Re: Bottom paint everything?
Try to think of it like this... The engine in your car is grounded to the frame of your car. In your boat, that current wants to find the easiest way to get to a ground (water). The anodes conduct electricity better then a prop shaft or an outdrive so the current goes thru them, in to the anode, then in to the water. They are called sacrifical anodes because they will corrode as the current goes thru it to the ground rather then thru what ever it is protecting because the corrosion happens at the point of the discharge of the current.
Where many people go wrong is that they paint everything with bottom paint. Bottom paint has copper in it which is a good conductor. Let's say someone was to paint the bottom and the paint touches the outdrive and the trim tabs, they have just made a path for the current to go from the outdrive to the trim tab thru the copper in the paint and now the trim tab becomes a path for the current to go to ground and will begin to corrode.
As mentioned above, if you want to paint whatever is in the water, read the instructions on the paints that are available to see what is compatable with those items. And never, ever paint the anodes!