Category: ru29 (Page 3 of 22)

Now less than a week away from when the team will arrive in Cape Town and set sail to recover Ru29, we continue to fight the oceans currents as we look for the best way to get the glider closer to shore.

On Tuesday, 29 was given a new way point and almost immediately we saw a change in the direction of the currents as they rotated from West to North-West, and as the week continued this rotation moved further and further north.

A reduction in the number of yo’s per segment also led to a decreased number of oddities from the pump.  As of last week, the pump was holding steady at 32 oddities; we reduced the yos by 25%, so we would expect the oddities to then drop to 24.  However the result was 19, so 19/24= .79 so they effectively dropped by 21%.  The more well behaved pump has also lead to the power usage dropping back down a bit allowing the team to rest a little more easily.

By Wednesday, the persistant West North-West current had slowed Challenger down to a crawl of about 1 km/10hrs while the glider continued to try and push east to the cold core eddy.  It seemed though that the warm eddy in the image above had shifted and the northern edge was what was causing the strong westward current.

Antonio however suggested we move the waypoint to the North East of the glider citing the Copernicus salinity data overlayed with the current fields.  The water that spills over from the Indian ocean into the South Atlantic is significantly more salty and shows up very nicely in the data:

Copernicus Depth Average Current with 260m Depth Salinity

With the new waypoint set to 32º30`S, 14º30`E, Challenger regained some pep in her step as the currents rotated further to the north and she covered a significant distance compared to the progress made over the past few days

With this change of luck we will keep Antonio’s way point and see if we can continue to make better progress while the recovery team makes final preparations for their travel to Cape Town

Force Wind Sea & Honor

The image above shows that RU29 is about 95 kilometers from South African waters. However, the currents are the wrong direction flowing more west than anything else. And it is hard to rely on what the glider is reporting.  The waypoint is northeast, the reported currents are mostly west, even when you account for the persistent difference in magnetic versus true. Yet the glider is traveling slowly southeast.  The following are todays forecast products

Oscar Mar 21

OSCAR says if we can just get a bit more east, we will begin to feel that large cold core eddy that will bring us around clockwise into South African waters.  That means we should soon see currents to the north. Dave’s suggestion of flying ESE will aid in getting us there.

GLOSEA Mar 21

GLOSEA agrees with the OSCAR forecast, also showing the large cold eddy to the south east.

HYCOM Mar 21

HYCOM says we should have had a favorable current to SE that last few days, and we did not. It also says if we fly south, we will enter a current to the west. But we are already in a current to the west – our present issue. HYCOM further says that if we continue east, we will find ourselves in a strong southward current, the exact opposite of OSCAR.

RTOFS Mar 21

RTOFS is showing the same as HYCOM but with slower currents. ROTFS does however start with the same initialization as HYCOM, but uses different winds to complete the forecast.

So we have two products saying we should go ESE, and two products saying there lies danger. The Copernicus product however is not yet available for a tie breaker on the guidance side as they are in the process of doing maintenance on their site.

Despite what the models are saying, Challegner is telling us East North-East is not working, and that straight East will not work.  29’s track is telling us to try ESE to see where it gets us regardless of the guidance.  Hopefully the model guidance from OSCAR and British are more correct.

For the gliders status, the power plots have to be adjusted.  We are up to about 3.2 AH/day, and down to about 50 days left.  That is end of April/early May if nothing else happens, like the need for shallower dives or more pump leaks.  Luckily we are all set to recover in just over a weeks time.

Communications and steering are holding steady, but the oddities and pump issues on climbs outlined last week are still the main problem and the source of the increased power draw.  At some point this week we would like to try and pull more data from the glider to see if there is anything that can be done, however that would require a more prolonged surface time and at the moment we are in a pretty high trafficked area

Force Wind Sea & Honor

105 km to South African Waters, and Challenger is looking like she is ready for a very well deserved rest.

Lagrangian Flow Map using Copernicus Forecast Data from Antonio Ramos

The reported currents are 19 cm/sec to South West, but the glider is flying South East – our East-North East waypoint is still having a significant influence, even when the direction is corrected from the magnetic to true north rotation.

Recently the power consumption has skyrocketed to 3.25 AH/day compared to 2.1-2.2 AH/day during majority of the mission.  At this rate,  the power consumed over the course of a day is worth 1.5 days from early in the mission.

This we believe is largely due to the pump slipping and having to repump throughout the flight rather than moving to one position per dive or climb.  Lately segment oddities are up to 30 per segment as the pump has been all over the place having to pump multiple times on climbs through the water column.

Steering holding steady at 15 degrees rms. Constant offset of +5 degrees with Fin offset partially compensating at roughly -7 degrees.

Comms back to good after a small bad patch.

The waypoint for now seems to be doing well keeping us on a path with Eastward Progress.  Below is a current map comprised of the average output from the Five Forecasts we have been taking into account for piloting.

5 Forecast Average Output

oscar – head east, not too much south, perhaps a tad north, if we take turn too tight we could go west or if we come in hot into the eddy we we might not get back out.

copernicus – head E, shows route to the south isn’t too great as the eddy we’re trying is moving west quickly.  also too much north could put is in an unfavorable eddy to the north

Copernicus Mar 18

HYCOM – head ENE and fast or else we find west currents again

HYCOM Mar 18

GLOSEA – says were ok just keep heading east

GLOSEA Mar 18

And finally RTOFS has us also in the midst of a south east current that we must continue to try and make our way east across.

RTOFS Mar 18

Force Wind Sea & Honor

Now just under 140km from the South African EEZ, Challenger continues to fight her way through currents pushing to the North and West to make progress towards shore.

Through the weekend the glider continued to pursue the way point set on Friday and after a few surfacings, Challenger made a steady turn to the east and has progressing in that direction since Saturday afternoon.  However, the change in currents doesn’t seem to be reflected in any of the models.

OSCAR March 14

The latest run of OSCAR says that there will soon be a current to the south, however has the current in the immediate area pointed south west while the glider is reporting currents to the North West.

Copernicus March 14

Copernicus shows a similar field ahead of us, however it has the glider already in the southward current again contradicting what the glider is reporting.

RTOFS March 14

GLOSEA March 14

HYCOM March 14

HYCOM, RTOFS and GLOSEA all are similar today in showing that there is a weak current immediately ahead of Challenger and so after looking at the 5 models we will keep the waypoint in the same spot for now and hope the eastward progress continues.

As for recovery preparations, we are continuing to work on locking down the Algoa as the recovery vessel.  The ship has room for 16 passengers and so far the Recovery Crew is as follows: Scott Glenn, Josh Kohut, Travis Miles, Chip Haldeman, Dave Aragon (RUCOOL), Rick Ludescher (RU Dean) + Andrenette & Cassidy (2 students). Lizette + Partner (film crew from RU27). Ben Allsup (TWR) Marcelo Dottori (USP), and Antonio Ramos(ULPGC)

Force Wind Sea & Honor

As we head into the weekend Challenger looks like she is encountering the cold core eddy sitting to the northwest.  Over the past three surfacings, the speed of the currents have steadily increased from 17 to 18 to 22 and rotating to the south west simulating the glider entering the south east sector of a cold core eddy.

To try and combat this westward flow, the glider was just issued a new way point to the East North-East at -33˚ S 14˚ E to pursue over the next few surfacings

Force Wind Sea & Honor

The currents reported by RU29 have rotated to northwest, but the good news is they are still relatively small at about 11 cm/sec.

RU29 is making good progress in these conditions, using her speed to push east.
If we keep this track, we enter the South African EEZ on the northern side of an Agulhas eddy lying just inside the EEZ that carries us even closer to shore.

OSCAR Forecast Mar 9

First current map is from the OSCAR product showing we are in a very low flow zone that extends to the EEZ.  As long as the flow is low, we are good with the direction error we are currently seeing in OSCAR locally.

Copernicus Forecast Mar 9

Second current map is Copernicus, the most reliable product of the entire trip.  Copernicus says we are crossing the middle of a strong jet to the Southwest. It is clearly wrong about the jet.  Currents are weak to northwest.

HYCOM Product for previous week

Third map is HYCOM, the newcomer to the mix.  It is in very good agreement with the observed currents by Challenger. HYCOM says there is a small area of slow currents on our way to South Africa, and we should stay about this latitude since if we go south, we encounter a strong current to the west.

HYCOM Forecast Mar 9

Fourth map is the HYCOM forecast, showing the jet to our south is forecast to strengthen.
It is nice to know this forecast, that if this jet is true, and if we somehow drift south,
we may encounter a current that opposes our progress.  if we do encounter this current, we would try to fly back north to get out of it and back into the calm water. But right now with the northward ocean currents, and keeping RU29 focused on east, the likelihood of us drifting south into this current is low.

Historical Vessel Traffic

Finally we have the historical vessel track data that outlines the path ships have taken over the past couple of years. The glider is currently flying through an area that is more heavily trafficked and so we will try and keep surface time to a minimum to avoid being struck by boats.

Force Wind Sea & Honor

Now within just 130km of being in range for recovery out of Cape Town, Challenger is continuing to fight her way through the dynamic eddy field around the cape.

Through the weekend, the current seemed to be dying down while still flowing northward shown in the image above of the currents reported by Challenger matching the output from OSCAR.

With the waypoint set 150km to the east, we aimed to continue our East North-East progress while approaching the cold core eddy nestled right inside South Africa’s EEZ.  This eddy we hope to catch within the next few weeks to draw the glider closer to shore when we are ready to conduct recovery operations.

This morning we had a call with Seb from South Africa to try and forge a plan for recovery.  From the call, we decided the best boat to aim to get was the RS Algoa (https://www.fleetmon.com/vessels/rs-algoa_7410369_2546/?language=en), which is a South African research vessel which has a zodiac, ctd and plenty of births on board to accommodate the recovery team.

The goal is to recover the week of March 28th, arriving in Cape Town on Tuesday of that week and spending roughly 2 days at sea steaming out to the glider, recovering and returning to shore.

Piloting wise, we will continue to fly 29 east towards shore with hopes of getting within South African waters with roughly a week to maneuver around as the team arrives and steams out to the recovery location.

There is also a team of South African scientists on stand by that are willing to jump out in an emergency scenario to recover the glider if anything happens before the end of the month

Force Wind Sea & Honor

To kick off the week, Challenger was given another waypoint close by to the East North-East in hopes that we can turn the glider and avoid the large eddy threatening to bring the glider way to the North.  The waypoint also aims to keep the glider in the nice pocket of low ship traffic to reduce the chance of being struck by a boat while at the surface.

The pump also continues to have some issues as the team is now tweaking pitch angle and the deadband on the pump to find the ideal setting that gets the glider flying faster while getting less oddities or errors.  To also try and reduce the stress on the pump, the dive depth was reduced again to 500m.

OSCAR March 2, 2016

By mid-week, it was time to move the way point further east to try and avoid the eddy to the north. The OSCAR model seemed to agree closest to what the glider was recording, so we moved the way point to try and steer 29 into the weaker area of the current shown above in wednesdays product.

Finally, Dave plotted 29s power consumption and compared it to the mission from Cape Town to Ascension and found that according to the curve, we may only have about 60 days of power left giving us to the end of April to get the glider out of the water.  With this new press for time, Dave and our friends down in South Africa have started searching for boats we can try and charter as recovery vessels as we now want to recover as soon as we can.

Force Wind Sea & Honor

Starting off on Friday afternoon, Challenger was given a waypoint to the North East.  The glider was entering an area of weaker currents so we were trying to capitalize on that and try and make as much eastward progress as possible while we had the opportunity.

The currents remained weak but variable through Friday into Saturday, however by Saturday night, the currents rotated back to the west, once again slowing 29s progress towards South Africa and forcing the gliders path to curve back to the north as she was unable to over power the current.

Also over the weekend, we stepped the depth at which the glider dives to further down to 600m in an attempt to damper the growth of creatures on the hulls of the glider and to better fight the current.  The pump which has been problematic throughout the mission though didn’t react well to the deeper dive depth and began slipping again resulting in increased power consumption.  Because of this, the glider was commanded back to flying to 550m in hopes that the pump will return to normal behavior.

Force Wind Sea & Honor

Through the week, Challenger continued to persue the waypoint to the north east.  Looking at Copernicus forecast, we hoped we could snake 29 up and around the cold eddy to our east and start making progress back towards Cape Town.

On Tuesday after seeing RTOFS/HYCOM we’re performing the best capturing an eddy to the immediate west that matched the curvature of the gliders reported currents, the way point was moved way out to the north east in order to avoid being dragged west as we reached the northern edge of the eddy.

We also commanded 29 to start diving deeper by 50m (to 550m).  The glider is now seeing over 20% biological growth which has affected our steering and slowed down the glider.  In order to combat the growth and to try and dive below the currents that are proving to be too variable for the models to accurately portray them, we are going to start diving 50m deeper at a time in order to acclimate the pump to diving past 500m again.

Finally as the week wraps up, Challenger was able to break away from the eddy that was threatening to drag her further west, and began making progress east in the absence of strong current.  Hopefully this will last as Challenger makes her way towards Cape Town.

Force Wind Sea & Honor