This article follows on from Dispensing with cathodic protection – Part 1 which first appeared in Issue 273 of the Subsea Industries Newsletter.
In Dispensing with cathodic protection – Part 1 we discussed the problem of corrosion and the development of cathodic protection as an attempt to solve this problem. We made reference to a better solution which made sacrificial anodes or impressed current cathodic protection (ICCP) unnecessary in the prevention of corrosion on hulls. In this article we will explain this alternative solution and show practical examples of its use.
Entrance point to solving corrosion
The weakest link in corrosion protection is the coating. The entrance point to entirely preventing corrosion also lies in the coating. If the steel or other substrate is encapsulated and insulated from the corrosive effects of the sea and other destructive elements, corrosion will not occur.
But can this be achieved?
The Ecospeed difference
The Ecospeed family of coatings consist of a very thick layer of vinyl ester resin reinforced with a high concentration of overlapping special glass platelets of a large aspect ratio with added bonding agents to ensure perfect adhesion and complete insulation of the steel or other substrate from the corrosive elements such as seawater, barnacle glue and biofouling of any kind.
The surface to be protected must be properly prepared with a roughness profile of at least 75 microns and a cleanliness of SA 2.5. The coating needs to be correctly applied under the right conditions, but these are not particularly stringent. The application is standard with single feed airless spray equipment. It is essential that these simple requirements are met in order for the coatings to make the use of cathodic protection unnecessary. However, once the coating is correctly applied, it will last the life of the hull without the need for repainting, so the attention to detail in the application will more than pay off in lifecycle cost savings.
Case studies
SeaLaunch Odyssey
Over the 25 years that the Ecospeed coatings have been in broad use, there have been many instances where owner and operators have successfully abandoned the use of anodes and ICCP after correct application of these special glass-based coatings.
An interesting case is the SeaLaunch Odyssey, a semisubmersible that was converted for use as a sea-based rocket launch platform by Boeing and partners in their satellite programs. The vessel, along with a sister ship used as a command and control center, would sail from Long Beach, California to the Equator and launch a rocket with a satellite payload from there. When not on a launch mission, the Odyssey would lay up in port and the hull would foul considerably. The owners and superintendent were dissatisfied with the previous hull coating approach – conventional antifouling – and looked for a better solution. Despite the cathodic protection in use, the coating was in very poor condition and completely removed in many places threatening corrosion of the hull.
After some five years of this, the vessel was blasted to bare steel and recoated entirely with Ecolock. The comments from the manager of the ship, Jan Bakke, Senior Superintendent for Wilhelmsen, reflect his direct experience with the coating on the ship.
“The main reason we chose Ecolock for the hull was to avoid the penetration through the paint by the fouling and to protect the hull. I saw that it’s not penetrating. It looks good. There were some jack-up rigs ahead of us in drydock. I saw how much steel they had to change due to a poorly protected hull. What they do is just put a lot of anodes on and sit there and then they have to go into drydock and change a lot of steel, instead of putting Ecolock on the hull to begin with. One of them had been in drydock for six or seven months changing steel. That’s a lot of money. They can get rid of all their anodes and all the rest of it and put this coating on. That would be a big benefit.”
This was Jan Bakke’s conclusion after years of using Ecolock on the Odyssey’s hull.
Ecolock in lieu of anodes, ABS approval
Over the years, evidence that cathodic protection was not needed with Ecospeed coatings had accrued, but it was largely anecdotal – feedback from users of the coatings who had dispensed with anodes or who noted that the ICCP system was not needed. However, there was no formal recognition from external laboratories or classification societies.
In April 2025, a project engineered by McDermott chose Ecolock as the coating for two LNG tankers being converted to floating storage units (FSTs) to be stationed off the coast of Canada on the historical territory of a Canadian First Nation. One of the reasons for the choice of Ecolock, was the fact that the coating replaced traditional cathodic protection. The classification society involved, ABS, was asked to ratify this. ABS wrote a letter, signed by the ABS Chief Surveyor, Offshore, as follows:
April 11, 2025
Attention: Mr. Xxxxx Xxxxxx
This letter is in response to McDermott’s request for ABS approval on the Ecolock coating system to be applied to the hulls for ABS Classed vessels (VID’s xxxxxxx & xxxxxxx) in lieu of application of anodes.
As ABS Engineering has performed a detailed review of the coating product within Work Order xxxxxxx.
Please note our acceptance of the Ecolock is based on the following conditions:
1) The work is to be completed to the satisfaction of the attending ABS Surveyor and installed in accordance with the processes and methodologies of the coating manufacturer.
2) A plan for inspection, monitoring and repair of the coating, including location, frequency and extent of inspection, is to be included in the RBI schedule which will be reviewed and approved by ABS.
3) ABS will accept this cathodic protection methodology, provided the effectiveness of the coating is confirmed (inspected) at intervals determined within the RBI process (which shall be approved by ABS), or in accordance with the prescriptive requirements for coatings. Please refer to Chapter 4, Section 2 of the Floating Offshore Liquefied Gas Terminal Rules, and Section 6 for ABS Guide for Risk-based Inspection for Floating Offshore and Fixed Installations.
Since the basic composition of all the Ecospeed family of coatings is the same, this validation by ABS is quite significant and confirms the growing wealth of evidence which shows that these coatings do indeed make anodes and ICCP unnecessary for hulls and other parts of the underwater ship to which they have been correctly applied.
There have been many other instances of the Ecospeed family of coatings replacing anodes and ICCP in corrosion prevention.
Conclusion
Corrosion has been and is a huge problem for ships and marine structures.
One approach to curbing this corrosion has been through the use of sacrificial anodes and impressed current cathodic protection to compensate for the inadequate protection provided by conventional coatings.
Now marine coatings have been developed which protect the hull from corrosion without the need for the anodes or ICCP.
This marks the beginning of a whole new approach to corrosion protection which is much more effective, less expensive and entirely safe for the marine environment.
Key takeaways from both articles
- Corrosion is Public Enemy No. 1 for ships and maritime structures.
- Anodes and impressed current cathodic protection are the traditional means used to compensate for inadequate coating protection, and mitigate the harmful effects of corrosion.
- There is a type of coating, including Subsea Industries’ Ecospeed family of coatings which, if properly applied, replace the need for anodes and ICCP.
- There are many examples of successful protection using Ecospeed coatings without sacrificial anodes or ICCP.
- ABS recently ratified the use of Ecolock (an Ecospeed coating) in lieu of anodes for the protection of two offshore FSUs.
- Does this type of coating spell the end of corrosion at sea?
