USNS Sioux Supports MDSU Dive Operations off the Coast of San Diego

Off the coast of San Diego, Calif., Military Sealift Command’s only Pacific based fleet ocean tug, USNS Sioux (T-ATF 171) is supporting dive operations with the Navy’s Mobile Dive and Salvage Unit ONE (MDSU 1), providing a training platform for the divers and the tug as well.

Throughout the month of April, Sioux has been moored in a variety of areas and scenarios off the San Diego coast. While the mission objective is to provide a dive platform for MDSU divers, the situation offers a training opportunity for the crew of Sioux.

“When we do missions like this, we get to interact with the MDSU divers during the training, so if we have to support a mission later on, we have a better understanding of how they do business, because we worked with them in a controlled training environment,” explained Capt. Harry Sprague, Sioux’s civil service master.

Providing a platform for dive operation is more than traveling to a dive area and dropping anchor.  Much of the diving support occurred over the sunken Canadian Mackenzie Class destroyer HMCS Yukon (not related to the MSC ship USNS Yukon.) One hundred feet above the sunken ship, Sioux encounters heavy current and sea states, especially in Southern California, that the crew must compensate for.  Ship handling skills are put to the test, and it becomes a unique training platform for young officers who must monitor depth, mooring and steering of the 225 foot Sioux.

“This is a really good learning opportunity, especially for new mates coming up through the ranks,” said Sprague.  “It takes a lot of seamanship to do DIVEOP support.  When you are diving over a wreck, you have to position anchors over the sunken ship in a certain way so you don’t drag the chain and foul the anchor.  To be successful, you really need a lot of pre planning, ship handling and seamanship.”

In addition to ship handing planning, the crew must monitor consumables on the ship.  With DIVEOPS come extra people onboard the ship.  Divers, observers and support crew mean extra people requiring berthing, but also potable water and food.  Coast guard requirements and documentation mean each person onboard needs to be documented on the excursion permits.  All of these issues must be monitored and test the attention to detail of the crew.

At the start of each week, Sioux traveled to the dive site for that week.  On the first day, the crew and the MDSU divers conducted debeaching operations.  As a fleet ocean tug, Sioux’s mission parameters outline the mission of the ship as towing and salvaging of ships.  This includes removing vessels from shallow areas such as reefs. According to Sprague, these operations require very detailed movements, mooring scenarios and ship handling skills; skills that test engineering abilities. Like the DIVOPS training, these debeaching exercises prepare the ship for real world missions in a variety of conditions and sea states.

While all the operations conducted over the month of April are training operations, there is still a great deal of real world stress for Capt. Sprague and his crew.  In a controlled environment, things can still go wrong, so tensions are high, but Sprague says he thrives on the pressure.

“For me that’s the fun part; the stress” he laughed.  “I try to keep the stress level, on the bridge down and things calm, so my crew is calm and able to perform.  I also encourage them to learn as much as they can.  My motto for them is, ‘If you’re not working, you’re watching and learning.’”

Following DIVEOPS support this week, Sioux will return to Naval Base San Diego.  The ship will join other MSC ships in Hawaii in July for the bi-annual, multi-national maritime exercise, Rim of the Pacific 2018.

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