Bisso builds unique ASD tractor fleet on the Mississippi

Bisso Towboat Co Inc has become a major provider of marine and inland waterways services along the Lower Mississippi River, with a fleet of tractor tugs with azimuth stern drive (ASD) propulsion.

The Luling, Louisiana-headquartered company has 134 years of operations on the vessel highway through the US southern state, assisting ships between the mouth of the Mississippi River, southwest pass and Baton Rouge.

It specialises in assisting and docking vessels with a dedicated fleet of 11 tugboats, 10 of them ASD tractor tugs. Bisso operates the largest fleet of eco-friendly ASD tractor tugs on the Mississippi.

“We have evolved into building the only ship-assist fleet whose daily operating fleet is 100% ASD tractor tugs,” Bisso Towboat president, Scott Slatten, tells Riviera.

“We took delivery of six ASD tractor tugs built between 2015 and 2024.” This makes it the youngest of these fleets operating on the Mississippi, with an average age of 12 years.

Since 1890, Bisso has committed to delivering equipment and services for ships navigating and docking at the terminals of the Lower Mississippi and has ordered newbuilds with lower emissions than most towboats and tugboats on the river. 

Half of the newbuilds have exhaust gas aftertreatment equipment, including selective catalytic reduction (SCR) units to minimise NOx emissions and to comply with US Environmental Protection Agency (EPA) Tier 4 standards.

“Our three latest newbuilds are all Tier 4 compliant, greatly reducing our emissions,” says Mr Slatten. “We also sold and disposed of our oldest, less environmentally friendly tugs as we accepted delivery of these cleaner-burning tugs.”

The latest delivery was Mr Brian, which was christened at the Audubon Aquarium of the Americas at Woldenberg Riverfront Park in December 2024, completing the current newbuilding campaign. Although no newbuild orders are planned for 2025, another shipyard contract is expected to follow next year. “No newbuilds are presently under construction but the plan is to start another in 2026,” says Mr Slatten.

Mr Brian was named after Brian Cyprowski, who is Bisso Towboat’s vice president of operations and a member of the company’s executive team, with 37 years of experience with the US company.

“Mr Cyprowski and I have been through the wars together and he has stood by this company throughout. I probably should have named a boat for him a long time ago,” says Mr Slatten.

This 31-m tugboat was built by Main Iron Works in Houma, Louisiana as the sixth ASD tractor tug built by the shipyard in the past nine years for the owner.

It has a beam of 12 m, a hull depth of 4 m and a bollard pull of 68 tonnes. This comes from propulsion consisting of two Caterpillar 3516E main diesel engines generating 1,865 kW each at 1,600 rpm, compliant with US EPA Tier 4 emissions standards, and two Kongsberg US205S Z-drives, each with 2,400-mm four-blade stainless steel propellers in stainless steel nozzles.

Other features include US Coast Guard-approved engineroom monitoring and fire/smoke alarm systems, a fixed CO2 fire extinguishing system, Simrad navigation and wheelhouse electronics, soundproof insulation throughout the engineroom and crew quarters, stainless steel bitts and a bow staple.

Tanks on Mr Brian can store 137,100 litres of diesel, 50,000 litres of potable water, 8,300 litres each of lube and hydraulic oil and 9,100 litres of diesel exhaust fluid. Electrical service is provided by two 118-kW Caterpillar generators powered by two Caterpillar C4.4 engines.

This tug is equipped with a JonRie Series 240 escort winch featuring 152 m of 2¾-inch diameter Saturn 12 line and it has accommodation for four crew members.