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Nov 26, 2023

What can I use to lubricate metal?

Colin Staples has a stiffened outboard bracket made of aluminium and stainless

Colin Staples has a stiffened outboard bracket made of aluminium and stainless steel. What is the best way to lubricate the fitting?

Outboard brackets can be made of different metals, so what is the best way to keep the fitting lubricated?

We keep our Hunter Duette on a mooring in the Hamble River where fouling is bad.

The prop of the 5hp Honda outboard in the well quickly fouled.

All efforts with antifouling and proprietary prop cleaners failed so we resorted to lifting the outboard out each time and storing it in the cabin.

At over 80 this became too much of a task, so I invested in an outboard bracket for the transom able to take up to a 10hp motor; I assumed it would be more than up to the task.

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It's constructed mainly of aluminium and stainless steel.

All went well at first but gradually the lifting and tilting mechanism stiffened up and it's now almost impossible to tilt and lift despite grease, WD40 and copper spray lubricants.

I have to use a screwdriver to operate the release levers.

Do you have ideas on the best way to lubricate the metal to keep it moving freely?

I wonder if perhaps stainless steel, aluminium and copper are not good bedfellows.

Colin Staples

Vyv Cox replies:

There is a galvanic reaction between copper and aluminium but the combination of aluminium and stainless steel can also be problematic.

I’d certainly avoid the copper spray as it's not going to help at all. If the bolts can be withdrawn I’d run a tap down the thread to ensure that the aluminium of the release levers is clean and free of corrosion product.

Silicone grease is the best bet for lubricating differing metals

Otherwise it's a matter of running the threads up and down many times, maybe try a mild abrasive such as T-cut or Brasso to lightly wear away the aluminium.

Try to wash this out with a solvent afterwards, perhaps turpentine or paraffin.

Probably the best lubricant to use then is a silicone grease, which will help to exclude any water.

A silicone aerosol spray can help too.

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