I have not heard of any news to upgrading the electrical system, did you increase the alt size or at least use a battery isolator and 2 batteries?
I am also wondering did you use all marine grade/rated wiring and connectors?
As only tinned wire is required for use as well as uscg approved electrical.
The reason I mention is because this is something I do for a living is marine electrical and systems, as well as mechanical as well. If you do not use marine wire and connections then no matter wha spray you use on them they will rot out over time.
Being 1200w of system does not really effect the charging system what does is the current/amp draw from everything on it if the system was mply ooked up to he main or a second battery you may find that it kills your batteries or the charging system.
Also marine audio is not water proof as they state, make sure to keep the amps out of direct moisture or they will fry, also seal very well around and any holes above the radio as they as well are not water proof only the face plate is and even then not as much as we would think, just a little water into the back holes on top of the radio will fry it, I repair/replace a lot of radios due to water entering them, I also replace wiring and connections and fuse/ground blocks all the time on boats because automotive stuff was used, a standard car audio power wire lets say that is only $8 per foot will cost one lets say $18 per foot, there is a reason for this and the customers that I get usually do not blink at the price, a 1200w system of goot quality would run a customer near what you paid but in just wiring alone could be $800 easy!
When I say that car audio/wiring is used in boats I do not mean most customers did that themselves, instead places like mad marks, underground audio and other big name audio shops around town all have used non marine rated wiring here and I always end up repairing it the correct way. If done right the first time even though it seems very expensive it will save you down the road in costs.
One of the last ones I worked on, the major audio shop used a car electronics ground block, a car fuse block, car wiring, car power and ground cables, as well they zip tied the sirius radio to the radio harness so every wave or bump in the road was pulling on the harness on the radio then they did not seal around the face plate so water was seeping downward into the holes on the rear of the radio, they also used cheap marine speakers so everything lasted the customer only 11 months before problems, on wet days the radio may or may not work or only certain speakers a wave would cause problems as well, the speakers you could push your finger through, I had to replace everything except for one amp, cost the customer just over $2000 to have the repairs done even the speaker wires where car audio and not marine.
