NTSB/MAB-18/19

National Transportation Safety Board

Marine Accident Brief

Capsizing and Sinking of Towing Vessel Gracie Claire

Accident no. DCA17FM025

Vessel name Gracie Claire

Accident type Capsizing

Location Tiger Pass, 1.3 miles southwest of Lower Mississippi River in Venice, Louisiana

29°15.06’ N, 089°21.49’ W 

Date August 23, 2017

Time 0756 central daylight time (coordinated universal time – 5 hours)

Injuries None

Property damage $565,000 est.

Environmental

damage

Narrow oil sheen, 1 mile long, observed; 1,100 gallons of diesel fuel discharged;

approximately 655 gallons recovered

Weather Cloudy, winds northwest at 3 mph, air temperature 80°F

Waterway 

information

Tiger Pass is an outlet to the Gulf of Mexico near mile marker 10 on the Lower 

Mississippi River. The channel is 14 feet deep and 150 feet wide.

On August 23, 2017, at 0756 local time, the towing vessel Gracie Claire was moored in 

Tiger Pass near mile marker 10 on the Lower Mississippi River in Venice, Louisiana.1 While taking 

on fuel and water, the towboat began to slowly list to starboard. After the wake of a passing 

crewboat washed onto the Gracie Claire’s stern, the list increased. In a short period of time, water 

entered an open door to the engine room and flooded the space. The towboat sank partially, its bow 

being held above the water by the lines connected to the dock. All three crewmembers escaped to 

the dock without injury. Approximately 1,100 gallons of diesel fuel were discharged into the 

waterway. Damage to the Gracie Claire was estimated at $565,000.

Gracie Claire moored for repair following sinking. (Courtesy of Triple S Marine)

 1 In this report, all miles are statute miles.
Capsizing and Sinking of Towing Vessel Gracie Claire

2 NTSB/MAB-18/19

Location where Gracie Claire sank in Tiger Pass while vessel was refueling at John W. Stone Oil 

Distributor dock in Venice, Louisiana. (Base map and satellite image from NOAA ENC® Viewer)

Accident Events

At 2135 on August 20, 2017, the Gracie Claire, a 45-foot-long towboat, departed Morgan 

City, Louisiana, pushing two empty hopper barges. On board were a captain, a mate, and a 

deckhand. The vessel arrived the next day in Venice, Louisiana, where the barges were dropped 

off. On the evening of August 22, the crewmembers began assembling another tow and then

moored at a nearby dock for the night. 

The next morning, on August 23, a new captain and deckhand came aboard the Gracie 

Claire. At 0720, before resuming assembly of the tow, the crewmembers got the vessel under way 

to load fuel and water. According to one crewmember’s statement and video evidence, the vessel’s

freeboard was only a few inches at the stern.

2

About 20 minutes later, the towboat arrived at the fuel dock of John W. Stone Oil 

Distributor (Stone Oil) in Tiger Pass, an outlet from the Lower Mississippi River to the Gulf of 

Mexico. The captain moored the towboat bow-in, perpendicular to the seawall (bulkhead), with 

two lines extending directly ahead from a centerline bitt at the bow to a single mooring bollard 

ashore. Soon afterward, at 0750, using the starboard-side fill pipes, the captain began loading the

fuel tank forward of the deckhouse while the deckhand filled the water tank aft of the deckhouse.

 2 Freeboard is the distance between the waterline and uppermost watertight deck.
Capsizing and Sinking of Towing Vessel Gracie Claire

3 NTSB/MAB-18/19

The deckhand, who had just begun 

working in the maritime industry a month prior,

told investigators that the towboat appeared to be 

sitting lower in the water before he began loading 

the water into the tank; however, he did not 

consider the condition unusual compared to the 

vessel’s draft during other fueling evolutions he 

had observed. The Gracie Claire began listing to 

starboard as fuel was loaded through the

starboard fill pipe at a rate of 140 to 150 gallons 

(972 to 1,041 pounds) per minute. The new load 

was in addition to the estimated 1,200 gallons 

(8,640 pounds) of fuel already in the tank. 

According to the captain, listing to one side 

during fuel-loading was not uncommon. He told

investigators that the Gracie Claire would often 

list to anglesthat submerged the deck edge. When 

the Gracie Claire listed to one side during 

refueling, his practice was to stop fueling and 

then resume filling the tank on the opposite side

to bring the towboat to an even keel because he 

believed that there were two separate fuel tanks,

one on the starboard side and one on the port side.

In fact, there was only one fuel tank with a swash

bulkhead on the centerline of the vessel that 

allowed fuel to flow from one side of the tank to 

the other.

As loading continued, video captured by 

the camera on the dock shows a disturbance on 

the surface of the water at the stern of the 

Gracie Claire. The water motion indicated a 

current acting on the starboard side.

The video footage showed that at 0755 an 

unidentified crewboat was traveling in the middle 

of the channel. When the crewboat passed the 

Gracie Claire, its wake washed onto the 

starboard side of the towboat’s stern. The 

towboat then slowly rolled to starboard as more 

of the starboard-side main deck became 

submerged. Within 90 seconds, water began 

flowing over the sill of the open engine room 

door on the starboard side. As the crew began 

evacuating to the dock, the Gracie Claire

continued to roll until it was almost completely 

submerged at 0802. The mooring lines held the 

bow above the water’s surface.

Screenshots of Gracie Claire, starting a 

minute after loading began through sinking, 

from video captured by southwest view of 

dock’s camera. (Video courtesy of 

John W. Stone Oil Distributor)
Capsizing and Sinking of Towing Vessel Gracie Claire

4 NTSB/MAB-18/19

While the vessel was sinking, the captain tried to close the fuel tank vents and fill pipes to 

prevent oil from discharging from the tanks, and the deckhand went into the deckhouse to awaken 

the relief captain and help him escape. All three crewmembers abandoned the towboat without 

injury.

The Gracie Claire was salvaged 2 days later. Due to the water damage, the owner 

refurbished or replaced machinery and equipment, including wiring, motors, electrical fixtures, 

and galley equipment. Additionally, the owner converted the rudder compartment into three 

separate compartments, each with access from the main deck, by installing two longitudinal 

watertight bulkheads.

Gracie Claire during salvage. (Courtesy of Central Maritime)

Additional Information

The Gracie Claire’s owner, Triple S Marine, began operating the vessel after purchasing it 

in 2006. The towing vessel was built in 1977 as a twin-propeller inland push boat with a steel hull 

and a three-level deckhouse. The exterior of the main deck was fitted with a 14-inch-high bulwark 

that included freeing ports to allow water to drain from the deck. Located on the starboard side of 

the main deck were two doors, one to the galley, forward, and one to the engine room, amidships. 

There was another engine room door on the port side. The bottom coaming of each door was 

elevated 20 inches above the deck. 

Beneath the main deck, four watertight bulkheads divided the hull into five compartments. 

In the fuel and water tanks, centerline swash bulkheads were installed to improve the towboat’s 

stability by preventing the quick shift of the weight of fuel and water from one side to the other

when the tanks were slack (not full). The first opening in these bulkheads was 24 inches above the 

bottom of the tank.
Capsizing and Sinking of Towing Vessel Gracie Claire

5 NTSB/MAB-18/19

The Gracie Claire was drydocked on August 1, three 

weeks prior to the accident. Employees from Triple S Marine 

inspected the underwater portion of the hull, and shipyard 

workers replaced the port shaft and propeller. No alterations 

or new equipment were added that would have increased the 

weight of the towboat and thereby changed its stability.

Following the accident, a damage assessment of the 

vessel during drydock revealed a 1-inch diameter hole in the 

bottom of the rudder compartment. The marine surveyor

performing the assessment told investigators that the hole was 

likely present before fuel was loaded onto the towboat.

Acompany representative stated that, among measures 

to ensure stability of the Gracie Claire, Triple S Marine’s

policy required the captain to check the rudder compartment 

for leaks each week and did not allow the vessel to be moored 

“bow first” (bow-in) if “excessive current was present.”

Investigators estimated the current’s speed at the time of the 

accident was 1 to 2 knots (1.1 to 2.3 mph).

The captain obtained his mariner’s license in 1983. He 

told investigators that he had served as a captain for Triple S 

Marine for over 5 years before the accident, had worked on 

the Gracie Claire often, and had fueled the company’s

towboats more than 100 times. The deckhand started working 

in the maritime industry and with Triple S Marine only 

4 weeks prior to the capsizing.

Analysis

Several factors affecting the stability of the 

Gracie Claire led to its capsizing. Before the vessel arrived at 

the Stone Oil dock to take on fuel, the rudder compartment 

likely had been flooding from the hole in the bottom of the hull, a water ingress that the crew was 

not aware of. The water level in the compartment would have risen until it equaled the water level 

outside the towboat, nearly filling the compartment and creating the equivalent of a slack tank.3

The lost buoyancy from the water in the compartment would have resulted in the towboat having 

less freeboard. A lower freeboard would have decreased the towboat’s stability, because the main 

deck edge would be submerged at lesser angles of heel.

4 The lower freeboard would also have 

made it easier for waves to wash across the main deck.

By mooring perpendicular to the seawall and not parallel to the waterway, the Gracie Claire

was subjected to a heeling moment caused by the river current. When the captain and deckhand 

 3 A slack tank, which is partially filled, generally causes a reduction in a vessel’s stability due to the motion of 

liquid in the tanks, an effect described as free surface. Free surface effect occurs because the liquids can shift to the 

low side of the tank as a vessel heels.

4 Generally, when a vessel’s freeboard deck edge submerges, the vessel’s maximum righting arm is reached. 

Righting arm is an indication of a vessel’s ability to counter capsizing moments at heel angles.

Plan view of Gracie Claire’s hull, 

not drawn to scale. (Based on 

postaccident sketch by marine 

surveyor)
Capsizing and Sinking of Towing Vessel Gracie Claire

6 NTSB/MAB-18/19

began loading fuel and water through the starboard fill pipes, the vessel already had a starboard 

list. Although the fuel and water tanks ran the full breadth of the hull, the centerline swash 

bulkheads would have contained the loaded liquids on the starboard side of the tanks until they 

reached the height of the 24-inch openings above the tank’s bottom. Because the liquids would 

have filled only the starboard side of their respective tanks, the vessel began listing further to 

starboard.

At the time, the equalizing line valves for the fuel oil tank were open, which was intended 

to balance the level of the tank’s contents on each side of the centerline swash bulkhead. Based on 

24 inches of fuel oil above the pipe, investigators calculated that the line would transfer 

approximately 70 gallons per minute. However, considering a fill rate of 140 to 150 gallons per 

minute and the vessel’s continued heel to starboard, the captain was filling the tank at a rate that 

exceeded the capacity of the equalizing line to level the tank.

Aware of the increasing starboard list during filling, the captain decided to shift fuel-filling 

to the port side of the tank to counter the starboard list. He believed that a reduction in the list

would occur because the fuel being loaded would accumulate on the port side, or high side, of the 

tank. However, with the vessel already listing to starboard, once the fuel reached the holes in the 

swash bulkhead on the port side of the fuel tank, the added fuel would shift by spilling over to the 

starboard side through the swash bulkhead openings, therefore exacerbating the starboard list. At 

the same time, the floodwater in the rudder compartment and in the water tank would also shift 

further to starboard. Had the water in the rudder compartment been discovered, the Gracie Claire’s 

owner or captain presumably would have taken measures to eliminate the water in the space before 

taking on fuel and water.

While the captain was filling the tank from the port side, the crewboat that passed astern

added to the heeling forces on the starboard side. First, the displaced water of the passing vessel

pushed the side of the hull below the waterline. Second, as the waves from the crewboat’s wake 

washed over the bulwark and onto the main deck of the towboat, they added weight on the 

starboard side of the main deck.

5 With the starboard deck edge submerged, the Gracie Claire

would have rolled more easily. Once the vessel reached a heel angle that allowed water to reach 

above the 20-inch coaming of the open door leading to the engine room, the vessel down-flooded

and rapidly sank.

Probable Cause

The National Transportation Safety Board determines that the probable cause of the 

capsizing and sinking of the Gracie Claire was the towing vessel’s decreased stability and 

freeboard due to undetected flooding through a hull leak in the rudder compartment, which made 

the vessel susceptible to the adverse effects of boarding water from the wake of a passing vessel.

 5 Water from boarding seas trapped on decks by bulwarks can significantly reduce a vessel’s stability due to 

several factors: (1) the additional weight of the water is added high on the vessel; (2) the freeboard is reduced due to 

the added weight; (3) the weight, which is added to the vessel’s low side, shifts the vessel’s center of gravity farther 

outboard.
Capsizing and Sinking of Towing Vessel Gracie Claire

7 NTSB/MAB-18/19

Vessel Particulars

Vessel Gracie Claire

Owner/operator Triple S Marine LLC

Port of registry Morgan City, Louisiana

Flag United States

Type Towing vessel

Year built 1977

Official number 584694

IMO number N/A

Classification society N/A

Construction Steel

Length 45.1 ft (13.7 m)

Draft 6.6 ft (2.0 m)

Beam/width 21 ft (6.4 m)

Gross registered tonnage 62

Engine power; manufacturer 900 hp (671 kW) (2) 12V71; Detroit Diesel

Persons on board 3

NTSB investigators worked closely with our counterparts from Coast Guard Sector New Orleans

throughout this investigation.

For more details about this accident, visit www.ntsb.gov and search for NTSB accident ID 

DCA17FM025.

Issued: August 13, 2018

The NTSB has authority to investigate and establish the probable cause of any major marine casualty or any marine 

casualty involving both public and nonpublic vessels under Title 49 United States Code, Section 1131(b)(1). This 

report is based on factual information either gathered by NTSB investigators or provided by the Coast Guard from its 

informal investigation of the accident.

The NTSB does not assign fault or blame for a marine casualty; rather, as specified by NTSB regulation, “[NTSB] 

investigations are fact-finding proceedings with no formal issues and no adverse parties . . . and are not conducted for the 

purpose of determining the rights or liabilities of any person.” Title 49 Code of Federal Regulations, Section 831.4.

Assignment of fault or legal liability is not relevant to the NTSB’s statutory mission to improve transportation safety 

by conducting investigations and issuing safety recommendations. In addition, statutory language prohibits the 

admission into evidence or use of any part of an NTSB report related to an accident in a civil action for damages 

resulting from a matter mentioned in the report. Title 49 United States Code, Section 1154(b).