Appendix 2: Service of the
University of New Hampshire, Open Ocean Aquaculture Program's Moorings and Fish Cage with the FV Nobska
19-23 June 2000
James D. Irish and William M. Ostrom, Woods Hole Oceanographic Institution,
Dave Fredriksson, University of New Hampshire
Goal: The goal of this operation was to combine WHOI and UNH mooring expertise with the FV Nobska to service the UNH Open Ocean Aquaculture moorings and fish cages, concentrating on the northern cage.
The present condition of the northern fish cage and mooring as illustrated above was assembled as a best estimate of its status from surveys by UNH divers.
Tasks for WHOI and the FV Nobska:
Chart of the Isle of Shoals Region. The fish cage was moored about the "i" in White of White Island, and the UNH Aquaculture site is the bottom of the chart in the center.
Monday - 19 June
1230 - FV Nobska at WHOI pier. Deck boxes, fish cage mooring, load cell support, etc. loaded and secured for transit to NH. Will Ostrom will ride ship up.
1330 — FV Nobska departs WHOI dock to NH via Vineyard Sound.
Tuesday - 20 June
~0300 Nobska arrives Isle of Shoals site and waits for the Gulf Challenger.
0530 — Irish meets the Gulf Challenger at the NH State fish pier with the UNH crew.
0545 — Nobska departs fish pier for OOA site.
0615 — Personnel transferred to Nobska and a review of operations plan. Nobska has Will Ostrom and Jim Irish from WHOI and Barbaros Celikkol, Paul Lavoie and Dave Fredriksson from UNH. Michael Chambers and divers are aboard the Gulf Challenger with the UNH film crew.
0720 — Start work. Nobska retrieved lifting line with bridle attached to the northern fish cage counter weight installed by UNH divers on Friday (See Figure 1). The Nobska pulled the weight to the surface by winding the recovery rope up on the aft fish drum until the anchor was at the stern. Then the port winch cable was run through the port gallows and shackled to the anchor. The anchor was then picked up out of the water and held on the rail (see photo P001161 below). The tether to the fish cage was released and UNH personnel in an AVON inflatable boat took the tether back to the fish cage and secured it so it would not interfere with future operations. The counter weight was then transferred to the Nobska 's boom and secured on deck amidships for transit. Matt Stommel estimates that the weight was greater than 6,000 lbs. by the pull on the winch and crane, but the counter weight was not weighed. While this operation was being done, Irish with help from Fredriksson set up a GARMAN GPS receiver and notebook computer to log data on ship's position and speed over the ground, a Synergetics data system to digitize and a notebook computer to log data from the load cells. The load cells were attached to the data system and set on the 01 level deck for zeroing so the electrical cables were out of the way on the main deck for operations. Dave Fredriksson set up a Marsh McBirney electromagnetic current meter to obtain velocity measurements of the ship relative to the water.
0800 - Nobska picked up the crown line marker buoy "A" and relaxed the grid until the steel grid floatation balls were observed on the surface. The fish cage floated with a marked tilt (see photo P001166 below).
0820 - Releasing the fish cage. The grid line from anchor "D" was grapneled off the stern. A second grid line was hooked along with this line, and was seen to be running under the fish cage. This line was cut as we weren't sure where it ran or how to untangle it. When the line was cut, a heavily fouled steel grid corner buoy was seen to surface that might be the missing buoy and line to anchor "B"! Then the cage was detached where the bridle lines attach to the riser line. The Nobska moved over to the other side of the fish cage and detached the bridle lines from anchor "A" to the riser line. These were attached to the Nobska's two steel winch lines going through the gallows blocks.
Figure 1. WHOI design of the recovery bridle for the fish cage counter weight.
0900 - The fish cage was then towed out of the grid. However, it didn't clear the buoys before we were hung up. Divers from the Gulf Challenger determined that the lines from anchor "B" were still attached to the fish cage, and they unshackled these lines and the Nobska was able to pull the cage free of the moorings.
1000 - The poly tow lines supplied by WHOI were attached to the 1-inch bridle lines on the fish cage, and the cage dropped back of the Nobska. The ship stopped and the load cells were placed between the poly lines and the ship's steel winch cables. The electrical cables from the load cells were run to the data system on the bridge that supplied switched battery power to the load cells, and digitized the resulting signal.
Photo P001161 - the northern fish cage counter weight being recovered by the FV Nobska.
1010 - The slowest the ship could go was about 1.5 knots, and a first point was taken here. Dave Fredriksson on the main deck used a Marsh McBirney electromagnetic current meter to get the speed of the ship relative to the water. The GPS log gave the speed over ground and the data system gave the output of the load cells. Log files were made of all data for later analysis. A drift test while the Nobska was waiting to connect with the cage indicated currents less than 0.1 m/s in the region.
1013 - The ship started a turn toward the mooring site, the load cells show a shift in tension between the two cells. When steaming straight, the tension was nearly equal. The fish cage towed with the rim at the water line, and the back of the rim underwater (see photo P001172 below).
1015 - speeded up to 1.7 kts
1017 - speeded up to 1.9 kts. A quick back-of-the-envelope calculation showed that at 2.0 kts speed (relative to the water via EM current meter, or 1.9 kts via GPS over the ground), the tension (sum of both load cells averaged over six 5-second readings) was 6,150 lbs. A very reasonable number considering the cage was half out of the water and the fish net in the water was heavily fouled with mussels.
Photo P001166 - the fish cage after the counter weight was removed and the grid relaxed. The cage floated with a marked list to one side.
1023 - End of test and load cells were taken out of towing line. The fish cage was then towed toward the hi-flyer maker deployed by the Gulf Challenger between Lunging and White Islands. As the Nobska drew abreast of White Island the tow velocity dropped as a strong current against us was encountered. It was decided that the cage was in a good position (11 fathoms depth) so we would anchor the cage there. A plan of the cage mooring is given in Figure 2 below.
1112 - The anchor with line and float (See Figure 2) attached to the fish cage were deployed. The anchor was released with the fathometer reading 12 fathoms while the fish cage was in 11 fathoms. The Nobska then returned to recover the northern fish cage anchors while the Gulf Challenger worked on the fish cage.
1230 - Starting recovery of the cut anchor and crown line "C."
1310 - steamer chain wrapped around anchor
1400 - anchor on deck and cleaning up. The Gulf Challenger not having much luck, so Nobska will not plan on towing/carrying the spar to Portsmouth today and will fill deck with anchors, buoys, etc. By the barnacle growth and rust patterns on the anchor it was determined that this anchor was upside down, that is with the fluke in the water rather than in the bottom. Going for the northwest anchor with spar marker buoy - "A."
Photo P001172 - Nobska towing the fish cage. The red poly lines are visible, as well as the bridle lines at the fish cage. The load cells were coupled in at the lower edge of the picture where the shackle is visible. The fish cage towed easily with the front edge of the rim just out of the water.
The end of the cut anchor line was retrieved with the mooring "C" and was inspected. It looked as if about 3/4 of the line was cut cleanly with one cut, and that there were at least two more lesser cuts in the remaining fibers (See photo P001272 below). There is the possibility of cutting the rope with the anchor during deployment or more probably during relaxing of the grid if the anchor was lifted off the bottom and carried too far toward the cage. The cut was clean and probably not caused by a fisherman dragging it aboard. This is an interesting mystery that we may be able to further study by examining the cut end. The end was bagged in plastic to protect it from picking up other dirt and materials from the ship and pier.
1420 - Spar "A" aboard and being disconnected. Chain length adjuster not really used and hanging as a weight. Suggest that this be removed to reduce wear of chain on crown line.
Figure 2. WHOI design and component lists for temporary cage mooring.
1440 - winding crown line on aft fish reel.
1510 - at small chain at anchor. Anchor is also fouled with steamer chain wrapped around it. Chain cut with torch to be able to recover (See photo P001189 below).
1630 - anchor all aboard and steaming for Portsmouth while pressure washing and hosing off buoys, lines, etc. By barnacle growth and rust line, it appears as if this anchor was also upside down, fluke in the water rather than in the bottom. This anchor was not dragged around and may be an indicator of a problem with the anchor deployment method used previously or the tensioning and relaxing of the mooring during the past year. The weight of the large amount of steamer chain acted as a good anchor to help hold the fish cage in place.
Photo P001272 - The cut end of the anchor line. There is one main cut most of the way through the line seen at the left. Another cut is visible just to the left of Walter Paul's finger, and at least two more cuts at the far right. The cuts were clean indicating that it was not torn apart or cut by rubbing against a rusted wire rope.
1730 - at Port Authority pier and tying up for the night by the large cranes for ease in offloading in the morning.
Photo P001189 - Mat Stommel (left) cutting chain wrapped around anchor while Will Ostrom (right) keeps water on line so that sparks from the cutting torch will not burn line holding the anchor chain for recovery on the aft fish reel.
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Wednesday - 21 June 20000
0630 — Nobska at Port Authority Pier. Crane operators on hand. Michael Chambers there and discussing plan of action for day. Nobska will unload and then proceed to pull remaining anchors. Gulf Challenger will work on removal of fish net. Matt Stommel suggested that the net might be tied and dropped to the bottom with marker buoy for the Nobska to recover and wind on their aft net reel.
0730 — Started offloading operations using (See photo P001254 below) and large Port Authority cranes. Poly and Steel balls first, then the anchor, counter weight, lines and finally chain were unloaded. The chain was stretched out on pier by Port Authority forklift. Most of Dave Fredriksson's tags marking which piece came from which mooring remained in place.
0845 — Done offloading moorings "A" and "C" (western two moorings) and departing Port Authority Dock for site to recover moorings "B" and "D" on eastern side of Northern site and to tow in the fish cage.
1000 — At the northern fish cage site, weather calm with light winds. Three sets of surface floats visible implying that we may have the marker buoy for the northeast anchor "B" which we thought might not have a marker and we would have to try and drag for it. Decision was made to recover the Norway ball on down-wind end of the series of buoys and see what we have. Picked up the marker and the steel grid corner buoy. Grid corner with lines present brought aboard. One lower bridle line and two grid lines attached to corner. Also anchor line. One bridle line retrieved that was freshly cut (This was the line recovered and cut by the Nobska when servicing mooring yesterday as it ran under cage.) It is probable that this got tangled under the cage and mooring so was not seen and identified earlier by the divers. The lines going down seen by the divers were probably the lines from this mooring leading down under the cage where they were tangled. This line was heavily fouled with about 18-inch diameter of mussels. A second grid line lead to another anchor and so was buoyed off with Norway ball float marked "UNH." A full lower bridle line was recovered with shackle at far end with pin missing (assumed removed by UNH divers). All lines were fouled with heavy mussel growth. Grid corner was broken out of lines and anchor line attached to aft drum.
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Photo P001254 - Port Authority crane offloading gear from the Nobska on the 2nd morning.
1020 — pulling on anchor line on aft drum, winding up line (See photo P001178). Less mussel fouling.
1030 - pulled anchor line up to steamer chain. It is obvious that the anchor is off the bottom as the Nobska is now drifting downwind toward White Island. Again the torch was used to cut the shackle between the chain and anchor line.
1050 — cut 2_ inch anchor chain so can wind on aft drum (see winding operation in photo P001223 below). Got anchor up so can see that chain is fouled on anchor again. The wind is up significantly — a few white caps — wind speed is estimated 15 kts.
Photo P001178 - winding the mildly mussel-fouled anchor line on the aft net reel.
1120 — anchor at rail, working with anchor to untangle chain. Cut chain off anchor to get on board. Cut chain on both ends of anchor.
1135 - winding in crown line chain. Got entire crown line to the buoy and another two-color (black and yellow) poly line was wrapped where spar buoy should be. It appears that the 3/8-inch bail on the buoy broke as the mooring shackle was present.
1140 — anchor at rail recovering.
1150 — anchor on deck. Drifted almost up to White Island. Gulf Challenger says that they will be ready for Nobska in just over an hour, Nobska will proceed to recover last anchor and mooring.
1210 — getting the downwind part of anchor — pick up poly float up stern ramp.
1215 — grid corner and buoy aboard. Breaking buoy off. Wind up to ~20 kts.
1220 — winding bridle line from polyethylene ball to polyform float on aft reel. Grid line on central reel from polyethylene ball and a second grid line on second polyform float and then lower bridle line to polyethylene buoy retrieved ok.
1235 — wrapping anchor line up on center reel.
Photo P001223 - winding the 2_ inch stud link anchor chain on the aft net reel.
1250 — Recovered mooring to anchor chain. The Nobska had a problem pulling the anchor out of the bottom. However, we just waited and let the waves gently work it out.
1300 —Cutting off shot of chain on last anchor. Anchor here was also fouled in chain. It should be noted that all four of the four anchors recovered at the northern cage were fouled in their 90-foot length of 2_-inch stud link anchor chain.
1310 — Gulf Challenger done and starting to tow spar to Portsmouth. Nobska will pick up net and follow with rim when done.
1330 — recovered crown line. Broken at buoy attachment point again.
1400 — moved away from land so we wouldn’t hit the lighthouse. Starting to recover anchor with chain wrapped around it. Gulf Challenger doing well with tow to Portsmouth. Plan on offloading tomorrow morning 0800.
1425 — chain all aboard — cut off anchor
1430 — anchor aboard and securing. Heading for net and rim. Only one Norway ball on net.
1500 — net aboard OK - wrapped up on aft reel in less than two minutes (see photo P001240 below)
Photo P001240 - winding the northern fish cage net onto the Nobska aft net reel. The whole operation from pickup of the buoy to net wound upon the net reel took about two minutes.
1515 — planning recovery and starting for yellow can to pick up rim tow.
1535 — towing rim on the 1 inch polyester bridle lines to the Nobska's two winches with steel cables through the gallows blocks. The rim was towed fairly close to the boat to lift the front edge of the rim so it could not dive down into the water. Rim towing fairly nicely at 3 to 5 kts. (See photo P001244 below).
1550 — 6.7 kts — noticed normal mode oscillations in ring so slowed down to 5 kts.
1600 — about 5.2 kts speed over ground for rest of tow.
1730 - arrived at Port Authority pier and tied up Nobska downriver from the spar. The rim was tied with two lines - one to the Nobska and the other to the dock to prevent the rim from hitting the Nobska or going under the dock. The rim was floating level with water like there was no major leakage in any one rim section. This was encouraging as it was thought that at least one of the rims had leaded and not providing sufficient buoyancy.
Back to the TopThursday - 22 June 2000
0800 - Offloading the Nobska with second deck load of anchors, floats, lines, etc.
0900 - The Nobska will to return to the OOA demonstration site to repair the crown line floats "E" and "G" of the south cage system. Two polyethylene floats, an extra crown line, an anchor line, and a spar 1-inch adjustment chain was loaded aboard for spare material in case any component needed replacing.
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Photo P001244 - Towing the rim at about 5 kts with Star Island in the backgound.
1000 - (approx): Arrived at the demonstration site and recorded GPS position of the crown buoys "F" and "H."
F - 42o 56’ 36.6" N x 70o 37’ 48.0" W
H - 42o 56’ 28.8" N x 70o 37’ 48.0" W
1100 - Start at crown line "G." Pull the existing spar buoy without light or radar reflector aboard the Nobska and detached it from the mooring. Attached a polyball with 5 feet of _ inch chain. Also attached to the polyethylene float was a tag line connected to a small Norway ball for ease of recovery when the Gulf Challenger replaces the polyethylene float with a permanent marker buoy.
1230 - "G" marker buoy replacement completed. New buoy positioned at 42o 56.478' N x 70o 37.922' W. When the Nobska was ready to drop the new crown buoy overboard with the crown line coming pretty straight up from the anchor and steamer chain, the anchor line was visible on the 's fish finder about 9 feet above the bottom. This implies that the Nobska had dragged the crown line back over the anchor (which she was trying not to do) or that the 90 feet of steamer chain was wrapped on the anchor and shortened the distance to the anchor line. The fish finder transducer was located about 50 feet forward of the aft deck where the marker buoy was being held ready to release.
1245 - Begin dragging for missing crown line at "E."
1330 - Grapnel caught on stud link of anchor leg between anchor and anchor line.
1400: Begin the process of pulling up sections of anchor and crown line components cutting as needed.
1440 - Reconnected pieces of chain with shackles with pins welded and redeployed. Crown line polyethylene float deployed with 15 m of _ inch chain and Norway ball. New position at 42o 56.6' N x 70o 37.926' W. When the anchor was pulled out (taking care not to tangle the steamer chain) the crown line buoy was extended farther than the other buoys from the cage. This may be further indication that the other anchors may be fouled. The Nobska had difficulty in deploying the anchor system without fouling. It is clear that the anchor must be lowered by the crown like to orient the anchor properly. We also suggest that UNH check the depth of the buoys and tensioning of the south cage before stocking with fish.
Also, the fact that this mooring was deployed with care to keep the mooring from tangling, and that the other mooring serviced gave indication of being fouled in its chain, it is suggested that a side scan survey be done to see if the other anchors are fouled, and we might consider retrieving and resetting the rest of the anchors on the south cage to assure they are working as designed. However, as the moorings haven't moved much due to the weight of the chain and anchor, it would be for reasons of wear and component damage that this should be considered.
When operations were completed, Dave Fredriksson (the UNH crew) and the spare parts (lines, shackles, etc.) brought along in case the Nobska needed to service the anchor or crown line, were returned to the Port Authority pier. And the Nobska headed for Woods Hole with a stop in Cape Cod Bay for another anchor retrieval for another project.
Back to the TopFriday - 23 June 2000
1330 - Nobska arrived at WHOI dock and dragging gear, deck boxes, temporary cage mooring hardware, etc. were unloaded.
1530 - Nobska heading for berth and UNH OOA operations complete.
Back to the TopSummary of findings:
Photo P6220006 - Anchor from leg "A." The mud line is seen just down from the top of the shank on the anchor on the top right.
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Photo P001196 - Anchor from leg "C." The mud line is clear on this as the dark line running up the anchor shank, indicating that this anchor was also upside down.
Photo P001259 - Anchor from leg "B." The mudline can be seen about 1/3 of the way up the anchor fluke indicating that the NE corner anchor was not fully embedded in the mud.
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Photo P001258 - Anchor from leg "D." This anchor was fully embedded and the mud line can be seen running forward from where the crown chain attaches to the anchor.
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Photo P001287 - Anchor line shackle from leg "B." This is the most warn component in the northern cage mooring system. As expected, it was in the NE corner where the steamer chain attached to the anchor line. The pin (in the shadow on the left) is also worn. The bending of the two jaws of the shackle was done during the recovery operation.
Back to Appendix 1: Marking of Mooring Components
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