice.

~3~78A~

Years later, thinking back to the frozen pond experience, I hypothesized tha~: Either a vacuum or just a void in the wdter, supporting the ice dstern~ WdS sufficient to cause the i.ce to sag and give, once deprived of it's water cushion. I
concluded that, if this is true, by attacking the ice from below with a plough, for instance, the water cushion would be a help, rather than a hindrance;
I also observed that when a piece of ice broke away from the main floe, the piece alone rose somewhat, above it's ori-ginal level, my thoughts in this respect were inconclusi.ve as Idid not toil with it further. It could be that, the larger the ice floe, the lower it's level, or else as water freezes over d pond the flrst crust covering the surface, wi.ll keep growing in depth from beneath only, thus having a natural positive up-ward pressure, ahd was bei.ng held down by the original crust which had anchored to the shores of the pond. The specific gra-vity of ice is .92 approximately. 'L`his may be irrelevant, yet one is inclined to thi.nk that just that little 8~/~ of mass that was kept below it's natural level would be equivalent to the slight depression caused by the propeller backwash in the astern mode, experienced with the toy boat, powered by batteries.
An upward thrusti.ng bow form, i.s adjllsted t.o stri.ke l:he edge of the i.ce pdCk at between 22 tc~ ~5 de~l. clown .i.rol~ the hoxi.zont.dl, usi.ng l.he co~cept of l:ape~r o.r wedgi.rlcl ].ift action, by exerti.ng ever i.ncreasing pressure under the i.ce sheet, as the shi.p moves forward, backed by the enertia of many kilo-tonnes, wi.ll shatter the i.ce -to explode upwards, the hi.gher the speed developed by the shi.p, the smaller the si.ze of the chunks and the smoother the flow of these chunks over the sur-face of the plow blade.

Unlike downward -thrusting conventional~bow forms, my in-vention does not require forces sufficient to lift the vessel out of the water. It requires just the amount needed to.

lZ36~78~

To break a small portion of ice, measured at any one in-stant, as that ice just ahead;
To lift that ice that is immediately in front and on top of the bladei To propel itself, as in calm waters; and To operate hydrauli.c pumps or winches and normal shi.pboard equipment.
Another advantage of the upward thrusting bow form is fur-ther explained by the fact that the contact surface of the ice on the lif-ting surface of the plough, is always lubricated by water, helping to reduce the friction factor. We all know how an ice skate blade glides so well on ice, because of the thi.n film of water formed under it, between the blade and the ice.
It i.s my opi.ni.on that -the power requirements will approxi-mate 60% of conventional methods, for equal size vessels, a 40%
saving on energy alone.
In drawings which illustrate embodiment of thi.s in~rention, Figure 1 is a pictorial view of this embodlment, Fi.gure 2 i.s d plan view of this embodi.ment, and Figure 3 is an elevation of figure 2.
The apparatus .illustrated comprises a plougll 1, whi.ch is adapted to an exi.sti.nq shi.p, 11 :i.s d ~.i.lhOllette of 9uch a .9h:i.p~
The plouq]l may be oE any s~ al)le breadl-.]-l, to mdtcll the i.nten-ded shi.p's beam, but i.n the form shown and approxi.mately the same proporti.ons.
The wi.ngs 2, swi.ng laterally on their hi.nges, connected to the shoulders of the plough, the swinging is controlled by hydrauli.c pumps. The stem 3, is cylindrical and may be hollow, and welded to the main component 1. The horn ~, is solid and welded to the stem 3. The drop hammer 5, is solid and firmly welded to the undersi.de of 1. 6 is a splitter blade, welded -to the top end of the stem 3, pointing forward, as illustrated.
The elbow joint 7, i.s the connecti.ng link between the plough ~23C1~7l34 assembly and t.ll'' boo.,l~, this joint is flexible vertically and power cont.roll~d,. ~endering is provided on the lower portion o~ t.he ~low. ~r1Le booms 8, are connected to the ship through the trunnions 9, and are power contxolled t~o move in a vertical arc, the whole assembly is counterwei.shted by the weights 10, which can be adjusted for best performance and to obtain the most ef-fective balance.
The complete assembly is fabricated of high grade steel, T1 or better. The welding beads on the steel plate junctions on the fricti.on surface of the plough, must be grounded complete-ly smooth, to reduce the friction from adhearing ice granules.
The friction surfaces of the assembly may be coated with fric-ti.on reducing agents. Not shown in the drawings is the ribbing and the ribband web, welded to the reverse surface of the plow, this ribbing should be, as is normal, for structures of this kind, where puncturing and deformation are a concern.
The operator of the icebreaker is situated in a prominent position, where he can observe the effectlveness of the ice-breaking process. The operator has a number of control levers that enable hi.m to manipulate the plough and vary the pitch angle of the stem, by actuating the lever conl:roJ.ling tlle.~ elbo~
joi.nts 7. ~n ex~mple o:F t'hi.s ~ldvdnl.llcle :i.s: Wilen d pl.al-c~ 'r :ice, i.n the reg.i.orl of 13 by 7 meters i.n .5i~e~, iS struclc a:breadth, by the stem, at an angle of contact of near 25 to 30 deg. vertical, the hydrodynami.c forces on the leading eclge of khe i.ce plate are such that the plate will rotate, tumble forward, and roll under the plow and eventually t.he hull. This is time and energy consumi.nc3. When this condition is predictable, the operator can reduce the angle of attack in order to strike and break the ice plate, and if necessary, ram it from below the ice to con-tact with the tip of the horn 4. In this example the operator may use the flexibility of both joints 7 and 9, to accomplish this feat.

~3~)7~34 The trunnion joints 9, are used to lift and lower the complete assembly for the following reasons:
To be repaired and serviced, thus eliminating costly dry-dock charges. Actually repairs could often be performed in situe if the need arose;
It can be lifted out of the water to reduce drag when the vessel is plying cleared waterways;
It can be used as a drop hammer to break through a hummock or ice ridge;
It can be used as an upward ramming hammer from below the ice; and It can be vibrated verti.cally to dislodge piles of brash ice and aid the flow of ice chunks, to the rear outboard of the discharge area of the plough.
A common occurrence in ice, is when a large flow connects with the stem of a ship, and is near the point of balance, or centre of pressure in drag, it remains stuclc there in front of the stem, it is too small to offer enough resistance to en-able ice breaking acti.on by crushing, spli.tting or sinking, therefore it remains up front being pushed for long distances, costing much delay and energy loss. The abi.li.ty to hammer tlle obstacle or, even jusk vary khe at:ti.kll~e o~ kh~ 6lem wi.l.l .re-solve this problem.

Claims (5)

"The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follow:"

1. A power operated plough to be mounted to the front of a ship for breaking and clearing shipping paths in ice co-vered waterways, said plough comprising a main upward thrust-ing tapered component, upper, outward shoulders on said main component, two wings, one on either side of the said main com-ponent, hinged to said upper, outward shoulders to permit la-teral swing of said wings, a pair of beams, one on either side of said ship, flexible joints, said main component connected to said beams by said flexible joints at the forward ends of said beams, fulcrum bearings above the waterline and ahead of midship, said beams connected to said ship by said fulcrum bearings, counterpoise weights, said counterpoise weights attached to said beams rearwardly of said fulcrum bearings.

2. The plough defined in claim 1, wherein the flexible joints are power controlled so the pitch angle of attack is va-riable and controllable.

3. The plough as defined in claim 1 or 2 wherein each fulcrum bearing contains a trunnion which is power controlled so the plough can be elevated and lowered in a vertical arc.

4. The plough as defined in claim 1 or claim 2 wherein the main component includes a cylindrical stem extending central-ly along the top of the main component with the forward three quarter portion thereof being straight.

5. The plough defined in claim 1 or claim 2 wherein the main component at the front thereof includes a pyramid shaped horn pointing upwardly and a ball shaped drop hammer extending downwardly.