ocean tow guidelines[1]

GENERAL OCEAN

TOW RECOMMENDATIONS

FOR JACKUP DRILLING UNITS International Association of Drilling Contractors

(I.A.D.C.)

February 13, 1991

Manning

1.Manning should comply with U.S. Coast Guard regulations or other national regulatory rules. The number of crew will be dependent on the length of the voyage and be limited to essential personnel only and should not exceed 50 % of lifeboat capacity.

Ocean Tow Loading Plan

2. A Loading Plan should be formulated and, if required, submitted to the Underwriter’s Marine

Survey company utilized by the Contractor for the tow in time for proper review. (See

Addendum A enclosed for a sample loading plan)

3.Cargo is defined as any material, temporary structure, shipping container, consumable item,

machinery, tubular, equipment and items not included in the drill barge lightship weight.

4.Stowage of on the main weather deck of a Jackup drilling unit while on an ocean tow is not

desirable and should be avoided with the exceptions noted below.

5.Exceptions to this policy my be permitted if:

a. A permanent structure has been erected for the stowing and securing of an item such as a

pipe rack for drill pipe and drill collars, or a mandrel and locking beams for a BOP. The

permanent structures should be adequate for their intended purpose, reviewed, and

approved by a classification society in accordance with the appropriate rules.

b.Cargo is elevated or located above the main deck by mans of a suitable support structure.

c.Temporary structures are permitted when designed by a registered professional engineer

and approved by the underwriter’s marine surveyor.

Towage

6.One set of up-to-date navigation charts and pilot books for the tow course and alternate courses

should be available for the voyage aboard the rig including detailed charts of ports of refuge. 7.Tow routing should be determined in advance including ports of refuge and the required entry

data.

8. A weather service should be selected with a beck ground in ocean tow forecasting. Weather

updates should be sent every 12 hours with at least 72 hour advance forecasts. Direct

communication with a marine weather forecaster is recommended.

9.The Towing vessel(s), and towing gear, should be designed and equipped for towing in ocean

service with full crew aboard. Towing gear should be inspected and approved by the attending

marine and the O.I.M. prior to departure.

10.The bollard pull of the towing vessel(s) should be of sufficient size for the intended tow.

https://www.wendangku.net/doc/bb7772325.html,munication means between the rig and the towing vessel(s) is of utmost importance. Backup

communications should be provided. The vessel should provide a qualified riding crew member to assist the rig crew during tow. Language should not be a barrier.

12.Critical motion curves should be provided to the rig crew and th e towing vessel(s) prior to

departure. (see addendum B) Manufacture recommendations for proper leg length and shimming should be adhered to for the tow.

13.An emergency towing line should be strapped along the side of the hull just below top deck level

in a manner permitting quick release. me tow line should be of a size suitable for the tow

intended accounting for the bollard pull of the tow vessel(s), including shock loads.

14. A polypropylene shock line, the size and length suitable for the bollard pull of the tow vessel(s)

being used, should be attached to the emergency tow line with suitable connectors.

15. A main tow line bridle recovery line(s) should be fitted and run from the and of the bridle or tow

plate to a winch on the barge to allow retrieval in the main tow wire(s) part.

Stability

16.stability calculations addressing the tow conditions should be performed to insure positive

stability in compliance with the rig operating manual. These calculations should be submitted to and approved by the underwriter's Marine Survey company being utilized in time for proper

review. (see Addendum A)

Draft and Trim

17.Within the limits of the loadline certificate, the man draft for the tow should be determined from

the stability calculations in item 16 above.

18.Weight should be distributed to produce a level condition transversely with a slight trim by the

stern. Trim is to be obtained by locating material or equipment carried with necessary liquid

trimming ballast kept to a minimum.

19.Liquid variable load should be kept to a minimum. Hull tanks that contain liquids should be

pressed and maintained full during the voyage.

20.All tanks, including active mud tanks, not required on the voyage, should be empty at the time of

departure.

Watertight Integrity

21.The operating manual for the rig should clearly show the location of watertight closures and

should be complied with during the tow.

22.Deck openings such as sounding tubes should be protected from damage

23.Consideration should be given to the modification all weather deck preload hatch covers, vent

fan covers, cargo hatch cover, etc. with clamp bars or welded strapping to prevent opening from sea action.

24.Rig service take on lines Such as out, barite, fuel, potable water, or drill water located on the

outer lull areas should be capped and protected from sea damage by sea action.

25.All weather/watertight closures, ventilation ducts, etc. with the exception of intakes necessary for

the operation of the vessel, should be seed from sea action.

Pumping Arrangements

26.The vessel's bilge/ballast service pumps should be tested and determined to be in good working

order prior to departure. Pumps are to be maintained in a state of readiness throughout the tow. Compartment Sounding

27.All hull compartments and void spaces should be fitted with sounding tubes. All sounding tubes

should be clearly identified and fitted with caps that are capable of being tightly secured.

28.Soundings should be taken at least every 12 hours of all void and preload tanks. Hull

compartments should be inspected or sounded also and the results should be logged for the

duration of the

29. A diagram of the sounding tube locations should be posted in the machinery deck spaces and in

the control room.

30. A means of determining the changes in liquid levels in the perimeter hull tanks must be available

for use from a protected location.

31.The manufacturer's data should be furnished to indicate that the derrick can withstand the roll

motions anticipated for the tow. This data should be in the rig operating manual.

32.All Derrick traveling equipment should be seared for the tow.

33.Bow anchors should be removed from below water racks and strapped to the deck or stored if

there is the possibility of becoming entangled in the tow gear.

34.Secure or remove anchor buoys from their racks to prevent dislodging by sea action.

Cranes

35.Crane should be lowered into steel support structures and secured against vertical or lateral

movement.

36.Cranes should be secured against revolving per manufactures recommendations.

Navigation Lights, Signals and Safety Equipment

37.Side Lights and stern light should be checked to make sure they are in good working order.

38.Life vests, throw over life rings and other means of rescue should be checked and readied for

deployment, if need.

39.Signaling devices should be stored in the control room, inspected and determined that they are

within inspection dates for use, if needed.

Potable Water and Fuel Oil

40.Sufficient potable water and fuel for the length of the tow, plus 25% safety factor, should be

carried.

41. A potable pump should be available to obtain water from the potable water tanks in the event of

pump failure.

42.Because sediment in the fuel tanks can be stirred up during tow, a centrifuge should be installed

prior to departure to remove contaminants from the fuel pumped to the engine day tanks. Extra

engine fuel filters should be in supply.

Damage Control

43.The following emergency and/or damage control eq uipment and material is recommended to

carried aboard for the tow, or it's equivalent.

400 lbs. cement

400 lbs. sad

20 lbs. concrete mix accelerator

40 ft. of 1" x 12" timber

24 lbs. of oakum or similar caulking compound

24 wooden wedges

24 wooden plugs of various sizes

Welding and cutting apparatus

50 ft. of 4" x 4" angle iron

100 sq. ft. of 1/2" steel plate.

100 sq. ft. of 1" steel plate

500 ft. 1" polypropylene rope

500 ft. 1" wire rope

20 Ton Portapower hydraulic jack

100 ft. 2" x 4" x 10’ timber

Two portable diaphragm air pumps

44.Spare shackle, heaving lines, turnbuckles, etc. should be aboard for the tow.

45.Fog horn, ship whistle or bell, search light, etc. should be in operating condition.

46.Secure all equipment in the accommodations area for heavy seas.

47.Strip water from the preload tanks, unused drill water tanks and void tanks prior to and during

the tow.

48.Lifeboat machinery and equipment should be checked for compliance with existing regulations

and be in proper operating condition. Lifeboat fuel tanks should be checked for contaminants and feel cleaned or replaced as necessary Spare fuel filters should be stowed aboard the lifeboat for

use, if required.

49.The emergency power source should be available for use at all times and teed at periodic

intervals

Riding Crew Instructions

50.Sea watches should be maintained at all times during the tow. The following information should

be entered into the log:

a.Weather data including; wind force, wave/swell height/Period.

b.Motion characteristics of the vessel are of the utmost importance. The Drill Barge Master

(licensed or unlicensed) must observe degrees of pitch and roll and their corresponding

periods and request the tug to change course and/or speed to prevent the Drill Barge

motions from exceeding the values given in the Operations Manual critical motion

curves.

c.All important communication with the towing vessel(s) including speed, course, change

in tow wire length, etc. should be recorded.

d.me Position should be obtained from the towing vessel(s) every 6 hours and recorded in

the rig log.

51.Each hull tank should be sounded and logged every 12 hours.

52.All watertight doors between compartment and from the compartments to outside exits should be

kept closed at all times except when personnel pass.

53.Tow gear should be inspected every 6 hours and the results logged.

54.At least two (2) members of the crew should be awake at all times.

55.Radio contact mist be maintained on a 24 hour basis with the tow vessel(s).

56.Emergency drills should be held prior to departure and once a week during the tow. Results

should be logged.

57.All navigation lights should be checked every 6 hours and the results logged.

58.Daily reports are should be forwarded to the Contractor’s headquarters at least daily.

OCEAN TOW LOADING PLAN

ADDENDUM A

FEBRUARY 13, 1991

ADDENDUM A

TO:General Marine Surveyor Company

FROM:United Marine Drilling Contractors

SUBJ:Ocean Tow Stowage Plan

Please review the enclosed Ocean Tow Loading Plan for our 116 class hull. The loading plan is comprised of the following:

1. A completed loading calculation for the start of the tow based on the latest information from our

rig survey. The stability calculations are based on two leg down positions (12.17 ft. for 70 knots and 45.90 ft. for severe storm).

2.All loose gear will be stowed below deck in stowage areas 11 through 13 and secured to prevent

shifting during the tow. (see enclosed drawings)

3.The drilling tubulars will be secured with turnbuckles and chain and containment barriers will be

fabricated at the ends of the racks, subject to your final approval. Four areas are anticipated at

this time. (see enclosed drawings)

4.Two miscellaneous cargo areas will be constructed on top of the quarters in containment areas in

order to remove these items from possible sea action. (see enclosed drawings)

5.The Substructure/drill floor assembly will be in the full forward position for the tow and secured

to the hull with the clamping arrangement provided by the manufacturer.

6.The emergency tow gear will be strapped along the port side of the hull and provisions made for

the deployment in severe weather if the need should arise.

7.The deepwell tower will be secured to the hull with clamping arrangements designed by the

manufacturer. Three 3/4 inch guy wires will be connected to the tower in three different

directions securing the tower from the rig motions anticipated.

Please review the Loading Plan provided at this time. As you kn ow, final loading will depend on your survey prior to the departure of the rig.

ADDENDUM B FEBRUARY 13, 1991