09/02/2009-Wed (JD245)



Gun string 3 partially deployed

Daily Report from Anthony Johnson
090209_V1_DR_MGL.pdf
Gun string 1 remains a problem.  Since it is the outside string, working on this one requires pulling of gun string 2.  It is decided to swap strings on umbilicals, moving gun string 1 to umbilical 2.  This will allow us to pull this string in and out at will until the problem is solved.  When new gun string 2 is pulled in for maintenance, we can use the spares on gun strings 1 (swapped), 3 and 4 and have a total source volume of 5490 (83%).

Lines 17 and 25 are surveyed with gun string 2 providing partial power. After the turn for the start of line 22, gun string 2 fails hard.  String is recovered and RCM is replaced; during maintenance we are 5490 cu in. After maintenance, we are back to full power!

PIs meet during the morning to assign responsibilities for the cruise report and to review the timeline. Science party receives assignments at noon meeting.  PIs meet with Anthony and David at 1400 LT to discuss priorities for shooting plan.  We decide to shoot the remainder of the crustal grid at 5 Kts STW (2.6 m/s).  Shooting on distance (450 m), so shot interval will be about 175 s +/-.  Anthony and David Martinson provide the usual high quality advice and Anthony does some quick and accurate calculations regarding the cruise time line.  As of today, we have time to achieve our objectives, provided we drop MCS line 3 and that the weather cooperates.  However, the 48 hour forecast does not look good, so we are considering our options and priorities yet again.

Current concern is that we are down to 4 GPS (on gun string 4).  If this GPS goes down, we have to stop and repair.

Lines shot
MGL0910_20
Complete survey with 3 strings (2-4) and part of gun string 1.  At end of this survey, gun strings 1 and 2 switch umbilicals.
MGL0910_17
Survey shot with gun strings 1(post swap), 3 and 4.  2 is intermittent.
MGL0910_25
Surveying with gun strings 1, 3 and 4 and part of 2
MGL0910_22
Gun string 2 was pulled while on-line and repaired.  Finished this line with full source.