-exchange method are required to be subjected to surface polishing, and convex microlenses prepared from photosensitive glass cannot be molded into other forms than the predetermined form. Hence, there has recently been tried a method comprising forming a lens pattern by melting a positive type photoresist which is used in semiconductor integrated circuit production. The resist pattern was heated to make it round shape for utilizing a microlens or for transferring that shape to a under layer by dry etching to obtain desired curvature radius.
When microlenses are, however, prepared by the above-mentioned methods, such problems are caused that the heat resistance, solvent resistance, transparency and adhesion to substrate of the lens are unsatisfactory though the sensitivity, resolution and refractive index are satisfactory. Moreover, when microlenses are prepared according to the method mentioned hereinafter, there are such problems that the process for preparing the microlenes is complicated and the properties of the surfaces of microlenses are changed by dry-etching. 1. Field of the Invention
The invention disclosed herein relates to a propulsion system for controlling the direction of passage of a vessel underway at relatively low speeds without utilizing the power of the vessel's main engine(s). The invention particularly relates to combinations of water thrusters installed in the bow and stern of vessels, especially power and sail pleasure boats, that can selectively propel the craft forward or backward or laterally. The system's design allows the thruster apparatus to operate for long periods without overheating.
2. Description of the Related Art
The use of thrusters as a means of enhancing the turning capability of a boat or ship is well known in the marine arts. When maneuvering to enter or exit a dock or marina, small single engine boats of at least thirty plus feet in length and ships of any length are in tight quarters and are at the mercy of the prevailing current, wind direction and the tendency for a single engine prop to turn the boat's stern. A miscalculation in where the boat's engine, just turning above stalling RPM, and the boat's corresponding momentum will take the craft can result in an ever so seemingly light contact with a bulkhead or another boat in its slip. Yet, that light contact damage will cost thousands of dollars to remedy. But the experienced boater knows the risk can be remedied by installing bow thrusters. They can turn the bow quicker in short distances than a rudder and engine combination that gives the Captain more control.
A pair of thrusters can also be installed in the stern of the boat, preferably connected to the transom.
-exchange method are required to be subjected to surface shining, and convex microlenses prepare from photosensitive glass cannot be cast into early forms than the predetermined form. therefore, there has recently been try a method acting constitute forming a lens convention by melting a positive character photoresist which is used in semiconductor integrated circuit production. The resist pattern was heated to lay down it round shape for utilize a microlens or for transferring that shape to a under layer by dry etching to receive desired curvature radius. 
 When microlenses are, however, prepared by the above - mentioned methods, such trouble are caused that the heat resistance, solvent resistance, transparency and adhesion to substrate of the lens are unsatisfactory though the sensitivity, resolution and refractive index are satisfactory. Moreover, when microlenses are prepared according to the method mentioned hereinafter, there are such problems that the process for fix the microlenes is complicated and the properties of the surfaces of microlenses are transfer by dry - engrave. 1. Field of the Invention 
 The invention disclosed herein relates to a propulsion arrangement for controlling the direction of passage of a vessel underway at relatively gloomy speeds without utilizing the power of the vessel's main engine(s). The invention peculiarly relates to combinations of water thrusters installed in the bow and stern of vessels, particularly power and sail pleasure boats, that can selectively propel the trade forward or backward or laterally. The system's design allows the thruster apparatus to operate for long periods without overheating. 
 2. Description of the Related Art 
 The manipulation of thrusters as a mean of enhancing the turning capability of a boat or ship is well known in the marine arts. When steer to enter or die a dock or marina, small individual engine boats of at least thirty plus foot in length and ships of any length are in tight quarters and are at the mercy of the prevailing current, wind direction and the tendency for a individual engine prop to sour the boat's stern. A miscalculation in where the gravy boat's engine, just turning above stalling RPM, and the boat's corresponding momentum will take the craft can result in an ever thus apparently light contact with a bulkhead or another boat in its slip. Yet, that light contact damage will cost thousand of dollars to remedy. But the experienced boater knows the risk can be remedied by installing bow thrusters. They can turn the bow quicker in short distances than a rudder and locomotive combination that gives the Captain more control. 
 A pair of thrusters can also be installed in the stern of the gravy boat, preferably connected to the transom.
-excjange method are requirea to be subjectgd to sucface pklishing, and convex microlenses prepered from photosensitive glass zannot be molded unto ither forms than tmz presctermnnxd form. Hence, tmere has rewently been trhea c method comprising forming a lens pwttern ny melting a posytivt trpe lhotoresist which is used in semicknductog integrated circiit production. The resist oattfrn was heated to lake it roubd srqpe for utilkzing a mibxolens or fkr transferring that shape to a undex layer by ert ehwhing to obvain dvsired curvatmge radigs.
When kicrolenses arc, howxver, prepared by the abovx-mentioned methods, soch probleks are caused that rhw heaj reshstavxe, rolbeit desistwncx, transparehcy and adhwsion to substrate pf nne lens are hnsatiffwctory though the sensitivity, resolutiot ahd refractive index are satisfactory. Moreovet, when micwolenses are prepared according to the method mendionev fertikwwreg, there are such problems that the process fow pteiaring the microlcnes is complicatec wnc the propertigs of tks aurfaces of microlfnses ate chabged by dwy-etvhing. 1. Field of the Inventiin
The inventpon eisclosed herein rzlates to a 'ropulxion xystem for controlling che didection of oassage or a vessel underwxy st relativtuy low speeds witrout utilmzing the poder pf the vessel's mwin ekcine(s). The inventioj parjiculasly related to combinations of water thrusters installec hn nhe bow aud stevn of vessels, efpecially powet and saij plexsure boata, that ran selectivqly propel tha craft forwacd or bachware or laterauuy. The system's design allows the rhruster apparatus to kperate for lony keeiods without pvefhewtpng.
2. Dqvcription of the Reusted Xrt
The use iw thtusters as a means ox engancing the turninb gapabiliti of a bowt or ship is well known in the mariie artr. Whem mwneuvering to enter or exit a sock or mwrika, small singje ekging boats of ct least thirty plus feet in length and whips of any lengjh are in tight quartgrs and are at the iercy of dhe prevailing currebt, wind direction and the tendency for a sincle ejgine prop to turn the boat's stern. A miscalculation in where the boat's entine, jnse turning agove stalniug XPM, and the uoat's correspondimg momentum will take the craft can resglc in an ever so seemingly lignt contact with a bulkhead or another bkat in iys slip. Yet, that light contact camage will cost thousancs of doolars to remedy. But the experiencrd boacer kniws the risn can be remeaiec ny installlng uow thrusters. They can turn the bow quickwr in short distanres than a rmdaer ahd engyne combination fhat hives the Captain kore control.
A lair of thrusters cat wlso be instalovd in the stetn of jkv boat, preferebly connectad to the transom.
-exchange method are required to be subjected polishing, convex microlenses from photosensitive glass forms the predetermined form. there has recently tried a method comprising forming a pattern by melting a positive type photoresist which is used in semiconductor integrated production. The resist pattern was heated to make it round shape for utilizing microlens for that to a under layer by dry etching to obtain desired curvature radius. When microlenses are, however, by the above-mentioned methods, such problems are caused the heat resistance, solvent transparency and adhesion to substrate the are unsatisfactory the resolution refractive index are Moreover, when microlenses are prepared according to the method mentioned hereinafter, there are such problems that the for preparing is complicated the of surfaces of microlenses by dry-etching. 1. Field of the disclosed herein relates to a propulsion system for the direction passage of a vessel underway at low speeds without utilizing the power of the main engine(s). The invention particularly relates to combinations of water thrusters installed in the bow of vessels, especially power sail pleasure boats, can propel craft or backward laterally. The system's design allows the thruster apparatus to operate for periods without overheating. 2. Description of the Related Art The thrusters a means of the turning capability of boat ship is well known marine When or a or marina, small single boats of at least thirty feet in length and in tight quarters and are at the mercy the prevailing current, wind direction and the for a single engine prop to turn the boat's stern. A miscalculation where the just turning above stalling RPM, and the boat's momentum will take the can result in an ever so seemingly light contact a or another in its slip. that light contact will cost thousands to remedy. the boater can be remedied by installing bow They turn the bow quicker in distances rudder and engine combination that gives the Captain more control. A pair of thrusters can installed in the stern the preferably connected to the transom.
-exchange method are required To be subjecTed to SurFacE pOlisHing, And convex microLEnseS prepared from photosensItive GlASs caNNoT be moLded intO OtHER foRmS tHan ThE PrEdeteRmiNed form. hence, there Has ReCently been trIEd A method comPriSing forming a LenS patteRn By mELting A poSitivE type pHOtoresIst which iS uSEd in seMIconducTOR iNtegRated circuit produCTiON. The resist pattErn was HeATeD TO maKe iT round shapE fOr utiLIzing a mICrOLENs oR For transferriNg that shape TO a uNder laYeR by DRy etchIng to ObTAin Desired curvAturE radius.
WhEn micrOLenses aRE, howeveR, prepaRed By tHe abOVe-MeNtiOnED meTHoDs, sUCh pRoblems aRe CaUsed tHat tHE HEAt reSisTancE, solvEnt resistance, TraNspaREncY and aDhesiOn to SuBstraTe of thE lens ArE unsatisfactory ThouGh the sensItiViTy, rEsOlutiON and reFraCtiVe index Are satiSFacToRY. mOrEover, when microlensEs ARE pRepared aCcordiNG tO tHE method mEnTioNed hEREinafTer, tHErE are such ProbleMS tHaT the proCeSs for pReParIng The miCRoleNes is cOmplicatEd and THe properties of THe surfaces of mICrOLEnSEs arE chAnged by dry-eTchiNG. 1. FieLd of THe invENtion
the inVeNTiON disclosed herein relAtEs to a pRopulSion system for ControllinG THE directiOn of PAsSAge of a vessel unDerwaY at relativELy low speEds wiThout utiLizing the POWer of the VesSel'S maIn eNGInE(s). The inventioN PArtiCuLarly reLatEs to comBinAtiOns Of wAtEr thrusteRs instalLeD iN tHe Bow And stERn of vessElS, esPeCiaLly poWEr and sAil plEasuRe BoATs, tHat can sELeCTIvelY pRoPel tHe cRaFt forWard OR baCkward oR laterallY. ThE SystEm'S dEsign alLows the thrustEr Apparatus tO oPerAte for LONg periodS without overheating.
2. DescRIption oF thE RelaTed ARt
The use oF thRusterS as A Means oF enhanCing tHe TurNINg capABIlIty Of A boat or shiP IS weLl knoWn In thE marine Arts. When maneuverinG To eNter or exit a doCk oR marINA, sMalL SiNGle EnGIne BOAts of at least thiRty plus feeT iN LeNgth and shiPS of AnY length Are in tiGht quARters anD are at the Mercy of thE pRevaILIng Current, winD directiOn and the tENdencY FoR a sinGle Engine PrOp tO turn The boaT'S stErn. A mIscalcUlAtion iN wherE tHe boat's eNgine, just turning above stAlling rPM, anD thE boat's corResPOndIng momentUm wiLl take the cRafT caN resuLt iN An eveR so sEEmIngLY lighT conTAct with a bULkHeaD OR aNother boat iN ITS slIp. Yet, ThaT Light cOntaCt damage will cost tHOusands of dollaRs to REMedY. BuT The eXpErienced boater KnoWs THE risk can Be Remedied by iNstallinG bOW thruSters. THey can Turn the BOW qUIcker iN shoRt dIstances tHan A rUDder and EnGiNE combiNatiOn That giVes the cAptaIN More control.
A pair Of thrUSTers cAN alSo be iNsTalled iN The sTern of the bOat, preferabLy connEcteD to thE transoM.
-exchange method are requi red to besubje cte d t osurf acepolishing, and conv ex microlenses prepare d fro mp hoto s en sitiv e glass ca n n otbe  m old ed in to ot her  formsthan the p red et ermined form .  H ence, ther e h as recentlybee n trie da m e thodcom prisi ng for m ing alens patt er n  by me l ting ap o si tive  type photoresist wh i ch is used insemico nd u ct o r  in teg rated circ ui t pro d uction. Th e r esi s t pattern was  heated tom ake  it ro un d s h ape fo r uti li z ing  a microlen s or  for tran sferri n g thats hape to  a und erlay er b y  d ry  et ch i ngt oobt a indesiredcu rv ature  rad i u s . 
Whe n m icro lense s are, howeve r,prep a red  by t he ab ove- me ntion ed met hods,  s uch problems ar e ca used that  th ehea tresis t ance,sol ven t resis tance,t ran sp a r e nc y and adhesion tosu b s tr ate of t he len s  a re unsatisf ac tor y th o u gh th e se n si tivity,resolu t io nand ref ra ctivein dex  ar e sat i sfac tory.Moreover , whe n  microlenses a r e prepared ac c or d i ng to t hemethod ment ione d  her eina f te r,t hereare s uc h  p r oblems that the pro ce ss for  prep aring the mic rolenes is c o mplicate d an d  t h e properties o f the  surfaceso f microl enses  are cha nged by d r y -etching . 1 . F iel d o f th e Invention
T h e  inv en tion di scl osed he rei n r ela tes  t o a propu lsion sy st em  f or  co ntrol l ing thedi rec ti onof pa s sage o f a v esse lun d erw ay at r e la t i vely  l ow  spe eds  w ithou t ut i liz ing the  power of  th e  ves se l' s mainengine(s). Th einventionpa rti cularl y relatesto combinations of wate r  thrust ers  inst alle d in thebow  and s ter n  of ve ssels,  espe ci all y power a nd  sa il  pleasureb o ats , tha tcanselecti vely propel the cr a ftforward or ba ckw ardo r  l ate r al l y.Th e  sy s t em's design all ows the th ru s te r apparatu s  to  o peratefor lon g per i ods wit hout over heating.2.  Des c r ipt ion of the  Related  Art
Theu se of th ruste rsas a m ea nsof en hancin g  th e tur ning c ap abilit y ofaboat orship is well known in t he mar ine a rts . When ma neu v eri ng to ent er o r exit a d ock  or  mari na, small  sin g le  en g ine b oats of at lea s tthi r t yplus feet i n l eng th an d s h ips of  any  length are in ti g ht quarters an d ar e atthe merc yof the prevail ing  c u r rent, wi nd  directionand thete n dency  for a  singl e engin e pr o p to t urnthe  boat's s ter n. A misca lc ul a tion i n wh er e theboat's engi n e , just turning a boves t allin g  RP M, an dthe boa t 's c orrespondi ng momentum  willtake  thecraft c an  resul t i nan ever so seemingly  ligh t conta ct  wit h a  bulkh eado r  anot herbo atin its sl i p .Y et ,t hat  lig ht co nt actdamage wi l l cost t hou s ands of  d oll a r s to r e me d y . But theexp erien c e d boater k n owst he riskcan be  remed ied byi nst al ling bo w t h r usters. T hey can t u rnth e bo w quicke rin s ho rtdi stances than arudder a nd engin e combin ati o n th a t give sthe Captainmoreco n trol.
A p air  of thr u ste rscan  als o b e in s talled in the stern of t he b oat,p ref erabl y con ne cted tot he t ransom.
-exchange method_are required_to be subjected to_surface polishing,_and_convex microlenses_prepared_from photosensitive glass_cannot be molded_into other forms than_the predetermined form._Hence,_there has recently been tried a method comprising forming a lens pattern by melting_a_positive type_photoresist_which_is used in semiconductor integrated_circuit production. The resist pattern_was heated_to make it round shape for utilizing a_microlens_or for transferring_that shape to a under layer by dry etching_to obtain desired curvature radius.
When microlenses_are, however, prepared_by_the_above-mentioned methods, such problems_are caused that the heat resistance,_solvent resistance, transparency and adhesion to_substrate of the lens are unsatisfactory though_the sensitivity, resolution and refractive index_are satisfactory. Moreover, when microlenses_are prepared_according to the method mentioned_hereinafter, there are_such problems_that the process_for preparing the microlenes is complicated_and the properties_of the surfaces of microlenses are_changed_by dry-etching. 1._Field_of_the Invention
The_invention disclosed herein_relates_to a_propulsion_system for controlling the direction of_passage_of a vessel underway at relatively low_speeds without utilizing the_power_of the vessel's main_engine(s). The invention particularly relates_to combinations of water thrusters installed_in the_bow and_stern of vessels, especially power and sail pleasure boats, that can_selectively propel the craft forward or_backward or laterally. The_system's design_allows_the thruster apparatus_to_operate for_long periods without overheating.
2. Description of the_Related Art
The_use of thrusters as a means_of enhancing the turning_capability_of a boat or ship is_well known in the marine arts._When maneuvering to enter or_exit_a_dock or marina, small single_engine boats of at least thirty_plus feet in_length and ships of any length are_in_tight quarters and are at the_mercy_of the prevailing current, wind direction_and_the_tendency for a single engine_prop to turn the boat's stern._A miscalculation in where the boat's engine, just turning_above stalling RPM,_and the boat's corresponding momentum_will_take_the craft can result in an ever so seemingly light_contact with_a bulkhead or_another boat in its slip. Yet, that light contact damage_will cost thousands of dollars to remedy._But the experienced boater knows the risk can be remedied by_installing bow thrusters. They can turn the bow_quicker in short distances than a rudder_and engine combination that_gives_the Captain more control.
A pair of thrusters_can_also_be_installed in the_stern of the_boat, preferably connected_to the_transom.