United States Patent 1191 [111 3,902,554 Hooper [45] Sept. 2, 1975

[54] BLOWOUT PREVENTER GUIDE 3,817,412 6/1974 , Mercieret al. .................. .. 114/.5 D

$223411!“ FOR OFF-SHORE DRILLING OTHER PUBLICATIONS SEDCO 702-First of the New Series, Donald M. Tay

[75] Inventor: galvifd William Hooper, La Habra, 10f; Ocean Int/Mm,’ May 1973, p_ 29. a1 . .

[73] Assignee: Global Marine Inc., Los Angeles, Primary Examiner —F1'ank L- Abbott Calif’ Assistant Examiner—Richard E. F avreau

Art ,A t, F‘ —Ch't',Pk &H1 [22] Filed: Mar- 12, 1974 orney gen 0r zrm rls 1e ar er ae

[21] Appl. No.: 450,362 [57] ABSTRACT

Apparatus for guiding a blowout preventor stack as [52] US. Cl. ..................... .. 166/.5; 175/5; 114/.5 D sembly through the moon pool or drilling well of a [51] Int. Cl.2 .......................................... .. E21B 7/12 drilling ship or semisubmersible platform. Guide [58] Field of Search .......... .. l66/.5, .6; 175/5, 7, 10; 'means rigidly secured to the vessel form a pair of

114/.5 D spaced parallel tracks extending vertically along one side of the moon pool from a point above the deck

[56] References Cited down to or into the water. The blowout preventor as UNlTED STATES PATENTS sembly includes guide elements which engage with the

3,189,093 6/1965 DeVries ............................... .. 166/.5 track when the assembly ‘5 moved ml" posmo“ Over 3 226 72s 12/1965 Walvoord . . . . . . . . . . . .. 166/.5 the mm“ P°°l- The Stack assembly ‘S the“ l°wered

3:333:562 8/1967 Deal et aL 114/5 D down the guide means into the water below the vessel. 3,498,392 3/l970 Knorr . . . . . . . . . . . . . . . . . . . . . .. 175/5 . . .

3,739,736 6/1973 Carreau et al. .................. .. 114/.5 D 10 Claws-114 Drawmg F'gures

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3,902,554 I

BLOWOUT PREVENTER GUIDE ASSEMBLY FOR OFF-SHORE DRILLING VESSEL

FIELD OF THE INVENTION

This invention relates to off-shore drilling vessels, and more particularly, is concerned with means for guiding a blowout preventor stack from the deck of the vessel to the moon pool into the water. -

BACKGROUND OF THE INVENTION

The use of drilling vessels and semisubmersible plat forms which buoyantly support a drilling rig over a sub surface drill site are well known. Conventional practice involves ?rst positioning a base or template which is an chored to the sea floor over the drill site. A blowout preventer stack is then mounted on the platform and connected to the top of the surface casing. A riser ex tends from the top of the blowout preventer stack to the surface through which the drill stern can be lowered into the hole and through which the drilling mud is cir culated back to the surface. As deeper wells with their higher pressures are

drilled, larger blowout preventer stacks have been re quired. Such a stack, for example, may have a bore of over 20 inches, and may stand as high as 40 ft. in height and weigh up to 200 tons. Because of its large size and weight, the maneuvering of the blowout preventer stack from the deck down through the moon pool or drilling well by lowering it on the end of the riser down to the sea ?oor presents a considerable problem, par ticularly on a heaving, rolling vessel. The heavy mass of the blowout preventer stack suspended on the lower end of the riser tends to swing from side to side in re sponse to motions of the ?oating vessel. Obviously if such heavy equipment were to swing against the sides of the moon pool or other surrounding structure or equipment, severe damage could easily result.

It is therefore desirable to provide some arrangement for rigidly constraining the blowout preventer stack while it is being moved into position over the moon pool and lowered into the water beneath the vessel. Once lowered into the water, the damping effect of the water prevents any tendency of the stack to swing back and forth with motion of the vessel, and the blowout preventer stack can be easily constrained by the con ventional guide lines which extend between the vessel and the template. One arrangement for handling the lowering of a

blowout preventer stack is described in the article “SEDCO 702— First of the New Series” in the May 1973 issue of Ocean Industry, page 29. In this arrange ment, the blowout preventer stack is initially stored on a test stump. A bridge crane is used to lift the stack off the stump. A special jig is used to rigidly secure the blowout preventer stack to the bridge frame. The bridge crane moves the stack over the drill hole. The stack is then lowered onto spider beams, the guide lines are attached and the riser pipe is stabbed into the top of the stack. The stack is lifted off the spider beams by means of the riser and drilling rig, the spider beams are spread apart and the stack is lowered into the water. The stack is constrained by guides on either side of the stack which constrain the stack while it is lowered into the water.

SUMMARY OF THE INVENTION

Applicant‘s invention is directed to a method and ap

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2 paratus for transferring the blowout preventer stack from its test stump onto the end of the riser for lower ing the stack through the drill opening into the water. This is accomplished without the need of a bridge crane and a lift frame or jig to‘restrain the stack while it is being lifted and moved by the bridge crane. Applicant’s arrangement also avoids the necessity of lowering the stack onto the vertical guides.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention reference should be made to the accompanying drawings, wherein: FIG. 1 is an elevational view of a first embodiment of

the present invention; FIG. 2 is a plan view of the embodiment of FIG. 1; FIG. 3 is a schematic perspective view of the embodi

ment of FIG. 1; FIGS. 4, 5, and 6 show details of the track and associ

ated mounting structure; FIG. 7 is a side elevational view of the coupling unit; FIG. 8 is a top view of the coupling unit; FIG. 9 is a plan view of an alternative embodiment of

the present invention; FIG. 10 is a front elevational view of the second em

bodiment; FIG. 11 is a side elevational view of the second em~

bodiment of the invention; and FIGS. 12, 13, and 14 show constructional details of

the second embodiment.

Detailed Description

Referring to the embodiment of FIGS. 1 through 8, there is shown a portion of a drilling ship in section, the ship including a main deck 10 and a bottom 12. A dril ling opening or moon pool 1.4 extends vertically be— tween the deck 10 and bottom 12 and is open to the sea, water rising in the moon pool to the indicated water level W/ L. A drilling rig (not shown) is supported over the moon pool 14 by box girders 16 supported at their ends from the deck 1(ll by superstructure (not shown), the box girders 16 spanning the space above the moon pool 14.

Drilling ships for carrying out subsurface drilling for oil are well known. The ship is located over the drill site and anchored. A base or template is then anchored to the ocean floor and a casing is set which terminates at the template. Before deep drilling is commenced, a blowout preventer stack is then mounted on the tem plate and secured to the top of the casing. A riser is at tached to the top of the stack and extends up into the moon pool 14 above the water level. The riser receives the drill string and provides a conduit for return of the drilling mud. The subsurface blowout preventer stack, indicated

generally at 18, is initially mounted on a cart or sled 20 to one side of the moon pool 14 on the deck 10. The sled 20 serves as a test stump for testing of the stack be fore it is lowered to the template on the ocean floor. The sled 20 has a pair of skids, one of which is indi cated at 22, which are spaced.‘ apart sufficiently so that the sled or cart 20 can bridge the moon pool 14, the skids 22 resting on the deck 10 on either side of the moon pool. This arrangement permits the blowout pre venter stack assembly 18 to be moved into position over the moon pool while it remains anchored to the test stump.

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The blowout preventer stack assembly 18 is basically of conventional construction with one exception, which will be hereinafter described. Thus the blowout preventer stack assembly includes a frame consisting of at least three vertical guide pipes 24, 26, and 28 which are equally spaced from each other. The bottom end of the guide pipes are provided with conical skirts 30, for guiding the pipes onto mating alignment posts (not shown) on the base or template. Mounted within the framework, including the three guide posts, are the axi ally aligned blowout preventers indicated at 32 and 34. A conventional stab connector 36 is provided at the lower end of the stack assembly for connecting the stack onto the well casing. A riser stab assembly 38 provides a stab connection of the stack to a riser.

In order to provide positive guidance of the blowout preventer stack assembly 18 while lowering the stack down through the moon pool 14, there is provided a guidance assembly 40 mounted on the port side of the moon pool 14. The guidance assembly 40 includes two vertical tracks 42 and 44 in the form of rods or pipes which extend parallel to each other from a point sub stantially below the water line to a point slightly below the box girders 16. The lower ends of the guide rods 42 and 44 are tapered to a point. The guide rod 42 is supported by a framework which

can be assembled and disassembled to removably sup port the associated guide rod to the side of the moon pool. This framework assembly is shown schematically in FIG. 3. The supporting framework includes an upper pintle 46 and a lower pintle 48 connected to the rod 42 by an upper horizontal brace 50 and lower horizontal brace 52. The upper and lower pintles are held in spaced relationship by a vertical member 54. The upper end of the guide rod 42 is rigidly tied to the upper pintle 46 by a diagonal brace 56.

Lateral rigidity is provided by a rectangular frame as sembly including a pintle 58, horizontal member 60, diagonal member 62, and vertical brace 64. The outer end of the horizontal member 60 is in the form of a clevis which receives a bracket 66 extending from the brace 50. A removable pin 68 locks the bracket 66 in the clevis of the horizontal member 60. The upper end of the diagonal brace 62 is connected through a remov able collar 70 to the upper end of the guide rod 42. The pintles 46, 48, and 58 ?t into hinge brackets 72, 74, and 76, respectively, which are anchored to the sidewall of the moon pool 14. Thus the entire guide assembly 40 can be removed by lifting the pintles out of the hinge brackets 72, 74 and 76, and disassembling the assembly into two sections which can be readily stowed out of

the way. -

Details of the guide structure are shown in FIGS. 4, 5, and 6. The rod 42 is provided with a projecting or ra dial ?ange 78 which is welded to the guide rod 42 over substantially the full length thereof. The cross members and braces are made from pipe sections which are welded together in a conventional manner, the horizon tal members 50 and 52 being joined to the ?ange 78 by gusset plates 80 and 82. Similarly the upper end of the diagonal brace 56 is connected to the ?ange 78 by a gusset plate 84. The frame members 60, 62, and 64, as shown in FIG. 5, are made of pipe welded together. The free end of the horizontal member 60 is slotted to form a clevis. The slot ?ts over the ?ange 66 and a pin is in

serted through a hole 86.

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4 A short section of pipe 88 is welded to the upper end

of the diagonal brace 56, as shown in FIG. 6, and is cross-braced by a bracket 90. The outer end of the di agonal brace 62 is joined to the pipe section 88 by a collar 92 that is locked in place by pins 94 and 96 which are inserted through matching holes extending through the collar 92 and the ends of the pipe sections 62 and 88. The pins may have toggles on the ends for retaining the pins after they are inserted, or the pins may be conventional bolts. The guide rod 44 is removably supported from the

side of the moon pool by the same type-of supporting framework. Thus the guide rods 42 and 44 are held in vertical parallel relationship adjacent one side of the moon pool. As shown in FIG. 2, the blowout preventer stack 18

is positioned over the moon pool such that the guide post 26 on the stack assembly is opposite the guide rod 42. A false post 100 is provided on the stack assembly in circumferential position to be directly opposite the guide rod 44. The posts 26 and 100 of the stack assem bly 18 are linked to the guide rods 42 and 44 respec tively by conical guide assemblies 102 and 104, respec tively.

Referring to FIGS. 7 and 8, a conical guide assembly is shown in detail. The assembly 102 includes a cylin— drical sleeve 106 which is slotted along one side, as in dicated at 108. Secured to the top edge of the sleeve 106 is a conical section 110 which ?ares outwardly at the upper end. The conical section has a slot 112 along one side which is aligned with the slot 108. The aligned slots 108 and 112 permit the sleeve and conical section to slide along the guide rod 40 with the supporting ?ange 78 extending out through the slots. A pair of par allel ?at plates 1 13 and 114 project outwardly from the outside of the sleeve 106 and conical section 1 10 on ei ther side of the slots to provide guide surfaces for the supporting ?ange 78. The assembly is strengthened by annular reinforcing ?anges 116, 118, 120, and 122 which surround the outside of the sleeve and conical section and are welded thereto in a unitary structure. Radial plates 124 and 126 provide additional stiffness to the assembly. To connect the guide assembly 102 to the stack as

sembly 18, the guide post 26, which is .normally slotted along one side as indicated at 130 to permit a guide cable to be inserted through the center of the guide post 26, has a coupling framework permanently se cured to the outside of the post. This coupling assem bly, as shown in FIGS. 7 and 8, includes an annular ?ange 132 which surrounds the outside of the post 26 and has a radial slot 134 aligned with and matching the slot 130 in the guide post 26. Above the ?ange 132, an elongated vertically extending T~slot is formed by a pair of ?at guide plates 136 and 138 lying in a vertical plane tangential to the post 26 and being horizontally spaced from each other so as to provide a slot 139 be tween the inner edges of the plates. A radial ?ange 140 which is welded or otherwise rigidly attached to the sleeve 106 and conical section 110 forms a T~guide with a rectangular plate 142 secured to the outer pro jecting edge of the radial ?ange 140. The guide assembly 102 is detachably connected to

the guide post 26 by sliding the assembly down the rod 42 with the radial ?ange 140 slipping into the slot 139 between the plates I36 and 138 and with the guide plate 142 positioned between the guide post 26 and the

3,902,554 5

plates 136 and 138, as best seen in FIG. 8. The guide plate 142 is laterally restrained by angle guide members 144 and 146 which extend vertically upward from the ?ange 132 with the outer edges being welded or other wise attached to the plates 136 and 138, respectively. The inner edges of the angle guides 144 and 146 form a slot 147 extending parallel to the slot 130. A plurality of horizontal reinforcing plates 148 are axially spaced, the plates having an inner radius corresponding to the outside of the pipe 26 to which the plates are welded. The plates 148 are also welded to the vertical plates 136, 138 and the angle guides 144 and 146 to provide an integral rigid structure.

Initially the guide assemblies 102 and 104 are posi tioned adjacent the top of the guide rods 42 and 44. They are each held in this position by a locking pin 150 which is inserted through diametrically aligned holes 152 in the sleeve 106 when aligned with corresponding holes through the respective guide rods. This holds the guide assemblies 102 and 104 out of the way above the level of the coupling assembly on the guide post 26 and 100, as shown by the phantom position of the coupling assembly 102 in FIG. 1. After the sled 20 and stack as— sembly 18 are moved into position over the moon pool, the pin 150 is removed and the guide assemblies 102 and 104 are lowered into engagement with the top of the ?anges 132 and the transverse guide plates 142 po sitioned behind the plates 136 and 138. A locking pin 154 is inserted through aligned openings 156 extending through the plates 136, 142, and 144 to hold the guide assemblies in place. Once the guide assemblies 102 and 104 are coupled

respectively to the pipes 26 and 100, the stack assem— bly 18 can be lifted and the sled or cart 20 withdrawn. Depending upon whether there is suf?cient clearance or not, the lifting can be done in several ways. Assum ing suf?cient clearance, the rotary table can be moved back in position over the sub-base of the rig with the stack still on the sled 20. A riser is then lowered by the rig through the rotary table and stabbed into the riser connector 38. The riser is then used to lift the stack as sembly 18 off the sled 20 by means of the derrick rig, in conventional manner. After the sled 20 is removed, the riser and stack assembly are lowered as a unit by the rig down through the moon pool 14 to the template on the ocean floor. The coupling assemblies 102 and 104 provide positive guidance of the stack assembly along the length of the guide rods 42 and 44 until the stack assembly is substantially immersed in the water and the coupling assemblies slide off the lower end of the guide rods. When so immersed, swinging of the stack assembly is sufficiently damped by the water to prevent any substantial swinging of the stack from side to side as it is lowered on down through the bottom of the ship. When the blowout preventer‘ stack is retrieved after completion of the drilling operation, the conical sections 110 of the coupling assemblies 102 and 104 provide guidance for re-engaging the guide assemblies with the tapered lower ends of the guide rods 40 and 42.

If there is not suf?cient clearance for the stack as sembly to permit the rotary table to be moved into posi tion over the stack, a harness may be rigged from the box beams 16 and extending below the sled. The travel ing block of the rig is then used to lift the stack assem bly off the sled 20. The sled is then withdrawn and the stack assembly lowered down into the harness. The r0

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6 tary table can then be moved into position over the stack; the riser is then lowered through the rotary table and stabbed into the riser connector 38. In any case, it will be seen that the stack assembly is prevented from moving laterally at all times by the guide assembly.

Referring to FIGS. 9-14, an alternative guide struc ture, particularly adapted for a semisubmersible type drilling platform, is shown. The conventional semis ubmersible drilling platform includes a main deck 200 which is supported on a plurality of columns (not shown) which in turn-extend below the ocean surface to submerged hulls that give buoyant support. The main deck 200 is provided with a drilling opening 202. The main deck may be held high above the level of the water to permit high waves to pass beneath the struc ture. A vertical guidance assembly for guiding the stack assembly while it is being lowered through the drilling opening and into the water includes a girder structure extending down from the underside of the main deck 200 to a point slightly above the normal water level. This structure includes a pair of vertical parallel I beams 204 and 206. The lower ends of the I-beams are joined to diagonal braces 208 and 210 by gussett plates 212. The upper ends of the diagonal braces 208 and 210 are anchored to the underside of the main deck 200 by suitable anchoring plates 214. The upper ends of the I-beams 204 and 206 extend past one edge of the opening 202 and terminates well above the level of the main deck 200 adjacent one side of the drilling opening 202. Diagonal braces 216 and 217 extend from the upper ends down to the deck 200. The I-beams 204 and 206 are made more rigid by means of horizontal and diagonal cross bracing between the I—beams 204 and 206 and the diagonal members 208 and 210 to form rigid trusses. '

The upper ends of the I-beams 204 and 206 are con nected by a horizontal top beam 218 which projects horizontally beyond the I'beams at either end. Lateral rigidity is provided for the I-beams 204 and 206 by di agonal braces 220 and 222 which are joined at their lower ends to the deck 200 and at their upper ends to the I-beams 204 and 206. The vertical beams 204 and 206 support vertical

tracks or guides 224 and 226 which are in the form of semi-circular channels which extend from the level of the deck 200 down to the lower end of the supporting I-beams. Stiffening ?anges 228 and 230 run the length of the guides on the outside of the channels. Integral supporting brackets 231 are spaced along the length of the tracks for securing the tracks to the supporting framework. Each bracket includes a horizontal plate 232 and a backing plate 234. The backing plates are bolted or otherwise secured to respective horizontal cross-brace members 236. The lower ends of the tracks 224 and 226 terminate in flared or bell-mouth sections 238 and 239 for guiding the blowout preventer stack frame on and off the lower end of the tracks. As shown in FIG. 9., the blowout preventer stack in

cludes four guide posts 240, 242, 244, and 246. A guide framework is added to the blowout stack assembly which includes a pair of spaced parallel guide rods 248 and 250. The guide rods 248 and 250 are rigidly sup ported from the guide posts 240 and 242 by a suitable tubular framework, indicated generally at 252, which includes horizontal tubes 254 extending between and secured to the guide rods 248 and 250 and connector tubes 256 and 258 which extend between the guide

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post 248 and 250 and the horizontal tubes 254. Suit able cross bracing tubes, such as 260 and 262, provide rigidity to the guide framework 252. As in the embodiment described above in connection

with FIGS. 1-8, the blowout preventer stack assembly is normally stored on a test stump in the form of a sled or cart which is suf?eiently large to span the drilling opening 202. Thus the cart can be used to move the blowout preventer stack assembly into position over the drilling hole with the rods 250 and 248 aligned with the lower guide tracks 224 and 226. To lock the blow out preventer stack assembly in proper position for lowering the assembly through the drilling opening 202, a pair of upper guide track guide sections 264 and 268 are arranged to be moved apart out of alignment with the lower guides 224 and 226. To this end, the upper end of the guide section 264 includes a bracket assembly 270 which is pivotally connected to the cross member 218 by a hinge bolt 272. Similarly the upper end of the guide section 268 has a bracket 274 which is pivotally supported from the cross member 218 by a hinge bolt 276. As best seen in FIG. 10, with the bolt 272 as the pivot axis, the upper guide section 264 can be swung to one side where it can be held by a locking pin 278 which extends through a bracket 280 secured to the lower end of the guide section 264 and a hole in plate 282 secured to the diagonal brace 222. The upper end of the guide section 264 has the outer half of the channel removed along a diagonal line 284 so that when the guide section 264 is pivoted off to one side, there is clearance for the guide rod 248 to move into position against the back of the channel. The upper end of the upper guide 268 is similarly relieved along a di agonal 286. Once the guide rods 248 and 250 are moved into po

sition so as to be aligned with the lower guides 248 and 250, the upper guides 264 and 268 are swung into a vertical position in which the channels fit around the guide rods 248 and 250. In this position, the locking pin 278 is inserted through an aligned hole in a cross mem ber 288. Sirriilarly a pin 290 is used to lock the lower end of the guide section 268 in its operative vertical po sition to the cross member 288 or to the open position to a plate 292 on the diagonal brace 220. What is claimed is: 1. Apparatus for guiding a blowout preventer assem—

bly and the like along a predetermined path during movement of the assembly to and from an off-shore drilling installation out of and into water over a well— head, the apparatus comprising: guide means rigidly se curable to the drilling installation de?ning a pair of spaced vertical tracks disposed parallel to and to one side of the predetermined path so as not to limit the horizontal dimension of a blowout preventer assembly being handled, the tracks having lower ends disposed so that when a blowout preventer assembly engages or disengages the tracks the assembly is substantially im mersed in water, the tracks having upper ends above the location in the installation at which the blowout preventer assembly is stored, guide elements engage able with the tracks and secured to the blowout pre venter assembly for movement therewith along the ‘path out of and into engagement with the lower ends of the tracks, the guide elements being cooperatively con ?gured in association with the tracks for locking the guide elements to the tracks to restrict motion of the guide elements to movement lengthwise of the tracks

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8 when engaged therewith, and means for coupling and decoupling the blowout preventer assembly via the guide elements to the tracks at a location between the upper and lower ends of the tracks substantially adja» cent the storage location of the assembly.

2. In an off-shore ?oating drilling vessel subject to heave, roll, and pitch, apparatus for guiding equipment while lowering the equipment from the top of the vessel through an opening into the water comprising: track means including a pair of parallel tracks vertically mounted to the vessel and extending from above the opening down through the opening, the tracks being rod-shaped with a supporting ?ange extending length wise of the track for supporting the track from the ves sel, guide means engaging the tracks and movable therealong, and means coupling the guide means to said equipment, the guide means moving with the equipment as it is lowered through the opening to guide the equipment along the tracks into the water, the guide means disengaging from the tracks as the equip ment enters the water, the guide means including sleeves having a slot, the sleeves slidably engaging the respective tracks with the ?anges extending through the slots.

3. Apparatus of claim 2 wherein the coupling means includes means for detachably connecting the sleeves of the guide means to the equipment.

4. Apparatus of claim 3 wherein the means for de tachably coupling the respective sleeves to the equip ment includes means forming a T -slot extending verti cally of the equipment, and T-shaped members project ing from each sleeve adapted to slide into the T-shaped slot by sliding the associated sleeve along the track, and means for locking the T-shaped member in the mating slot.

5. In an off-shore ?oating drilling vessel subject to heave, roll, and pitch, apparatus for guiding the equip ment while lowering the equipment from the top of the vessel through an opening into the water comprising: track means including a pair of parallel tracks vertically mounted to the vessel and extending from above the opening down through the opening, guide means en gaging the traeks and movable therealong, means cou pling the guide means to said equipment, the guide means moving with the equipment as it is lowered through the opening to guide the equipment along the tracks into the water, the tracks being channelshaped, the guide means including means slidably engaging the channels, the channels opening in opposite directions relative to each other to retain the guide means in the

channels. 6. Apparatus of claim 5 wherein a portion of at least

one of the track channels adjacent the upper end is movable in the direction toward and away from the open side of the channel to permit the guide means to be positioned within the channels.

7. Apparatus for guiding a blowout preventer assem bly and the like along a predetermined path during movement of the assembly to and from an off-shore drilling installation out of and into water over a well head, the apparatus comprising: guide means rigidly se curable to the drilling installation defining a pair of spaced tracks disposed parallel to the predetermined path, the tracks having lower ends disposed proximate the water surface below the location in the installation at which a blowout preventer assembly is stored, the tracks having upper ends above said assembly storage

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location, guide elements securable to a blowout pre venter assembly as a part of the structure thereof for movement with the assembly to and from the wellhead and engageable with the tracks, the guide elements being cooperatively con?gured in association with the tracks for substantially only sliding motion along the tracks when engaged therewith, and means for cou pling and decoupling a blowout preventer assembly via the guide elements to the tracks at a location on the tracks between the ends thereof.

8. A method of transferring a blowout preventer stack, having secured thereto an outer frame with verti~ cal guide members, from the deck of a drilling vessel into the water by a drilling rig positioned over a drilling opening in the deck, comprising the steps of: mounting the stack on a movable frame for storage on the deck, moving the frame over the opening, coupling the stack frame guide members to vertical guides located only on one side of the opening while supporting the stack on the movable frame, lifting the stack along the vertical guides off the movable frame, removing the movable frame, and lowering the stack into the water along the vertical guides.

9. A method of lowering a blowout preventer stack having secured thereto an outer frame with vertical guide members from the deck of a drilling vessel through a drilling opening in the deck below a drilling rig, comprising the steps of: mounting the stack on a

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10 test frame supported on the deck, moving the test frame over the opening, securing the vertical guide members to vertical tracks extending above and below the deck without vertical movement of the stack from the frame, lifting the stack along the tracks off the test frame, removing the test frame, and lowering the stack and the guide members therewith along the tracks into the water.

10. In an off-shore ?oating drilling vessel subject to heave, roll, and pitch, apparatus for guiding the equip ment while lowering the equipment from the top of the vessel through an opening into the water comprising: track means including a pair of parallel tracks vertically mounted to the vessel and extending from above the opening down through the opening, guide means en— gaging the tracks and movable therealong, means cou pling the guide means to said equipment, the guide means moving with the equipment as it is lowered through the opening to guide the equipment along the tracks into the water, the guide means disengaging from the tracks as the equipment enters the water, the track means including a framework attached to each track, and means detachably connecting the frame work to the vessel to permit the tracks to be removed from the structure of the vessel around the opening