The Hawai'i Undersea


Current status: At present HUGO is not operational.

Update: October, 2002:

HUGO was recovered using JASON on the T.G. Thompson in October, 2002. 
The cable was cut about 3 m in front of the Junction Box, and a lifting bale attached 
to the hard-back. There are currently no plans to re-install HUGO. The rough terrain 
of the volcano would likely destroy any unarmored cable, and armored cable is not 
available without considerablecost.  The Junction Box is in excellent shape, and will
likely be used in another observatory.

The HUGO Junction Box October, 2002 before recovery   			 Attaching the lifting bale			 Getting ready to cut the optical cable to shore

 The Woods Hole JASON II team and the recovered HUGO Junction Box

Update: November, 1998:

The Submersible PISCES V attached a battery pack to the HUGO Junction Box in the port where the Shunt Regulator would normally attach. The idea was to see if the Junction Box and fibers in the cable were still operational. The Junction Box and hydrophone came on line as expected, and about 8 hours of high quality high-rate hydrophone data were obtained at the Shore Station at Honuapo through the cable before the battery pack was depleated. This was the olast operation of HUGO.

Update: April 29, 1998:

On Friday, April 24, 1998, HUGO was brought up without problems on a new Shore Station Power Supply, after being down for about a week because of a bad power supply.

On Sunday April 25, however, Bob Jordan was unable to bring the HUGO system back up after a crash. Electrical current to the Junction Box on Loihi was too high. On Monday, it was determined that the diode in the Junction Box which prevents current from flowing in the wrong direction was no longer active, and current increase with voltage implies an electrical short to sea water. The leak to sea water is either in the cable or in the Junction Box.

Today, Dan O'Conner brought an OTDR from Honolulu to the Shore Station at Honuapo to test the five optical fibers that are connected between the Shore Station and the Junction Box. All fibers test as being intact, so we at least know that the cable is not completely broken. The fibers are buried in the center of the cable, so it is likely that the poly insulation could be damaged, causing an electrical short, without degradation of the optical properties of the cable.

CURRENT STATUS. HUGO is down with no chance of coming up again until this fault is repaired or replaced.

ACTION TO BE TAKEN: The first step will be to determine whether the short is in the cable or in the Junction Box. Unlike coaxial cable, the HUGO cable is an unshielded single conductor with a sea water return, so a time domain reflectometer to determine the distance from the Shore Station to the fault will not work. We will discuss the problem with AT&T engineers to see if there may be another way to determine the distance from shore to the fault.

To determine whether the fault is in the Junction Box or in the cable, we currently plan to plug in a temporary battery power supply into the shunt regulator connector at the Junction Box during Pisces V dives this fall. If the Junction Box is intact, and the fault is in the cable, the Junction Box (diode isolated from the cable) will come up, and data will be sent to and from shore through the optical fibers in the cable. If the fault is a leak in the Junction Box, then the battery supply will draw too much current and blow its circuit breaker.


  1. If the fault is in the cable, we could run a second (electrical only) cable from shore to the Junction Box, and still use the fibers in the original cable for data transmission. The HUGO Junction Box was designed to accommodate this possibility.
  2. If the fault is in the Junction Box, then we can recover the Junction Box for repair. We would also recover the end of the cable and terminate it with a connector through which the optical and electrical status of the cable could be tested, and to which the Junction Box could be re-connected at a later date.

Both of the above options are costly, although considerably less costly than starting over from scratch.

We will continure to reduce existing data until we're caught up and soon expect to post the varied sounds from Loihi on the HUGO web page.

Fred Duennebier