AQUENAL PTY LTD 

Aquatic Environmental Analysts 

Marine, Estuarine and 

Coastal Assessment ABN 86 081 689 910 

244 Summerleas Road Tel: +61 (0)3 6229 2334 

Kingston, Tasmania Fax: +61 (0)3 6229 2335 

AUSTRALIA 7050 www.aquenal.com.au

Keith Johnson 

Managing director 

Commercial Diving Services Pty Ltd 

PO Box 126 

Dapto, New South Wales, 2530 

 

27th February 2009 

To whom it may concern, 

Mr Keith Johnson of Commercial Diving Services Pty Ltd has requested my expert opinion 

surrounding whether his novel Hull Surface Treatment (HST) Technology poses a biosecurity and/or 

water quality risk through the introduction of biofouling pests and/or toxic biocides into the 

surrounding marine environment. 

What qualifies me to provide this advice? 

I have been researching the biosecurity risks associated with vessel biofouling for over 10 years. I 

began my interest in this area in 1996 by undertaking a Masters Degree in Applied Science with the 

Australian Maritime College, Tasmania where I investigated the biosecurity risks associated with 

biofouling on merchant vessels visiting northern Tasmania. In 1999, I joined Cawthron Institute in 

New Zealand as a Marine Biosecurity Scientist where I provided underpinning research for the 

development of policies and procedures for managing marine biofouling pests. Then in 2006 I joined 

the Australian Quarantine and Inspection Service as a Marine Pest Advisor to assist with the 

development of Australia’s proposed Biofouling Management Requirements, including raising 

awareness of the issue through the International Maritime Organisation. It was during my pursuits 

for new environmentally-friendly technologies for mitigating the translocation of biofouling pests 

that I was first exposed to Mr Johnson’s HST Technology during his visit to Canberra on 16 April 

2008. I now work for Aquenal Pty Ltd in Hobart where I am responsible for managing marine pest 

related research and consultancy projects. 

Biosecurity risk - biofouling pests 

Removing and releasing biofouling into the marine environment through hull cleaning may facilitate 

the introduction of invasive marine pests. Hence, the Australian and New Zealand Environment and 

Conservation Council introduced a Code of Practice for antifouling and in-water hull cleaning and 

maintenance to discourage the practice (ANZECC 1997). However, these concerns largely surround 

the use of traditional rotational brush cleaning systems that are capable of removing high levels of 

biofouling (animal growth). Such high levels of biofouling are considered more likely to contain 

invasive biofouling pests, particularly in anomaly areas of vessels (e.g. bow thruster tunnels, 
AQUENAL PTY LTD 

Aquatic Environmental Analysts 

Marine, Estuarine and 

Coastal Assessment ABN 86 081 689 910 

244 Summerleas Road Tel: +61 (0)3 6229 2334 

Kingston, Tasmania Fax: +61 (0)3 6229 2335 

AUSTRALIA 7050 www.aquenal.com.au

underneath bilge keels, inside sea chests, and around rope guards, propellers and rudders) (Coutts 

1999, Coutts and Taylor 2004; Coutts and Dodgshun 2007). 

From my understanding, the HST uses thermal shock designed to treat only low levels of biofouling 

such as copper resistant algae that predominantly occur on the mainstream areas (i.e. flat-sides from 

the waterline to the turn of the bilge) of hulls that are responsible for causing significant 

hydrodynamic drag on vessels underway. While some vegetative stages of invasive marine algae can 

occur in these areas, they pose a low biosecurity risk relative to high levels of biofouling. However, 

the HST technology is capable of killing vegetative stages given the technology was originally based 

on treating juvenile stages of invasive marine alga (Wotten et al. 2004). More importantly, the HST 

does not clean or remove biofouling like rotational brush systems, but rather relies on thermal shock 

to kill the biofouling that remain attached to the hull until the vessel is underway. Therefore, in my 

opinion the HST is unlikely to pose a biosecurity risk because it: 1) treats low levels of biofouling 

that pose a relatively low biosecurity risk; 2) is capable of killing vegetative stage of invasive marine 

algae if present; and 3) sterilizes the hull surface without releasing defouled organisms into the 

surrounding environment. 

Water quality – release of toxic biocides 

Prior to the implementation of the ANZECC Code of Practice in 1997, it was common practice to 

remove unwanted biofouling while in situ using brushes. One study for example, demonstrated that 

approximately 95% of the total mass of copper biocides emitted into the marine environment over a 

four week period originated from the passive leaching, while only 5% originated from in-water hull 

cleaning (Schiff et al. 2004). However, in-water cleaning of antifouling coatings is known to 

significantly increase the release rate of toxic biocides beyond their normal leaching rates (e.g. 

Valkirs et al. 2003; Warnken et al. 2004). Conversely, the HST is unlikely to exacerbate the 

immediate release of biocides upon treatment because it does not clean, but sterilizes the hull 

surface. Furthermore, it is unlikely the biocides are able to be released from the treated surface until 

the dead algae is removed when the vessel is underway. 

Overall, I sincerely believe the HST is a much needed environmentally-friendly solution for reducing 

the hydrodynamic drag on vessel hulls and greenhouse gas emissions, thus supporting Australia’s 

commitments to the Kyoto Protocol. 

Regards 

Ashley Coutts - Senior Research Scientist - Marine Pests 
AQUENAL PTY LTD 

Aquatic Environmental Analysts 

Marine, Estuarine and 

Coastal Assessment ABN 86 081 689 910 

244 Summerleas Road Tel: +61 (0)3 6229 2334 

Kingston, Tasmania Fax: +61 (0)3 6229 2335 

AUSTRALIA 7050 www.aquenal.com.au

References 

Australian and New Zealand Environment Conservation Council (ANZECC), 1997. Code of practice 

for antifouling and in-water hull cleaning and maintenance. 12 p. 

Coutts, A. D. M., 1999. Hull fouling as a modern vector for marine biological invasions: 

investigation of merchant vessels visiting northern Tasmania. Unpublished MSc. thesis, 

Australian Maritime College, Launceston, Australia. 283 pp. 

Coutts, A. D. M., Taylor, M. D., 2004. A preliminary investigation of biosecurity risks associated 

with biofouling on merchant vessels in New Zealand. New Zealand Journal of Marine and 

Freshwater, 38: 215-229. 

Coutts, A. D. M, Dodgshun, T. J., 2007. The nature and extent of fouling in vessel sea-chests: a 

protected mechanism for marine bioinvasions. Marine Pollution Bulletin, 54: 876-886. 

Schiff, K., Diehl, D., Valkris, A., 2004. Copper emissions from antifouling paint on recreational 

vessels. Marine Pollution Bulletin, 49: 833-843. 

Valkirs, A.O., Seligman, P.F., Haslbeck, E., Caso, J.S., 2003. Measurement of copper release rates 

from antifouling paint under laboratory and in-situ conditions: implications for loading 

estimation to marine water bodies. Marine Pollution Bulletin, 46: 763–779. 

Warnken, J., Dunn, R. J. K., Teasdale, P. R., 2004. Investigation of recreational boats as a source of 

copper at anchorage sites using time-integrated diffusive gradients in thin film and sediment 

measurements. Marine Pollution Bulletin, 48: 371-377. 

Wotton, D. M., O’Brien, C., Stuart, M. D., Fergus, D. J., 2004. Eradication success down under: heat 

treatment of a sunken trawler to kill the invasive seaweed Undaria pinnatifida. Marine Pollution 

Bulletin 49: 844–849. 
 Ecowise Environmental (Victoria) Pty Ltd ABN 94 105 060 320 

Effect of HST Treatment on surrounding harbour water

Brett Thompson 

Ecowise NSW Laboratory Supervisor 

Abstract

Ecowise Port Kembla supplied a sampling and analytical service to Commercial Diving 

Services (CDS) as an independent laboratory in relation to HST hull treatment procedures. 

The Port Kembla laboratory analysed samples taken by CDS and an Ecowise sampler in order 

to compare baseline concentrations of several stress indicators in Sydney Harbour with the 

concentrations found in water post HST treatment. It was found that the analysis was 

comparable and application of the HST treatment procedure did not have any observable 

affects on surrounding harbour water. 

Introduction

A sampling and analysis scheme was undertaken to identify any changes to the surrounding 

harbour water as a direct result of HST treatment. The main environmental concerns 

identified by CDS and Ecowise were thermal shock; an increase in total suspended solids 

(TSS); eutrophication (excess nutrients e.g. nitrogen and phosphorus); and the leaching of 

biocides from the exterior antifouling paint of the hull. 

The active biocide ingredients contained in the antifouling paint of the ship involved in the 

sampling scheme were cuprous oxide and zinc pyrithione. Copper (Cu) and zinc (Zn) were 

analysed in pre treatment and during treatment samples as representatives of the presence of 

the active ingredients. A significant increase in either metal would indicate leaching of the 

respective biocides. 

Sampling location 

Sampling location was kept consistent by sampling pre HST treatment harbour water and all 

HST treatments during sampling on the hull directly beneath lifeboat number 5 on the 

starboard deck of the “Pacific Dawn” at Darling Harbour in the Port of Sydney. 

An Ecowise sampler accompanied the CDS team onto the harbour to collect independent 

samples. Samples were taken before HST treatment in order to establish a set of analysis 

representative of the surrounding harbour water. Duplicate samples were taken at the hull of 

the ship and approximately 30 meters perpendicular from the treatment site towards the 

middle of Darling Harbour. 

Using an YSI multi-probe, temperature and pH were also recorded for the two sites, as well as 

at distances of approximately 20 meters, 15 meters, 10 meters and 5 meters from the hull. 

Water directly influenced by the HST treatment was sampled by collecting duplicate samples 

of water directly above the device during operation. Although the path of the water would be 

influenced by harbour currents and harbour traffic, it was assumed that taking samples as 

close as possible to the device would give a worst case scenario for the affect of the treatment 

on surrounding harbour water. 

73 Military Road Port Kembla NSW 2505 Australia 

Telephone +61 2 4274 0433 Facsimile +61 2 4274 0434 Email wollongong@ecowise.com.au 

Brisbane ▪ Canberra ▪ Melbourne ▪ Sydney ▪ Regional offices
 Ecowise Environmental (Victoria) Pty Ltd ABN 94 105 060 320 

Results and Discussion

Table 1 Analysis of Cu, Zn, TSS, TN and TP in harbour water before and during HST 

treatment. 

The results in table 1 show that concentrations of Cu, Zn, TSS, TN and TP were comparable 

for both the surrounding harbour water and the water sampled during HST treatment. 

Table 2 Analysis of Temperature and pH in harbour water before and during HST 

treatment. 

The results in table 2 show that temperatures and pH values were comparable between the 

surrounding harbour water and the water sampled during HST treatment. 

Conclusion 

This study was conducted by Ecowise to independently investigate the affects of HST 

treatment on chemical and physical properties of harbour water. Environmental issues such 

as thermal shock; an increase in total suspended solids (TSS); eutrophication; and the 

leaching of herbicides from the exterior paint of the hull were of main concern. 

The results of field and laboratory analysis showed that concentrations and levels of the tested 

parameters in harbour water directly adjacent to HST treatment were not outside 

concentrations and levels of parameters expected in Darling Harbour water, within the Port of 

Sydney. Therefore no adverse effects of HST were identified by this study. 

Brett Thompson 

Chemistry Team Leader 

Sample site Cu (mg/L) Zn (mg/L) TSS 

(mg/L) 

TN (mg/L) TP (mg/L)

Blank @ Hull 1 <0.01 <0.01 8 0.4 0.05 

Blank @ Hull 2 <0.01 0.01 16 0.3 0.06 

Blank @ 30m 1 <0.01 <0.01 31 0.2 0.05 

Blank @ 30m 2 <0.01 <0.01 15 0.3 0.07 

Process Water 1 <0.01 0.01 13 0.3 0.06 

Process Water 2 <0.01 <0.01 15 0.3 0.07 

Sample site Temperature (°C) pH 

Baseline @ 0.5m 23.4 7.7 

Baseline @ 5m 23.1 7.9 

Baseline @ 10m 23.1 7.9 

Baseline @ 15m 23.2 7.9 

Baseline @ 20m 23.1 7.9 

Baseline @ 30m 23.2 7.9 

Process water 1 23.5 7.9 

Process water 2 23.4 7.9