I can't help with the specifics re the 58 but don't be surprised at breakers that look original but aren't. Do you have the original manuals/blueprints for your boat? If not, it is the best cost/benefit $75 (or thereabouts) that you will ever spend. It will contain all info and drawings for your boat and will quickly allow you to identify how things work and what was original. You can get them from Hatt if you supply them with the hull number. I'm sure someone will post the phone number and name of the lady that handles this - I can't recall!
I have three breakers that appear original but they are not; one labeled "fuel Transfer", one labled, "Rotary Generator," and one labeled "Rotary Transfer."
In our case, the first provided the ability to transfer fuel from what was originally the forward waste tank to the forward main fuel tank, giving the boat an additional 105 gal fuel capacity (up to 807). The second was the breaker for an inverter; the third was to transfer certain circuits from the "normal" AC path (shore power/genny) to the inverter. All were labeled exactly the same way as the oem breakers and you would never have known that they weren't oem from their appearance.
Perhaps a tank was converted on your 58 but if so, the only ones "available" are the waste tanks. I can't imagine any process that would I would trust to convert a waste tank to a water storage tank. Although the boat could have initially been put in service that way I suppose - with waste never being put in the tank. Also, I guess it's possible that a water tank was added somewhere. And, of course, the other possibility, since I don't know about the 58, is that the 58 DOES have an additional water tank that requres separate filling. But the oem info will show that either way.
Let us know!
