Planning notes for the moorings

(This is an excerpt from notes describing a planning meeting held during 27-28 June 2002 and responses to issues raised during that meeting.)

Mooring details

• Instruments include 29 Anderaa current meters, 20 MicroCats, one SeaCat pressure gauge and one upward looking SonTek ADCP. There will be 11 moorings, but only 9 will be recovered and redeployed on AnSlope I. (NOTE: It is still undetermined whether only 9 or all 11 moorings will be recovered and redeployed. The grantees have provided sufficient anchors to accommodate all possibilities.) RPSC will provide 3 MicroCats and associated hardware for an additional mooring. All have mounting brackets permitting placement on 5/8" rods or line. AnSlope PIs are expected to provide anchors, line, and floats necessary for this additional mooring.
• RPSC can provide eight 17" glass ball floats as backup for grantee-provided gear.
• Grantees have already procured mooring anchors, so RPSC will not provide these.
• 3/8" Samson braid rope will be used on moorings. Breaking strength is approximately 7200 lbs.
• Grantees will provide HPU (440 V, 3 phase), traction winch, spooler, reel stand, deck cleats, turning lines, sheave, quick releases, grappling hooks, instruments. RPSC will provide large sheave (capable of 1500 lb. load), chain and binders for anchors, tugger winches, electric/hydraulic power, extra hydraulic lines, fittings, hoses, connectors, and regulators
• Instruments will have battery power for 30 months at initial deployment so that data is not lost if recovery in not possible at the end of AnSlope I or AnSlope III.
• All moorings are single-release.
• Recovery will be conducted during daylight hours only because moorings do not have radio beacons, strobe lights, or other means of location.
• NBP should be prepared to drag for moorings that don't release properly. 9/16" wire rope currently on trawl winch should be sufficient. Drag hooks might need to be fabricated.
• Grantees are providing deck release boxes.
• RPSC will investigate the possibility of adapting their Benthos deck boxes to communicate with Edgetech releases. RPSC will investigate the possibility of hooking Benthos deck release through hull-mounted transducers to communicate with Edgetech BACS 8202 and 8242XS releases. RPSC also will investigate the possibility of plugging the Edgetech deck release (8011A) to a hull-mounted transducer. Karl Newyear will inform AnSlope PIs of results. As of early January 2003 this issue is still being investigated. Communications between EdgeTech, RPSC, and the grantees are ongoing.

Icebregs

• Stan Jacobs has provided information from Don Blankenship regarding the expected keel depth for icebergs B-16 and C-19. The nominal keel depth is estimated at 266 meters. All parties involved in AnSlope continue to monitor the location of iceberg C-19 which is now located in the northern Ross Sea. It is reported that access to McMurdo Sound requires passing to the east of iceberg C-19.

Deck hydraulics

• Plan A: NBP supplies electric power as necessary to an OSU-provided HPU. The HPU powers a traction winch for mooring deployments/recoveries. Line is staged on reels.
  Plan B: If the OSU-provided HPU fails or is not used, NBP can provide hydraulic power to the traction winch from lines on the main deck.
  Plan C: If the OSU-provided winch fails, NBP will have a seismic gun winch and seismic streamer winch available. These winches will be on board anyway, from use on previous MG&G cruises. If either of these winches needs to be used then the gun bundle or streamer will need to be unspooled and stored as appropriate.
• RPSC recommends Plan B to avoid use of high voltage/amperage electricity on deck in possibly very wet conditions. Standard seismic winch operation on NBP includes power provided by deck hydraulics.
• All parties have agreed that Plan B above is preferable. Plan A will be the first backup plan. Jay has forwarded the necessary documentation to Karl. There was insufficient time during the NBP's port call in LYT in early December to plumb and test the winch. However, all fittings, hoses, and other parts are on board and available for setup during the pre-AnSlope port call at MCM.
• None of the three plans for mooring winch hydraulics presents difficulties for NBP systems or capabilities (as per conversation with Jay Ardai on 28 June 2002). Exact placement of the winch and the HPU was left undetermined. Final decisions will by made during the MCM port call. Some considerations:
  - If Plan A is used, RPSC might need to make electrical pigtails.
  - If Plan B is used, AnSlope grantees and RPSC must ensure proper fittings are available.
• The NBP deck hydraulic system provides approximately 2250 psi but this may be lower whenthe system is cold. This is less than ideal for the OSU winch according to information provided by Jay Simpkins. The NBP can provide more than 25 gpm at this pressure, but the flow rate is adjustable.
• It is not anticipated that there are any incompatibilities in hydraulic fluid between the NBP deck hydraulic system and the grantee-provided traction winch.
• NBP deck hydraulics are designed for closed center, open loop winches. If the OSU winch is open center then we can install a valve and either the OSU winch or other deck hydraulics may be used at once. If the OSU winch is closed center then no additional preparations are needed and multiple hydraulic systems may be used simultaneously.
• Jay Simpkins has forwarded documentation to Karl, to the effect that the winch is "closed center, open loop." There was insufficient time during the NBP's port call in Lyttleton, NZ in early December to plumb and test the winch. However, all fittings, hoses, and other parts are on board and available for setup during the pre-AnSlope port call at McMurdo Station.
• Jay has provided a footprint diagram for the HPU and traction winch to assist with a decision on placement on the deck. It is possible that deck plates will need to be used if the equipment does not have a 2' bolt pattern. The final decision on winch placement will occur during the pre-AnSlope port call in McMurdo.