Aluminium Boats – 30m Whale Watcher

Undoubtedly one of the most well know marine boat painters in Brisbane, Ultra Marine Coatings have again selected Altex Commercial Marine Coatings for the new 30m Whale Watcher being built by Aluminium Boats Australia Pty Ltd.

So why did Ultra Marine Coatings choose Altex Coatings?
We all know that salt water is one of the most aggressive forces of nature against marine coatings, and with this in mind; the team at Ultra Marine Coatings went for the system they knew would provide the protection of new aluminium in the severe salt laden environment. 

A  tenacious primer is required, not only to bond firmly to the aluminium, but also to suppress the onset of filiform corrosion. A corrosion that all aluminium boat owners have seen at some time, particularly near holes and fastenings on the boat and is characterised as a white powdery substance beneath the coating – both coloured and clear coatings.

With moisture being able to penetrate through the coatings through minuscule imperfections in the coating, corrosion will undoubtedly forming. This corrosion can take place as filiform or pitting corrosion. Filiform corrosion is bought about by water, contaminants such as salt water, being able to get beneath the coating and react with the aluminium. As the water is taken up by the growth of this contamination, much of the time salt crystals, the corrosion expands, paint coatings bubble up, blistering open, finally allowing more water to penetrate underneath the edge of coating to spread the whole process over a large area.

Coatings above water: Altra~Bond 3094, Altra~Prime 504, Altra~Build 520 and E~Line 239
To prevent the onset of filiform corrosion, Altra~Bond 3094 was selected. Altra~Bond 3094 is a two pack epoxy primer that will suppress the onset of filiform corrosion aluminium by chemically bonding to the surface of the aluminium. With tremendous cohesive strength, similar primers to Altra~Bond 3094 are also used within the aircraft industry where adhesion and lightweight are paramount; in the military they must be compliant to Milspec P-23377d.

After applying the Altra~Bond 3094 a sealer was then applied.
Altra~Prime 504 Buff, was chosen for two reasons; an effective rock hard sealer that would protect the Altra~Prime 504 from abrasion and also a coating that could be carried over to all surfaces below water, again saving time and money by adopting the KISS principal.

Due to the expert workmanship of Aluminium Boats Aust Pty Ltd ensuring the boat was almost fair at time of construction, assured the minimalist amount of fairing wit AYB 421 Epoxy Resin and Microballoons was used.  Reducing preparation time and overall weight of coatings applied to the vessel, providing application and paint savings to the owner and when the whale watcher is fully commissioned - fuel savings.

With all surfaces fully primed, and having sanded the spot faired areas smooth 4 coats of Altra~Build 520 were applied.
Each coat of the Altra~Build 520 was meticulously sanded with varying grades of sand paper, to a fine defect free surface.
And then only after all undercoated surfaces were inspected by Mr. John Chaplain – Ultra Marine Coatings, was the complete topside coated with a recoatable high gloss 2 pack polyurethane; E~Line 239.

Coatings below water: Altra~Prime 504, Altra~Build 540, Pettit Vivid Antifouling
Having sealed the topside it made sense to apply the same epoxy primer/ sealer to all surfaces below water (alas Altra~Bond 3094 is not suitable for immersion).  To combat corrosion in sea water a thick barrier protection of Altra~Build 540, was applied in 2 coats @ a total 300 microns dry film thickness.

Altra~Build 540 (original formulation was developed in the 1960's as an offset to coal tar epoxy) remains relatively unchanged and is still the workhorse for coating applications in immersed conditions. In addition to the outstanding barrier protection it has an excellent recoat window and permitting the adhesion of antifouling coatings direct; WITHOUT the need for adhesion/ barrier coating such as a vinyl or chlorinated rubber – once again providing cost savings to the owner.

Finalising the below water coating system, Pettit Vivid Antifouling; a robust antifouling that would handle the high speed nature of the vessel was selected.  The request for Pettit Vivid antifouling is growing at a great rate of knots and is proving to be effective with excellent results. It was with this in mind, which led Ultra Marine Coatings to apply the aluminium antifouling. Not only is Vivid recommended for aluminium hulls, it can be applied to GRP, timber and steel hulls. Outboards, stern legs and sail drives can also be coated safely with Vivid antifouling.

The 30 Whale Watcher Fast Ferry will be stationed at Manly, Sydney.