Hull Surface Treatment - HST - Case Study

Australia | South Pacific

Case Studies

HMAS Choules

HMAS Choules Ship

The ship had been in water for 21 months with weed growth acculmulating over that time to between 10mm and 20mm on the vertical sides. HST was applied to both sides of the ship over two consecutive days. There were no interruptions to the ships operation. HST requires no services from the ship and is fully self sufficient. The photos show the side of the ship before application and the results of HST six months after the application when the ship was dry docked.

HMAS Choules Before HST

HMAS Choules Before HST

HMAS Choules After HST

HMAS Choules After HST (6 Months)


MV Torrens

MV Torrens Ship

The MV TORRENS was treated with HST 4 1/2 months prior to dry-docking. Before the treatment the hull had 100% coverage of 30mm weed and algae on the lateral areas thinning to 10mm at the bilge keel. The photos show a comparison of the hull before HST and then after HST when the ship was dry-docked in Singapore. Between the treatment and dry docking new re-growth can be seen starting along the top section near the water line. HST is designed to keep the hull as close as possible to dry docking condition without the aggressive action of scrubbing or water blasting and the associated damage to the anti fouling paint plus environment. Treatment and re-growth frequency varies depending on the ships underwater coating condition, its operations and geographical areas of operation.

MV Torrens Before HST

MV Torrens Before HST

MV Torrens After HST

MV Torrens After HST (4.5 Months)


China Navigation

China Navigation Ship

HST was applied to the five ships - KOKOPO CHIEF, CORAL CHIEF, HIGHLAND CHIEF, PAPUAN CHIEF and ISLAND CHIEF. All the vessels were heavily fouled and the anti fouling paint on each was in very poor condition. This was due to the scrubbing action of brush carts used previously to clean the hulls of growth. The unfortunate result of this is the removal in large quantities of the expensive anti fouling paint along with increased growth. Each time a vessel is scrubbed using the old abrasive methods the paint becomes less and less effective in expediting the re-fouling of the hulls. The photos show typical sections of the hulls taken after a period of between 10 and 12 weeks since the new HST application.

China Navigation Before HST

China Navigation Before HST

China Navigation After HST

China Navigation After HST (3 Months)


Iron Monarch

Iron Monarch Ship

Ship had been in water for 21 months with accumulated growth of between 10mm and 15mm on the vertical sides. HST treatment was applied to just two 15 meter strips along the port side of the ship. The port side experiences greater growth as the Iron Monarch always berths starboard side thus exposing the port side to greater sunlight. The first application started 4 meters forward of the plimsoll markings and ran aft for approximately 15 meters. The second application started immediately aft of the ballast discharge and also ran aft for approximately 15 meters. The photos were taken by commercial divers 41 days later to compare between the treated strips and the remaining untreated sections of the ship. Full treatment of the ship was performed thereafter.

"Doing real good speed - she is galloping along... it was worth while doing and job well done - Thank You.”

Chief Engineer - Iron Monarch (After Full HST Treatment)
Iron Monarch Before HST

Iron Monarch Comparison Test (6 Weeks)

Iron Monarch After HST

Iron Monarch Comparison Test (6 Weeks)


Rhapsody Of The Seas

Rhapsody Of The Seas Ship

HST treatment to both sides of the hull after the ship had been in water for 48 months and last scrubbed in July 2010. Weed growth had accumulated in that time to between 10mm and 20mm on the vertical sides. HST was applied to the port side of the ship first and then the Starboard side 1 month later. The photos are of the port side and taken by commercial divers 21 days after the application to the port side.

"We have made better speed throughout the Pacific crossing than anticipated”

Captain - Rhapsody of the Seas (After HST Treatment)
Rhapsody Of The Seas Before HST

Rhapsody Of The Seas Before HST

Rhapsody Of The Seas After HST

Rhapsody Of The Seas After HST (3 Weeks)