Paint it, and bond it to the common bond ground. It's still going to get covered with marine growth anyway but at least you will have slowed the barnacles down a little.
Sail268, there is a product called propspeed, made for what you are doing. It is very expensive but also very effective. Info about it is here: http://www.propspeedusa.com/faqs.htm
If you do elect to use it, instruct the divers who clean your bottom to never use anything more abrasive than a diaper to wipe of any growth that may accumulate (there won't be much)
I applied this 8 months ago to the monster running gear on the big motor yacht I work on and the diver who cleans the bottom only ever wipes off a bit of slime once in a while.
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