Friday, December 5, 2014

Jensen Maritime Designs New ASD Tugs

By Mark Edward Nero

Jensen Maritime, Crowley Maritime Corp.’s Seattle-based naval architecture and marine engineering firm, said Dec. 2 that it is providing designs for two new Azimuthing Stern Drive, 5,360 horsepower tugboats for New Orleans-based Crescent Towing.

The designs are based on Jensen’s existing 92-foot ASD tug design. The tugs are the fourth and fifth vessels Jensen has designed for Crescent, with the most recent design having been delivered in 2010.

“The high horsepower and compact, deep-draft design of the 2010 tug allows us to better serve a wide variety of our customer’s current and future needs,” Keith Kettenring, Crescent Towing’s executive vice president, said in a statement.

Improvements made in the new designs are expected to yield more horsepower and increased stability during the tugs’ operation. Also, a modified staple placement is expected to increase steering forces by about 30 percent. To accommodate this increase, the tow point is being lowered and allowed to move further off center, increasing stability in working modes.

Increased brake tension on the bow winch will also accommodate the increased steering forces, according to Jensen, while tankage is divided in the new design to better control liquids on board, which could also improve stability and trim control.

“Horsepower is important for safety due to the increasing size, tonnage and draft of the ships calling on our ports now and in the future,” Kettenring explained. “Horsepower is needed to better control these ships to avoid accidents and environmental casualties.”

For this project, Jensen provided Crescent Towing all the structural assembly drawings and construction blueprints to aid the process of cutting and laying out steel pieces to minimize waste during construction.

The 70 metric ton bollard pull tugs will be built by Steiner Shipyard in Bayou La Batre, Alabama and are scheduled for delivery in November 2015 and January 2016.