Salt Water Corrosion on Aluminum Surfaces

2017 March 17
by Chris Brown

A 1987 121’ Heesen Yacht, hauled at Lauderdale Marine Center, was showing the wear and tear you would expect on a 30 year vessel. The captain and engineer on this yacht contracted both High Seas Yacht Service and High Seas Hydraulics to perform a number of tasks on both the hydraulic systems and running gear.

As part of the running gear work, our High Seas Yacht Service team pulled the rudders for routine maintenance.

Salt water effects on aluminum

Upon removal of the rudders, we found significant corrosion in the rudder housing in the area of the packing glands. Prolonged exposure to salt water can cause corrosion of aluminum by creating aluminum oxide. The salt does not directly attack the aluminum, but causes an electrochemical attack like a catalyst that results in the corrosion. This is the white deposit that you find on aluminum. The reaction rate is usually fairly slow, but on this 30 year old vessel the salt water had definitely taken its toll.

Once the rudders were pulled, we inspected the rudder shafts and found them to be in excellent condition.  However, the repair of the aluminum would cause damage to the lower rudder bearing (bushing) so the vessel opted to have us remove them and fabricate new for installation.  Rudder bearings are machined in our machine shop – Straight Line Marine.  It is convenient to have a machine shop in the same facility, Lauderdale Marine Center, in order to dry fit the part and make repeated passed for a perfect fit. As part of the running gear work on this vessel, we also pulled and refurbished the props on the yacht.

With the proper care, maintenance and service even a 30 year old classic boat can return to the sea for many more years of cruising the world’s oceans.


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