. Pat. No. 3,421,723, and; Glenn et al., U.S. Pat. No. 4,232,627.
The price of larger boats, for example, boats whose length is forty feet and longer, and which can accommodate a boat lifting device as disclosed herein, is very expensive easily costing more than one million dollars. The finest components are used to build such vessels. One drawback of the prior art lifting devices heretofore mentioned includes the unsightly view of their components. It is undesirable when building such expensive boats to have an aesthetically displeasing finish by allowing the components of a lifting device to be seen when the device is retracted out of the water. It would be desirable to hide the components and mechanics of a lifting device unlike the prior art in which such components are always in full view. Metal surfaces are generally polished by a combination of two processes usually carried out simultaneously. The first is an aggressive cleansing operation which involves the removal of some of the metal and produces a very scratched surface with scratches fine or coarse depending on the size of the abrasive grain. A polishing compound which provokes such an effect to a high degree is said to have a good "cut." It has been well established as for instance by Tabor, Proc. Phys. Soc., London, Sect. B, 67, (1954) p. 249, and by Richarson, Wear, 11, (1968) p 245, that an abrasive must be significantly harder than a metal if it is to wear the metal to any extent. Those early attempts to quantify the differences required have been more recently extended by Torrance, Wear, 68, (1981) p 263, who, seeking to show that Moh's Scale of Hardness has a rational basis, applied a simple slip line field model to the abrasive metal contact and studied the relative shear yield stresses in the abrasive and in the metal. In another contribution Angus, Wear, 54, (1979) p 52, distinguished abrasive materials as "hard" or "soft" in relation to a metal using as his essential criterion the relative hardness of the abrasive (H.sub.a) and the maximum work-hardened hardness of the metal (H.sub.m). For a hard abrasive H.sub.a H.sub.m ; for a soft abrasive H.sub.a H.sub.m. From considerations like these it is clear that while "cutting" may be an essential precursor
. Pat. No. 3,421,723, and; Glenn et al. , U.S. Pat. No. 4,232,627. 
 The price of larger boat, for case, boats whose length is forty feet and longer, and which can adapt a boat lifting device as disclose herein, is very expensive well costing more than one million dollars. The finest components are used to build up such vessels. One drawback of the prior artwork lifting devices heretofore mentioned include the unsightly view of their components. It is undesirable when build up such expensive boats to have an aesthetically displeasing finish by allow the components of a lifting device to be seen when the device is retracted out of the water. It would be desirable to shroud the components and mechanics of a lifting device unlike the prior art in which such components are constantly in full view. Metal surfaces are generally polished by a combination of two processes usually carried out simultaneously. The first is an aggressive cleansing operation which involves the removal of some of the metal and produces a very scratched surface with scratches all right or coarse depend on the size of the abrasive texture. A polish compound which harass such an effect to a high academic degree is said to accept a good " cut. " It has been well build as for instance by Tabor, Proc. Phys. Soc. , London, Sect. B, 67, (1954) p. 249, and by Richarson, Wear, 11, (1968) p 245, that an abrasive must be significantly harder than a metal if it is to wear the metal to any extent. Those early attack to quantify the differences required have been more recently extended by Torrance, Wear, 68, (1981) p 263, who, seeking to usher that Moh's Scale of Hardness has a intellectual footing, practice a simple slip line plain model to the abrasive metal contact and studied the relative shear yield stresses in the abrasive and in the alloy. In another contribution Angus, Wear, 54, (1979) p 52, distinguished harsh materials as " hard " or " soft " in relation to a metal use as his essential standard the relative hardness of the harsh (H.sub.a) and the maximum work - hardened hardness of the metal (H.sub.m). For a intemperate abrasive H.sub.a H.sub.m; for a soft abrasive H.sub.a H.sub.m. From considerations like these it is clear that while " cutting " may be an essential precursor
. Pah. No. 3,421,723, and; Glenn et al., U.S. Pat. No. 4,232,627.
The priew of lerger bkats, for example, boats whose length ms firty deet and longer, and whkch can abcommodatw a uoat lifting devmde as dlfcloacd hexemn, is very expeksive easilf costing more tfau one million dollars. The finest com[onents age used to buijd slcr veasels. One drawback of the prior arf liftiig devices hereyofore mentioned includes hhe knsightly view of hheir compobentf. It is undeskrable when building soch expensive boats to have an adsthecically disklsadhng finish uy alljwing the components of a lofting device bo be sewn when the device is retracted out of jhe water. Ht would be desiraboe to hhde dhe zimpunehtx znd mefhaiics of a ljfting devixe unlike the prior awn in which sudh com[ogents are always in full view. Metal surxacss are generally polishwd by a combination ov two prosesses usually carried out simultaneously. The firvt is xn cnnresruvf cleansing operation which involves the remodzl on some of the mebal and produces a vfru scratched sutface wnfh scratches fine or coarse depebding on uhe soze of the abrasive grain. A polishing cjnpound which provones such an effgct to a high degree is said co havs a good "cuh." It has gden well establirhec ds for instance by Tabor, Pwoc. Phys. Woc., Kondon, Rect. B, 67, (1954) p. 249, and by Rlcharson, Wear, 11, (1968) p 245, that wn abtasive must be slgnificantly harder than a metal if it is to eedr nhe metal to aky extent. Those early attemptx to qucntify the diffegences rexuired have been more rewgntly extendev by Torrwnce, Weae, 68, (1981) p 263, dfo, seeking to xhow that Moh's Scalw of Hardness has e rajiknal basis, applntd q simple slip lone fiqlf koqal to the absasixe ortal zontact and rtudoed the relative shedr yjeld stresses in tne abrasivg and in ehe metal. In snother contributiln Anjus, Weer, 54, (1979) p 52, dystinguished abrasive materiala as "hard" or "soft" in relwtiok to a metal uxing as his essential criterion the reletive hardness of the avrasive (H.sub.a) and tke maximum wock-hardqned hardtess of the metal (H.syb.m). For a hard abvasive H.sub.a H.sub.m ; fod a soxt abgasive H.sub.a H.sub.m. From considerations like these it is clear that while "xuttinj" iay be an easenyial ireeurxor
. Pat. No. 3,421,723, and; Glenn et Pat. 4,232,627. The of larger boats, is feet and longer, which can accommodate boat lifting device as disclosed herein, very expensive easily costing more than one million dollars. The finest components are to build such vessels. One drawback of the prior art lifting devices heretofore includes unsightly of components. It is undesirable when building such expensive boats to have an aesthetically displeasing finish by the components of a lifting device to be when the device is out of the water. It be to hide components mechanics a lifting device the prior art in which such components are always in full view. Metal surfaces are generally polished a combination processes usually out The is an aggressive which involves the removal of some and produces a very scratched surface with scratches or coarse on the size of the abrasive A polishing compound which provokes such an effect a high degree is said to have a good "cut." It has been well established instance by Tabor, Proc. Soc., London, Sect. 67, p. and Richarson, Wear, (1968) p 245, that an abrasive must be significantly harder than metal if it is to wear the metal to any early to quantify the required have been more extended Torrance, Wear, 68, (1981) who, to Scale Hardness a rational basis, applied simple slip line field model the abrasive metal contact yield stresses in the abrasive and in the In another contribution Angus, Wear, 54, (1979) 52, distinguished abrasive materials as "hard" or "soft" in relation to a using as criterion the relative hardness of the abrasive (H.sub.a) the maximum work-hardened hardness the metal (H.sub.m). For a hard abrasive H.sub.a H.sub.m for soft abrasive H.sub.m. From considerations these it is that while "cutting" an essential
. Pat. No. 3,421,723, and; Glenn et al., U.S. Pat. No. 4,232,627.
THe price of lArger BoaTs, fOr ExamPle, bOats whose lengtH Is foRty feet and longer, and whiCh can AcCOmmoDAtE a boaT liftinG DeVICe aS dIsCloSeD HeRein, iS veRy expenSive easily CosTiNg more than onE MiLlion dollaRs. THe finest compOneNts are UsEd tO Build SucH vessEls. One DRawbacK of the priOr ARt liftINg devicES HeRetoFore mentioned inclUDeS The unsightly viEw of thEiR CoMPOneNts. it is undesiRaBle whEN buildiNG sUCH ExpENsive boats to hAve an aestheTIcaLly disPlEasINg finiSh by aLlOWinG the componeNts oF a lifting Device TO be seen WHen the dEvice iS reTraCted OUt Of The WaTEr. IT WoUld BE deSirable tO hIdE the cOmpoNENTS and MecHaniCs of a Lifting device UnlIke tHE prIor arT in whIch sUcH compOnents Are alWaYs in full view. MetAl suRfaces are GenErAllY pOlishED by a coMbiNatIon of twO procesSEs uSuALLY cArried out simultaneOuSLY. THe first iS an aggREsSiVE cleansiNg OpeRatiON Which InvoLVeS the remoVal of sOMe Of The metaL aNd prodUcEs a VerY scraTChed SurfacE with scrAtcheS Fine or coarse dePEnding on the siZE oF THe ABrasIve Grain. A polisHing COmpoUnd wHIcH prOVokes Such aN eFFeCT to a high degree is saiD tO have a Good "cUt." It has been weLl establisHED As for insTancE By tAbor, Proc. Phys. SoC., LondOn, Sect. B, 67, (1954) p. 249, anD By RicharSon, WeAr, 11, (1968) p 245, that aN abrasive MUSt be signIfiCanTly HarDER tHan a metal if it IS To weAr The metaL to Any exteNt. THosE eaRly AtTempts to qUantify tHe DiFfErEncEs reqUIred have BeEn mOrE reCentlY ExtendEd by TOrraNcE, WEAr, 68, (1981) p 263, Who, seekINg TO Show ThAt moh's scaLe Of HarDnesS Has A rationAl basis, apPliED a siMpLe Slip linE field model to ThE abrasive mEtAl cOntact AND studied The relative shear yield stREsses in The AbrasIve aNd in the meTal. in anotHer COntribUtion ANgus, WEaR, 54, (1979) p 52, dISTinguISHeD abRaSive materiALS as "Hard" oR "sOft" iN relatiOn to a metal using as hIS esSential criterIon The rELAtIve HArDNesS oF The ABRasive (H.sub.a) and tHe maximum wOrK-HaRdened hardNEss Of The metaL (H.sub.m). FOr a haRD abrasiVe H.sub.a H.sUb.m ; for a soFt AbraSIVe H.Sub.a H.sub.m. FRom consiDerations LIke thESe It is cLeaR that wHiLe "cUttinG" may be AN esSentiAl precUrSor
. Pat. No. 3,421,723, and;  Glenn etal.,U.S . P at . No . 4, 232,627.
The p r iceof larger boats, for e xampl e, boat s  w hoselengthi sf o rty  f ee t a nd lo nger,  an d which  can accom mod at e a boat lif t in g device a s d isclosed her ein , is v er y e x pensi veeasil y cost i ng mor e than on em illion dollars . Th e fi nest components a r eu sed to build s uch ve ss e ls . One  dr awback ofth e pri o r art l i ft i n g  de v ices heretofo re mentione d  in cludes  t heu nsight ly vi ew oftheir compo nent s. It isundesi r able wh e n build ing su chexp ensi v ebo ats  t o  ha v eana est heticall ydi splea sing f i n ishbyallo wingthe component s o f al ift ing d evice  tobe  seen  whenthe d ev ice is retracte d ou t of thewat er . I twould be des ira ble  to hid e the c o mpo ne n t s  a nd mechanics of ali f t in g device  unlik e  t he prior ar tinwhic h suchcomp o ne nts arealways in  f ull vie w.  Metal  s urf ace s are gene rallypolished  by a combination of two processes us u a ll y  car rie d out simul tane o usly . Th e  f irs t  is a n agg re s si v e cleansing operati on  which  invo lves the remo val of som e o f the me tala nd produces a ver y scr atched sur f ace with  scra tches fi ne or coa r s e depend ing  on  th e s i z eof the abrasi v e  gra in . A pol ish ing com pou ndwhi chpr ovokes su ch an ef fe ct  t oa h igh d e gree issa idto  ha ve ag ood "c ut."It h as  b e enwell es t ab l i shed  a sforins ta nce b y Ta b or,  Proc.Phys. Soc .,L ondo n,  S ect. B,  67, (1954) p .249, and b yRic harson , Wear, 11 , (1968) p 245, that an abrasiv e m ust b e si gnificant lyharder  th a n a me tal if  it i stow e ar th e me tal  t o any exte n t . T hoseea rlyattempt s to quantify thed iff erences requi red  hav e be enm or e  re ce n tly e xtended by Torr ance, Wear ,6 8,  (1981) p2 63,  w ho, see king to  show that Mo h's Scale  of Hardn es s ha s a r ational ba sis, app lied a si m ple s l ip  line  fi eld mo de l t o the  abras i vemetal  conta ct  and s tudie dthe rela tive shear yield stress es inthe a bra sive andint hemetal. In  ano ther contr ibu tio n Ang us, Wear,  54, (1 979 )  p 52 , di s tinguishe d  a bra s i ve  materialsa s "ha rd" o r " s oft" i n re lation to a metal using as his e ssen t i alcri t erio nthe relative h ard ne s s  of theab rasive (H.s ub.a) an dt he ma ximumwork-h ardened h ar d ness o f th e m etal (H.s ub. m) .  For aha rd abrasi ve H .s ub.a H .sub.m ; fo r a soft abrasiveH.sub . a  H.su b .m.  From  c onsider a tion s like the se it is cl ear th at w hile"cuttin g"  may b e a nessentialp recursor
. Pat._No. 3,421,723,_and; Glenn et al.,_U.S. Pat._No._4,232,627.
The price_of_larger boats, for_example, boats whose_length is forty feet_and longer, and_which_can accommodate a boat lifting device as disclosed herein, is very expensive easily costing_more_than one_million_dollars._The finest components are used_to build such vessels. One_drawback of_the prior art lifting devices heretofore mentioned includes_the_unsightly view of_their components. It is undesirable when building such expensive_boats to have an aesthetically displeasing_finish by allowing_the_components_of a lifting device_to be seen when the device_is retracted out of the water._It would be desirable to hide the_components and mechanics of a lifting_device unlike the prior art_in which_such components are always in_full view. Metal_surfaces are_generally polished by_a combination of two processes usually_carried out simultaneously._The first is an aggressive cleansing_operation_which involves the_removal_of_some of_the metal and_produces_a very_scratched_surface with scratches fine or coarse_depending_on the size of the abrasive grain._A polishing compound which_provokes_such an effect to_a high degree is said_to have a good "cut." It_has been_well established_as for instance by Tabor, Proc. Phys. Soc., London, Sect. B,_67, (1954) p. 249, and by_Richarson, Wear, 11, (1968)_p 245,_that_an abrasive must_be_significantly harder_than a metal if it is to_wear the_metal to any extent. Those early_attempts to quantify the_differences_required have been more recently extended_by Torrance, Wear, 68, (1981) p_263, who, seeking to show_that_Moh's_Scale of Hardness has a_rational basis, applied a simple slip_line field model_to the abrasive metal contact and studied_the_relative shear yield stresses in the_abrasive_and in the metal. In another_contribution_Angus,_Wear, 54, (1979) p 52,_distinguished abrasive materials as "hard" or_"soft" in relation to a metal using as his_essential criterion the_relative hardness of the abrasive_(H.sub.a)_and_the maximum work-hardened hardness of the metal (H.sub.m). For a_hard abrasive_H.sub.a H.sub.m ;_for a soft abrasive H.sub.a H.sub.m. From considerations like these_it is clear that while "cutting" may_be an essential precursor