GB1597151A - Diving bell launch tube - Google Patents
Diving bell launch tube Download PDFInfo
- Publication number
- GB1597151A GB1597151A GB17314/77A GB1731477A GB1597151A GB 1597151 A GB1597151 A GB 1597151A GB 17314/77 A GB17314/77 A GB 17314/77A GB 1731477 A GB1731477 A GB 1731477A GB 1597151 A GB1597151 A GB 1597151A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tube
- diving
- surge chamber
- bell
- sea
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
- B63C11/00—Equipment for dwelling or working underwater; Means for searching for underwater objects
- B63C11/34—Diving chambers with mechanical link, e.g. cable, to a base
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
- B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
- B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
- B63B1/107—Semi-submersibles; Small waterline area multiple hull vessels and the like, e.g. SWATH
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B3/00—Hulls characterised by their structure or component parts
- B63B3/14—Hull parts
- B63B2003/147—Moon-pools, e.g. for offshore drilling vessels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B27/00—Arrangement of ship-based loading or unloading equipment for cargo or passengers
- B63B27/16—Arrangement of ship-based loading or unloading equipment for cargo or passengers of lifts or hoists
- B63B2027/165—Deployment or recovery of underwater vehicles using lifts or hoists
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
- B63B39/06—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water
- B63B2039/067—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water effecting motion dampening by means of fixed or movable resistance bodies, e.g. by bilge keels
Landscapes
- Ocean & Marine Engineering (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Combustion & Propulsion (AREA)
- Chemical & Material Sciences (AREA)
- Fluid Mechanics (AREA)
- Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
- Earth Drilling (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
- Underground Structures, Protecting, Testing And Restoring Foundations (AREA)
- Steroid Compounds (AREA)
- Special Spraying Apparatus (AREA)
- Instructional Devices (AREA)
Description
(54) DIVING BELL LAUNCH TUBE
(71) We, THE BRITISH PET
ROLEUM COMPANY LIMITED, of Britannic House. Moor Lane, London EC2Y 9BU, a British Company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
The present invention relates to diving bell launch tubes and more particularly to means for facilitating the lowering and raising of the diving bell into the sea during disadvantageous sea conditions.
The use of diving bells for sub-sea operations, e.g. maintenance of pipelines, production platforms and rigs, has become of increasing importance. However, the time available for the operation is often limited because of unfavourable sea conditions. The heaving of the sea poses problems of entry of the bell into the water and can cause physical discomfort to the diving personnel thus impairing work capacity and basic safety conditions and causes serious risk of bell wire breakage.
In diving operations one method of launching a diving bell is by raising and lowering the bell through the air/sea interface in a well or shaft within a ship or vessel. In unfavourable sea conditions the pulsing of the water in the tube can buffet the bell during passage down the shaft and can prejudice the safety of the bell personnel.
The present invention relates to a well or shaft which allows improved transition of the bell across this air/sea interface and which has the advantage of being a substantially passive system in that there are no or few moving parts.
Thus, according to the present invention there is provided a launch tube for launching underwater craft through an air/liquid interface e.g. diving bells, the tube comprising a substantially vertical passageway having a surrounding surge chamber adjacent to the air/liquid interface, the surge chamber communicating with the passageway through a perforated section of the passageway, the chamber and perforations being of a size and distribution in relation to the passageway such that there is damping of liquid oscillation in the tube. The launch tube may be separate or be associated with a conventional ship, semi-submersible craft or the like.
Diving bells are preferably of the conventional type having a thick walled steel sphere enclosing the diving personnel and equipment. Preferably the sphere is supported by a tripod or leg arrangement and in operation is passed into the launching tube by a cable and winch arrangement. Also it is envisaged that manned or unmanned submersibles e.g. small submarines, may be launched via these tubes.
For use with a semi-submersible rig, the passageway of the launching tube may pass from the upper deck of the rig through the surge chamber or pontoon of the rig and thence opens into the sea proper at the keel.
It is desirable that the still sea water level lies within or just below the surge chamber and preferably is located at a point about halfway up the surge chamber.
The perforated section of the launching tube connects the interior of the passageway to the surge chamber and has preferably circular or elliptical apertures. Preferably the surge chamber has one or more diaphragm plates, either horizontal or vertical, depending on convenience, which are also perforated, preferably with circular or elliptical apertures so as to allow intercommunication between the resulting sections formed by the plates. The vertical passageway is preferably of a circular cross-section.
The surge chamber may be of a similar cross-section to that of the vertical passageway or launch tube or it may be of different cross-section (e.g. square).
Around the exit of the flow tube, a supply of high pressure gas may be used to aerate the water inside the tube. A perforated high pressure air tube is preferably used. It is believed that the aeration acts by reducing the effective density of the water in the tube thereby reducing the hydrodynamic forces on the bell.
The areas of the apertures of the perforated section of the vertical passageway and the volume of the surrounding surge chamber are preferably "tuned" so as to achieve maximum damping of the osciliating column of sea water when unsteady sea conditions are present. This "tuning" may be achieved by varying the size, shape and spacing of the apertures and the shape and volume of the surge chamber. Thus it is envisaged that asymmetric apertures and surge chambers may be used.
The tuning of the surge chamber occurs in the design stage and each system is tailored to suit an individual ship or the like by observing behaviour in model test conditions. Thus, depending on the wave conditions likely to be experienced by the ship, a model test of a surge chamber is carried out to obtain optimum wave damping in the bell under the specified wave height and frequency. The surge chamber design resulting from the model tests is then scaled up and built into the operational vessel.
In general, significant wave heights and periodic times of up to 7-9 metres and 20 secs respectively may be expected to be encountered and the volume of the surge chamber is preferably from 1 to 5 times the volume of the section of passageway that it surrounds. The apertures preferably have
an area of from 50 to 150% of the surface
area of the section of the passageway surrounded by the surge chamber and most
preferably are uniformly distributed.
The invention also includes a method of launching underwater craft into a liquid whereby (i) the craft is lowered into a launch tube as hereinbefore defined, (ii) the craft is passed through the liquid/air interface, and (iii) is passed out of the tube into the surrounding liquid.
The invention will now be described by way of example only with reference to
Figures 1 to 4 of the accompanying drawings.
Figure 1 shows a diagrammatic representation of a semi-submersible rig capable of accommodating a diving tube according to the invention.
Figure 2 shows a vertical section through the diving tube centre line and Figure 3 shows a more detailed section of the surge chamber of Figure 2. Figure 4 shows recorded spectra of wave height and time for waves amidships of the rig and for waves in a launch tube fitted with a surge chamber.
A semi-submersible rig 1 has in Figure 1) has a pair of pontoons 2, 3 lying beneath the water surface and a main deck 4 and lower deck 5 above the water surface. Each pontoon 2, 3 is joined by three vertical supports 6 to the deck 4.
One of the supports 6 is adapted to have a vertical diving tube 7 passing between the decks and allowing access to the sea below via the pontoon 3.
At the upper end of the diving tube 7, an area 8 is provided for diving equipment and gas bottle stowage which are accessible from the decks 4, 5.
The diving tube 7 has an internal diameter of about 3 m and extends downwardly from the lower deck for a distance of about 20 m.
At the sea level the diving tube 7 has a perforated section 9 about six metres long which communicates with a surrounding surge chamber 10 which takes the form of a rectangle (of side 6 x 4.6 x 5 m). The diving tube 7 then extends downwards through the pontoon 3 via a section 11 into the sea beneath the semi-submersible rig 1.
The perforated section 9 of the walls of the diving tube 7 comprise seven rows of circular cut outs, each row having 12 x 300 mm diameter holes. The perforated section 9 is supported inside the surge chamber 10 by three horizontal diaphragm plates 12, each plate 12 being pierced by sixteen elliptical cut outs 13 of major and minor diameters 700 x 350 mm which allow water flow to occur within the surge chamber 10.
During use of the diving tube, a diving bell is lowered into the tube 7 by a winch on the lower deck of the semi-submersible rig.
The bell passes through the air space until it reaches the air/sea interface within the perforated section 9 of the tube 7. In steady sea conditions the bell can cross the air/sea interface and pass along the tube 7 until it reaches the sea proper. In non-steady sea conditions the oscillation of the sea level within the tube 7 is considerably damped by the action of the surge chamber 10. This reduction in sea level oscillation within the tube facilitates the passage of the diving bell and personnel across the air/sea interface, ie. reduces the heaving and pitching of the bell and hence increases the safety conditions under which the bell operates.
The dimensions of the surge chamber were determined from a series of model tests at a scale of 1 : 20. The diving tube system was built of transparent PVC plastic together with the starboard centre column and 28 m of the starboard hull around the column. The perforations around the surge damping chamber were made to the correct opening areas.
A calibrated hoisting winch with variable speed was placed over the diving tube. The winch was relieved of the constant weight of the bell by means of a contra weight.
Around the orifice at the bottom exit of the diving tube an 8 mm diameter (model scale) aeration tube was fitted with 18 1 mm holes equally spaced on the inner side pointing 30 downward. Compressed air was led to the aeration tube through a flowmeter. The air flow was calibrated to a constant value of 1.58 x 10-4m3/s corresponding to a full scale value of:
Q = 1.58 x 10-4 x 205/2 = 0.28 m3/ = 600 ft3/min
The whole diving tube system model was fitted to an SL vertical planar motion mechanism in order to simulate heave motions of different amplitudes and frequencies.
The diving bells were manufacturers of wood and copper tube in accordance with drawings. A pyramid shape frame was mounted on top of the bell in order to ease the re-entry into the diving tube. The diving bells were ballasted with lead weights to simulate the weight of the full scale bell to be used. Due to small volume differences between models and prototypes, it was not possible to match weights in air and water
exactly.
The waves were produced by a digitally controlled pneumatic wave maker.
Figure 4 shows pen recordings of wave height against time of typical model tests of the surge chamber when subjected to waves (a) at 84% of full operating draught with irregular waves having Tmean = 10.33 secs and H1,3 = 6.71 metres where Tmean is the mean time period of the waves and H113 is the significant wave height, (b) at 100inc full operating draught with regular waves having
Tmean = 12.5 secs and H1,3 = 3.6 metres and (c) at 100% full operating draught with irregular waves having Tmean = 10.27 secs and H113 = 5.89 metres. The ordinates are in metres and the abscissa is the time of full
scale and not model scale.The runs (a), (b) and (c) illustrate the marked reduction in wave height which occurs in the diving chamber within the vessel compared to the wave height outside the amidships of the vessel.
WHAT WE CLAIM IS:
1. A launch tube for launching underwater craft through an air/liquid interface comprising a substantially vertical passageway having a surrounding surge chamber adjacent to the air/liquid interface the surge chamber communicating with the passageway through a perforated section of the passageway. the chamber and perforations being of a size and distribution in relation to the passageway such that there is damping of liquid oscillation in the tube.
2. A launch tube according to claim 1 in which the perforated section of the vertical passageway has circular or elliptical apertures.
3. A launch tube according to claim 1 or 2 in which the surge chamber has one or more perforated diaphragm plates.
4. A launch tube according to claim 3 in which the diaphragm plates are horizontal.
5. A launch tube according to claim 3 or 4 in which the perforated diaphragm plates have elliptical or circular apertures.
6. A launch tube according to any of the preceding claims in which the surge chamber and the vertical passageway have a circular cross-section.
7. A launch tube according to any of the preceding claims in which the volume of the surge chamber is from 1 to 5 times the volume of the vertical passageway surrounding it.
8. A launch tube according to any of the preceding claims in which the apertures have an area of from 50 to 1506 of the surface area of the section of the passageway surrounded by the surge chamber.
9. A launch tube according to any of the preceding claims including a diving bell.
10. A launch tube as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.
11. Water going craft having a launch tube according to any of the preceding
Claims (1)
- claims.12. A method of launch in underwater craft into a liquid whereby (i) the craft is lowered into a launch tube according to any of claims 1 to 11, (ii) the craft is passed through the liquid/air interface in the surge chamber, and (iii) is passed out of the tube into the surrounding liquid.
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB17314/77A GB1597151A (en) | 1977-04-26 | 1977-04-26 | Diving bell launch tube |
DE2816995A DE2816995C2 (en) | 1977-04-26 | 1978-04-19 | Manhole pipe for guiding a diving bell or the like. |
FR7811758A FR2388715A1 (en) | 1977-04-26 | 1978-04-20 | LAUNCHING TUBE FOR PLUNGER BELLS AND PROCESS FOR LAUNCHING A SUBMERSIBLE INTO A LIQUID USING LEDIT TUBE |
JP4673178A JPS53133898A (en) | 1977-04-26 | 1978-04-21 | Launching tube |
DK177578A DK177578A (en) | 1977-04-26 | 1978-04-24 | SOESAETNINGSROER |
SE7804708A SE421773B (en) | 1977-04-26 | 1978-04-25 | SHAKT FOR LAUNCHING AND RECORDING OF AN UNDERWATER COAST |
NO781444A NO147826C (en) | 1977-04-26 | 1978-04-25 | SJOESETTINGSROER. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB17314/77A GB1597151A (en) | 1977-04-26 | 1977-04-26 | Diving bell launch tube |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1597151A true GB1597151A (en) | 1981-09-03 |
Family
ID=10093009
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB17314/77A Expired GB1597151A (en) | 1977-04-26 | 1977-04-26 | Diving bell launch tube |
Country Status (7)
Country | Link |
---|---|
JP (1) | JPS53133898A (en) |
DE (1) | DE2816995C2 (en) |
DK (1) | DK177578A (en) |
FR (1) | FR2388715A1 (en) |
GB (1) | GB1597151A (en) |
NO (1) | NO147826C (en) |
SE (1) | SE421773B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU704413B2 (en) * | 1995-12-06 | 1999-04-22 | Fred Olsen | Wave dampener for floating structures |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2058180B (en) * | 1979-09-15 | 1983-06-22 | British Petroleum Co | Diving structure and method of deploying |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2488542A (en) * | 1945-06-28 | 1949-11-22 | Amer L Houghtaling | Artificial island |
US3605417A (en) * | 1968-06-04 | 1971-09-20 | Marcelo Edmundo Wolf | Device for protecting divers from strong underwater currents |
US3641961A (en) * | 1970-05-25 | 1972-02-15 | Pan American Petroleum Corp | System for lowering a subsea device from a vessel |
NO136084C (en) * | 1974-02-15 | 1977-07-20 | Akers Mek Verksted As | DEVICE FOR VESSELS FOR CARRYING DIVING WORK USING A DIVING CLOCK. |
NO142702L (en) * | 1974-05-16 |
-
1977
- 1977-04-26 GB GB17314/77A patent/GB1597151A/en not_active Expired
-
1978
- 1978-04-19 DE DE2816995A patent/DE2816995C2/en not_active Expired
- 1978-04-20 FR FR7811758A patent/FR2388715A1/en active Granted
- 1978-04-21 JP JP4673178A patent/JPS53133898A/en active Pending
- 1978-04-24 DK DK177578A patent/DK177578A/en not_active Application Discontinuation
- 1978-04-25 NO NO781444A patent/NO147826C/en unknown
- 1978-04-25 SE SE7804708A patent/SE421773B/en not_active IP Right Cessation
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU704413B2 (en) * | 1995-12-06 | 1999-04-22 | Fred Olsen | Wave dampener for floating structures |
Also Published As
Publication number | Publication date |
---|---|
FR2388715B1 (en) | 1985-01-25 |
NO781444L (en) | 1978-10-27 |
JPS53133898A (en) | 1978-11-22 |
NO147826B (en) | 1983-03-14 |
DK177578A (en) | 1978-10-27 |
NO147826C (en) | 1983-06-22 |
DE2816995C2 (en) | 1986-07-10 |
SE7804708L (en) | 1978-10-27 |
DE2816995A1 (en) | 1978-11-02 |
FR2388715A1 (en) | 1978-11-24 |
SE421773B (en) | 1982-02-01 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |