23 April, 2017
Galvanic corrosion does not always occur below the waterline and can often be found on aluminium masts and booms that have stainless steel fittings attached to them.
In the example above a stainless steel kicker slider has been riveted to the boom but the insulation between the dissimilar metals has failed or was never there in the first place. This becomes far worse in a humid, salty environment and the damage can often be underneath the component where you can’t see the extent of the damage.
When galvanic corrosion occurs the aluminium becomes powdery and crumbles in the hand. This makes the material weak and under load the area can fail resulting in the components pulling out from the mast.
To prevent or at least reduce this the metals should be insulated from each other with an insulating compound or the component can be lacquered before being mounted. This includes the monel rivets going through the aluminium.
Always check your mast fittings for signs of corrosion and if in any doubt get a rigger to remove the components to check the condition of the aluminium underneath