WO1998017585A1

WO1998017585A1 - Hydrodynamic induction bow foil plane oil skimmers

Info

Publication number: WO1998017585A1
Application number: PCT/US1997/019076
Authority: WO
Inventors: George W. Adams
Original assignee: Adams George W
Priority date: 1996-10-21
Filing date: 1997-10-21
Publication date: 1998-04-30
Also published as: AU5085098A

Abstract

A hydrodynamic induction bow foil submersion plane skimmer (50) includes a pair of hull-like pontoons (52, 54) terminating in upper deck-like portions (56, 58). The pontoons (52, 54) terminate at narrowed bow portions (64, 66). The forward bow portions of pontoon decks (56 and 58) are nearly planar with a bow deck (68) which is slightly inclined from bow to aft. Skimmed oil rises through slot-like openings (82) in upper deck baffles (68) and then flows forward over floating weirs (84 and 86) into a collection tank (88).

Description

HYDRODYNAMIC INDUCTION BOW FOIL _SOBM^τn or _{aNE 0IL} ^^

TECHNICAL FTFT.n

This inventⁱon relates to HYDRODYNAMIC INDUCTION HOW _F0Ir SUBMERSION PLANE OIL SKIMMERS. More particularly, _it relate " ⁱmprovements ⁱn oⁱl skimmers disclosed in United States Paten Nos 3,715,034 and 5.194.164 which are incorporated herein reference. *

O 98/17585

BACKGROUND ART

This invention comprises improvements in the cil skimmers disclosed n United States Patent :!o . 3,715,034, Issued: Feb_¬ ruary 6, 1973 to A. I anc f entitled DEVICE FOR REMOVING OIL SLICKS and United States Patent No. 5,194,164, Issued: March 16, 1993 to George ^". Adams. According to the above-identified Ivanof patent "oil floating on a body of water is collected bv moving a sh llow-draft water craft, such as a barge, having sternwarcly slanted bcw section and belew -he water l ne ar. ingress opening in or near the bcw section through an oil slick. The slant of the bow section forces o l m ts path downward!-/ thereby causing the o l, possibly intermingled with water, to flow as a flat layer along tne bottom cf the barge. As the oil reaches the ingress opening t is propelled i to a hold of the barge due to the pressure differential between the c tside and the inside of the barge. Oil thus accumulating in a held of the barge may be removed therefrom from time to time and clear water as may also enter the hold is returned to the body of water."

The effectiveness of skimmers, according to the abcve-iden-

.e er surraoe increases. - r.is is cue to tne cow wave craa—ec by the inclined-plane which tends to collect o l in front cf the bow wave and to reduce the velocity cf the o l relative to tne surface cf the incl ed—cl to the ocmt where he o l does r.o — co down t for collection.

I discovered tna«t o-v.^< t-css.».+t-ι•.on„ι..ng a transverse bodv anead _«* —a Dow, _Λater surface ir.r_^ ... -_, - . ,, ^* °- ^l"^ιa-= s c ceicw zne surface o- --. water a surface wave mav •_* r--.=,--.-... ~ ^v""² _y ^ c^heated wmcn is out of chase w_i-_h -« .«--:.« wave e ted _by -_B. _{lacllne≤-pll},_{s and d}.;._r__c__lv^ -.-.«..-..., ...., ... This .oc., _{can i o} „..„„ .,__ -' ^it at tne forward surface o- -_he ,-,~ι, • ,

----- - .he ^lnclmεc-plane. The sinus les_t . .- .--c_e=. ..._eae ._c^. _{S ls a cyIl}._≤erf __{nβ aχιs of wn} is genera../ oarallel -- --- , ,-, ^e "^ -- - -^--l-ⁱ- tti ocdv. Tne --_c--- i--1<------i-r-..~g bκ~cd-*„v rna / c-=> eκ^tencec rearwarc.v towarc -_ne v ^Λ,_a ^α—___. =«u__..-._*.-.-.a_,_, o~c~,w„ mter-_^ce = -«c may be ex^tended upwardly m wmglets at _tne ou_ter edges _tne^ The wmgle^ts also e.tenc inwardly to guide oil „ _{ZΛ t ιnc}i _ed- Plane wnⁱcn would o^tnerwise be pushed aside oy tne bow wave Tnⁱs ⁱmprovemen^t wnⁱch I call _cnβ nydrcdynamic induc_tion bow -'o- ⁱs dⁱscloseα m tne accve-identified United S_ta_tes Paten_t __!o. 5 , 13-. , - = 4.

Such a submersion plane skimmer employing my hydrodynamic induction bow foil is shewn in Figures 1 through 3 and is manu_¬ factured by Webster 3arr.es, Inc. of 13*. McKinley Street, Roway- ton, Connecticut 06853.

As shown in Figures 1 through 3, the body of the skimmer 20 is a barge-like shape with an inclined submersion plane 22 at the bow 24. The separation tank 26 in the center of skimmer 20 has two horizontal layers of baffles or separation decks 28,30 and is open to the sea through a perforated bottom 32. At the forward end of the separation tank 26 is a collection basin or hold 28 where a discharge pump 34 is located. The skimmer body 20 is supported on eacn side by pontoons 36,38 which are detachable for transport. As the skimmer 20 advances, oil 40 and surface water 42 are gently deflected downward by the hydrodynamic induction bow foil 44. The mixture descends along the submersion plane 22 to a scoop 46 that directs the oil, and a thin layer of water, into the separation tank 26. As the mixture slews down, the oil floats upward and the water flows downward and cut through the perforated bottom 32. A weak flow at the surface cf the separation tank rr.oves the separated oil forward ever floating weir 43 to the collection basin 23 and discharge pump (net shewn) .

Several problems have been encountered m operating the skimmer 20. The hydrodynamic induction bow foil ideally should remain at a preset distance below the surface to maximize the reduction in the bow wave. However, trim of the skimmer 20 was found tc change, going bow down with increasing collection s s≡ά . The skimmer 20 tends to pitch in rough water. These effects increased turbulence at the inlet scoop S reducing ccilectio efficiency.

Some turbulence was noted starting between the trailing edge cf the foil 44 and the nearest portion of the submersion plane 22 and seme was induced at high collection speeds by the foil -H itself.

Additional turbulence was induced at the inlet 43 between the scoop 46 and the bottom cf the submersion plane 22.

The placement cf a pump over the collection basin 29 was awkward because cf the self-adjusting weir 43. When placed ever _.

_the collec_tion basin 23 or, even worse, en the forward deck 51, _the added weight and high center of mass m. reased the ereviouslv

Ideally, _the oil slick should move smoothly down ^the submer^¬ sion plane, _through _the inlet 43, and into the separa^tion tank 26 wi_thout ar.v induced turbulence.

DISCLOSURE OF THE INVENTION

I have discovered that greatly improved r. may b :ee aacchhiieevveedd bbvv: on-turbulent 'low transi^tion , viewed from ^p-^l _J ^ne' ^wh*n substan^tial

ⁱⁿ formⁱng ^the

-._«,, , =^C,cp ... fc₌ substan_t^aM_v coaxⁱal wⁱth said convex portion_; ' hinging _z e aft en ^•d o^u.f ss_aaiic- s_ec~o~o'o so th-- _≤--.-^ ,-,--_.-,.; may be =-ιe- bv «₅,-.ι ._-,_♦. ■ , ^" o^penⁱng ^{y selec}tⁱveiy positioning said scooo- cambering rhe foil_; -^<-¹--''

be fastened thereto, as - s. aΛed .

OBJECTS OF THE INVENTION

It is therefore an object of the invention to improve in- clinec-piane cil skimmers.

Another object of the invention is to increase the velocity with which such o l skimmers may operate effectively.

A furtner cb;ect cf the invention is to decrease turbulence in the collection cf an cil slick by such skimmers.

More specific o ^ ec s cf the invention are: to decrease turbulence caused by a hydrodynamic inductien bcw foil m such a skimmer; to decrease turbulence caused by the presence cf said bow foil adjacent the inclined plane; to decrease turbulence induced at tne inlet of an oil slick into such skimmer; to decrease turbulence caused by velocity dependent trim effects; and to decrease turbulence caused by wave induced pitching cf such skimmers .

Other objects of the invention will in part be obvious and will i part appear hereinafter.

The invention accordingly comprises the features cf construction, combinations cf elements, and arrangements cf parts nioh '. ll ce exempli ied 1.1 the constructions neremafter set forth.

The scooe cf t e invention will be indicated m tne claims.

O 98/17585

3RIEF DESCRIPTION CF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention, reference snould be had to the following de_tailed description, taken m connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view of an oil skimmer according to the prior art lasned tc a tender therefore;

FIGURE 2 is a diagrammatic top view cf tne pr cr art skimmer of Figure 1;

FIGURE 3 is a diagrammatic side view cf tne prior art skimmer cf Figure 1 ;

FIGURE 4 is a perspective view of a hydrodynamic induction bow foil submersion plane oil skimmer according to my present invention;

FIGURE 5 is a diagrammatic plan view of the skimmer cf Figure 4 ;

FIGURES 6, 7, and 8 are diagrammatic side views of the skimmer cf Figure 5;

FIGURES 9, 10, and 11 are diagrammatic side views cf tne separation d=cκs and oettom cf tne o l skimmer of Figure 4 ,-

FIGURE 12 is a diagrammatic cross-sectional view, partially cut away, takes along tne line 12-12 of Figure 7;

FIGURE 13 is a diagrammatic side view, partially cut away, cf tne bow of one cf the pontoons of the skimmer cf Figure ;

FIGURE 14 s a cross-sectional view taxen ong tne line 14-14 cf Figure 1 ;

FIGURE 15 is a crcss-≤ecticnal view similar to Figure 14 showing how differing boc connectors may be εfixed tc tne shimmer cf Figure 4; and,

FIGURE 15 is a diagrammatic cross-sect cnal view, part: cut away, showing now the scoop opening may be varied.

The same reference characters refer tc the same ele~ througnout tne several views of the drawings.

BEST MODE FOR CARRYIMP. _{0ϋτ TKΞ I;iVg ;} ._rΛ.

Now referring

^{■ t}o Fⁱgure 4, a hydrodynamic induc_tion b suomersion :!s". ow foil s ;..dcimmeerr 5500,, according _t isent comprises a pair cf null-lι e- ⁱnvention,

..< pontoons 52,54 terminating deck- ike portions 56.53. .<?₊•_< g in upper

³⁰,³3. Stern portion 60 may also be a sealed compartment termir.ati.i- portion 62,

The pon^toons 52,54 terminate at r.arr_; _τm„_ae _--_-^,r-.._J^a-r-.„c- buo„w. c s ^cw Portⁱons 64,66,

.or-tie- _, o.- p.p-o,o-,,nn,t₊t.o.o-,oo_nn_ ^{ϊwec b} dceecc..--::,s ,5₀5 _βa_rn._cd _D5_ύ3 _aa_rr_{e; nearL} pⁱ.anr.er ^•«::.-. a oow e* 53 wnich <s s'.,.-!.. , - ._ -

-s ^s..g^».. inclined rrom bcw _to ^ar^t ever an ⁱnclⁱned submersion plane 70 ₍see F_igure 6₎. Attacnme.it means 7"> 7₄ -r - -, ,

' ' ' ^,0' ^a-ⁿ-c 73 are provided for launcnmg ana removing tne skimmer 50 frem _tne wa_te.r .

^?he upper separation decx or baffles SO mav oe seen 1 Figure 1. Oⁱl comes up ^tnrougn the slot-like open_ings 82 there_in durⁱng skⁱmmⁱng operations. The oil, on top cf any wa_ter tha_t may have been collec^ted flows forward over floa_ting we_irs 34 and 36 ⁽only cr.e cf whⁱcn ⁱs shewn m Figure -) into a small o_il coi- lecticn tank or no id 33.

A pump ⁽no^t s own 1.1 Figure -) may oe loca_ted w_ith_in and aoove ^t e center cf t e collection _tar._Λ for remov_ing _tna o_il ^tnεrefro ^to a work ecat wit.i the s.<ι mer 50 ₁._{1 t}ew.

An arm 90 s prcvⁱced for adjusting _t e scooo ₍no_t sncwn ₁.₁ - --a ' ' '

Now referring to Figures 5, ό, a: ■ , ■.r.- ≤.ιm er rav ce

; ^" ~ ^"- - -"^" - ^aDOU- ^"* u=?er peripnery tnereof.

The pump s4 (as cast seen -1.--> .r_,.,-..^„,,.-=- _ z _\) _1B en_terec in _tne c l collec^tion .-.old 33 en chair-like s_tand £9 _(£≤s F_igure 3₎.

-•^"•= weirs o, 33 _:e r.inc 'ec- -=-- 9³5o, oas₀ a- ...-.= zz'.i enc e: secara_t on dec. ΞC. The' .- a-r-e_ -_r-^.., ^ι-_:.-. ,w,i,_.π_ r.oataticr. means 103, 132 a_t their top edges.

The hydred narrⁱc ⁱnduction bow foil 104 is lcca_ted uncer _tne ⁱnclⁱned submersion cow cla.ie 70. -- , - -_ --_*.-,.- - „_,, w_... .ne ^t-a__ιr.g upper surrace 106 thereof r.earl- carallel _to the plane 70.

Plane 70, as seen from the bottom, _terιr.₁.₁— ,- - -_^ve portⁱon 108 then a concave portion 110 and tne- a -<_a*e zon^tal portⁱon 112. A plane portion 114 is loca_ted be_tween con- vex por^tion 103 and concave portion 110.

The oⁱl collectⁱng hold 88 and pump 94 are located ove- _th concave portⁱon 103 ^terminating the immersion plane 70 w_ith the center or mass cf ^tne oil and pump being slign_tlv af_t of concave crtio.i 108 ⁱgu ■irree SS,, iⁱ ccaann bbee ssweenn

_o,lane ≤ ≤mmcoth.lv trans^itions from planar to convex (to planar), _to concave and to planar, mime w^ith tne bottom of separa_tion deck 115. The ow ⁱs fur^tner guⁱded by sccop 113 which is hinged to _the bo_ttom l*₀' The scoop 113 may oe adjusted to several posi_tions as d^"~^' cussed below. "°

Frame memoers 122 support tne immersion plane I _Q and the eck 63

The forward wall 122 and rear wall 124 of _the oil collect_ion hold 88 are shown Figure 7.

I s "S" shaped ootto is generally indica_ted at 1 6 and ^structural rⁱos at 123. The corners 130,132 may be seen m F_ig- ures 5 and 3

Fⁱgures 99,. 1¹ n0, a-n^d 1i _'1 s_h,ew tne upper and. .lows separation decks 80,116 and ^the bottom 120, respectively. Each _is oerfo- ra^ted cy ^transverse cnanneis indicated at 124 m deck S 0 , i 36 m deck 115, and 1 -2-3- .-.-. ~_rc-...,^,Γ_Λ _ * -_,:_*0. .>..c„te t at t ese vary n size

--^<-.. ^r... _n CSCΛ. OO .-.c :lo anc co_ttcm 120.

Fⁱgure 12 ⁱs a partial representative cross-sec_ticn snewmg ^tne pon^toon 52 _; decks 30,116 and oottom 120. The pon_toon 52 comprⁱses a vertical

s-.-cimmer _tc wr.icn are mounted decks 3 ^V- 0^J,-"-¹

uooer ver_tical wall 142 terminates ---- --_*--se

-.,■-• c-- aoout tne wa_ter line. lower iacc„.^.aa'_. ■^,. = -.ιi i -,^ •₀ - _te.,r,min„a.te-s at ≤_traicn_t oo_ttom section 143.

Varicus cro -s-ⁱs.. r..r≤^cr.-._'.hλec_-bς I[,-.^,-j,-. s-n•_,o„,w._n>) =_.r„e_ ,u,sec- _to ^e"*_cπ^, _""" ^sη ---> pontoon 52. Pon^toon 54 is tne mirror image of pon_toon 52.^"'"

Vertⁱcal ⁱnner side wall 140 of forward pon_toon 54 _is ex_¬ tended forward a^t 152 m front of skimmer 50 (see F_igures 13-15 and 6⁾. Diagonal side wall 154 is welded _to wall 140 as sncwn. Ex^tended por^tion 152 has holes 155 _ther-_i -_or ^ _Λ - . bolts 156 for affixmc d< '_** * „ • -aceⁱvⁱng

- c-^β-ⁱng coom connecters 153 aid _isn tneretc when booms a--» _-_ac?3ιⁱ-o,y,e.dj as shown Figure 1. ⁱ⁵⁰

- = -_r.ι.._ _o .-ⁱgure 16, sccoo 113 is hinc=d _*-- •-_,

120 at -_ce 15~ ^,..-..; '-^J-ⁱg-α _.„ ccttom

..-..g^« lo-. _Λ._{j a}._{iag arm 90 is llL}„ _{sh r»t}a ^ about oivot 154 ^τιf_< ι _S ;. . ^*vl-^ates

--1-. -o3 m arm 9, ceoperate with holes 170 and a removable bolt

⁽not sncwn, to allow positioning scoop 113 _{in cne of a} „„„_., '] positions as rac *uired bv- --'^•i^•s^{e r} _π"-=_*t-,u,r-e_^ cr- f ^"* collection. —_^ c^c- i- ^sc?¹i-iil a=.-c,: s-oeed of

One of several c-=~*--s u_V(-ι,_^,. e.<cl_uslo.ι cars 163 can also be seen _in

: lσu

I have tested a camoered ^oii : -i t , ^α -^{oli iD} wnicn was a NACA 5517 =>nd ⁱt reduced turbulence due to t_h«» _f-ii , o ^tne r^υii itsel: significantly over my uncambered orior a-- _{01 D1},

-.o^ils. Placing the trailing surface of tne roil substantia -l-l-y t-arrs^ei^J.!lβeii _*t.,o-, tne immersion plane 70, re- ducec turbulence induced -=l^loonncg tnn.e. pιlane -/„0 c-ue to the orr=esence or the foil 104. However, : believe

'e a thinner cambered foil such as NACA 5512 would fur_th;

»er reduce turbulence due to the foil itself. NACA 5617 has a thick: ess to cord ratio cf 17% while

^{5≤£ "D cord} ---- cf 12%. sct.i of t ese -°- -² ~ave tneir _. ^*oomt o-

c„a-..,e•„er cenmd the cen_ter of

^*"^'"^{Cs 5e"}^ ^t vιty to angle of a_ttack.

. _t j . cambered foil, properly contieureα, has strong advantages over the uncambered lifting surface. Among othe things- ^• At the same lⁱft coefficⁱents, it results in more gradual stall (that s, it shifts the stall rearward) durⁱng severe attack angle variations resulting from pitching of the entire un_it o uri f irioumiii i ww naavvveeuss.. ^β

At the same lift coefficients and thickness ratios, it allows the leading edge of the foil to be lower relatⁱve to the water surface, thus intersecting a larger vertical portion of the incoming flow stream.

A . t _Λ the same li .s ,t coefficien _Λts it allow , s t ^ιhⁿe^e fa ^I0i^Ul t ^tr^o» κ«^e

whi-ch L. red Juces th ■ e f _*•orward buoyancy problem, and reduces turbulence

It allows the lift distributⁱon, and hence the resulting water surface, to be more " r ¹⁰ , requirements-for example, to cause a smooth transition locally at the waterhne ⁱntersectⁱon with the inclined plane, avoiding local mixing of the oil and water. ^σ "

It allows the traⁱling edge of the foil to be better geometrically aligned w_ith the inclined plane whⁱle preservmg the low attack angle of the foil at the leading edge

It allows the foⁱl to more closely conform to the prevailing flow field, reducing the necessⁱty for abrupt flow transitions particularly at the trailing region be most effecuve m these applications, the camber should be unusually large and the atⁱon ofthe camber should be unusually far aft. ^*»" "^»=

z4&t~Α-l5L e£≠+ , ~ £i-fέJ øL&rø _ ,_

_<^ ^.^^

__^^^- ii^4^^_t-

Each cf the above described features add to the efficiency and speed of collection. Ai but t.-.a multiple boom connectors comparatively decrease tne turbulence cf tne flow cf cil and water into tne s.iimmar to minimize r. xir.g cf o l and water and allowing t e cil siicx tc flow smootn y ir.der tr.2 middle collec

More speci ically , the taper cf t.-.= pontoons c≤lcv the wate line reduces pitching and variation n tr m cue tc speed. Placement cf the cil collection held a d pump over tne inlet and low dcv/n also reduces pitching and tr m variation due to speed. Use of a rear cambered foil (one with the maximum camsar cehir.d the mid point of the ccrd) allows fine adjustment of the angle cf attack of the foil to minimize turbulence and greatly decreases turbulence caused by an le of attack variation ue tc pitching or skimmer trim variation. The smoothly varying terminating portion cf immersion plane beginning below the bottom of lowest separation deck, initially convex, than concave, then piar.ar with the bottom cf the lowest .separation deck and t.-.a coaxial snape of the scoop all direct t a flew of the slick under t.-.a lowest separatio deck w th minimum turoulence. Having the near surface of the foil substantially parallel to the immersion plane minimizes the turbulence due to the interaction between the foil and the immersion plane. The adjustable scoop opening allows the amount of water taken nto the skimmer to be minimized.

Claims

1. :.ι an o l skimmer comprising a hull for floating on a water surface and comprising a bcw, a stern, and a hold wi_thin said hull for containing cil, said bcw comprising an inclined surface extending from above said water surface downwardly and rearwardiy through said water surface toward said stern and ter_¬ minating in an opening into said skimmer, tne improvement com_¬ prising : said inclined surface wne. viewed from under tne skimmer substantially smootnly transitioning at said opening from said bow substantially convex, tnen substantially concave, and then suostantiallv noncon- tal portions; a foil lifting body under said water surface, ahead cf said inclined surface, extending transverse to a canter line cf said skimmer drawn from bcw to stern, and said foil lifting body being cambered; a pair cf hull- like pontoons forming the sides cf said skimmer; sa d pontoons narrowing from aeout tne water line to t e bottom tr.erecf; and said .-.old came located s escar.ciall above said opening; w.iereby ≤moctn increased ncnturbulent flow cf oil and water nto said skimmer is achieved.

2. The shimmer defined in claim 1 and a pump for tumping oil from sa d held located substantially accve said opening m said hold.

3. The skimmer defined ^,° -' claim 1 and a pair cf plates extending forward cf said siea wa.-s comprising means for attaching one of a plurality or differing ocom connectors thereto.

4. The oil skimmer defined in claim 1 and a pair of upstanding floating weirs at either side of the ster wise portion cf said hold.

5. The oil skimmer defined in claim I and a pump for pumping oil from said hold located at least in part between said weirs.

6. The oil skimmer defined in claim 5 wherein said pump is substantially located above said opening.

7. The oil skimmer defined in claim 1 and a pump for pumping oil from said hold substantially located above said opening.

8. The oil skimmer defined in claim 7 wherein said pump is substantially located within said hold.

9. The oil skimmer defined in claim 1 wherein there is a straight portion between said concave and convex portions.

10. The cil s.-i mer defined in claim 1 and a separation deck and wherein said convex portion substantially smoothly transitions the flow cf oil and water along said oiir.ed surface

11. The oil skimmer defined in claim 10 wherein saic in^¬ clined surface is substantially planner.

12. The oil skimmer defined in claim 1 ^•.•.^•herein said in^¬ clined surface is substantially planner.

13. The oil skimmer defined in claim 1 and a hinged bottom scoop located below said convex portion and means for positioning the forward edge thereof in a oluralitv of ocsition≤.

14. The oil skimmer defined in claim 1 wherein said hydro_¬ foil is cambered.

15. The oil shimmer defined claim 1 and a nydrofo l located in front cf said inclined surface.

16. The oil skimmer defined m claim 15 wherein _tne trailing upper surface cf said hydrofoil is generally parallel to the portion cf said inclined surface closest tnereto.

17. The cil skimmer defined in claim 15 wnerein said nydrofoil is cambered.

IS. The oil skimer defined m claim 1 wnerei the trailing upper surface of said foil lifting body is generally parallel to the closest portion of said inclined surface.

19. In an o l skimmer comprising a hull for floating on a water surface and ccmpnsmg a bow, a stern, oil and water separating means, and a noid within said hull for containing oil, said bow comprising an inclined surface extending from aocvε saie water surface dcwnwardly and rearwarcly tnro gn said water ε_r- ace toward said stern and terminating in an opening into sa d skimmer, tne improvement comprising: said neid being located suostantiallv aoove said opening .

20. The oil skimmer defined m claim 5 wnerein: said incimec ≤-rface wnεn viewed from uncar tne s.-i - mer ≤ ostait ally smcotni transitien ng at saic opening from said oow in convex, cr.e.i concave, and t.-.en substantially roritontal ocrtions. ?he oil skimmer defined in claim 20; and, ⁱ foil lifting body under said water surrace, ahead o: said i: .cur surrace, extending transverse tc a cente: ^α-- ^d mer crawn from bcw t: stern, ώanncd sαic foil lifting body beirng cambered.

22. The oil skimmer defined inr cclla;im ^1; and, a pair cf hull-ϋ e pontoons forming the sides of said o-i..^ _m aocut _tne wan. ^tine tc the bcttom thereof.

o l skimmer defined ■ iaim ^"O a paⁱr of hull-like pontoons forming the s_ides of said skimmer; said pontoons narrowing from about the water line to the bcttom thereof.

24. The oⁱl skimmer defined in claim IS; and, a foil lⁱftⁱng bcdy under said water surface, ahead of said ⁱnclined surface, extending _transverse to a cen_ter line of saⁱd skimmer drawn from bow _to stern, and said foil lifting oodv cam- ,-.-.---.__> =

water surface and saⁱd hull fer con surrace ex^tendⁱng *^»». ^« .*..

„ ... _.. „.._c..__r. _i -₀ -_{a α s irn:τ}._er( _ ₃ ___„._„_. prising:

er subs^tantially smoothly _transiticnm sa d opening from said bow in ssu,-bs_<tantiallv convex, then substan^tially cencave, md then suostantiallv hc'ricon- tal cortions.

26. In an oil skimmer comprising a hull for floating on a water surface and comprising a bow, a stern, and a hold within said hull for containing oil, said bow comprising an inclined surface extending from above said water surface dcw wardlv and rearwardiy through said water surface toward said stern and ter_¬ minating in an opening into said skimmer, the improvemen_t com_¬ prising: a foil lifting body under said water surface, ahead of said inclined surface, extending transverse to a center line cf said skimmer drawn from bow to stern, and said foil lifting body being camoerec.

27. In an oil skimmer comprising a hull for floating on a water surface and comprising a bow, a stern, and a hold within said hull for containing oil, said bow comprising an inclined surface extending from above said water surface downwardly and rearwardiy through said water surface toward said stern and terminating in an opening into said skimmer, the improvement ccm- pris g: a pair of hull-like pontoons forming tne sides cf said skimmer,- sa d pontoons narrowing from move tr.e water line to tne bottom tner≤of.

23. I an oil ≤ m er comprising a null for floating en a water surface and comprising a bcw, a stern, and a hold withi said hull for containing oil, said bow comprising an inclined surface extending frcm above said water surface downwardly =-nd rearwardiy through said water surface toward said stern and terminating an opening into said skimmer and a pair of generally verticle side walls extending acove and belcw the water l ne, tne improvement comprising: a pair of plates extending forward of sa d side walls comprising means for attac.iing one cf a plurality of differing bccm connecters tnerεto.