Electrical System Upgrade Help

I have been restoring and fixing all of the gremlins in my 92 SNCB for the last few months. I am now working on the electrical system. My boat sounds like the other early 90's models with poor grounding in the dash and gauges along with what appears to be inadeuqate power supply wire from the battery/solenoid up to the ignition switch on the dash. I have just upgrade to the GT40 100 amp alternator and added a second Odyssey battery for the stereo system and that part is working great...it is just the gauges reading inaccurate and/or not supplying enough power needed such as dim dash lights/nav lights/perfet pa$$ flipping on and off with numerous accessories turned on.

I beleive my boat has a 20 amp igntion breaker/switch at the dash. Others have mentioned that the main power wire from the battery/solenoid up to the igntion switch is too small such as a 12 gauge wire. I want to run a new main power from the back up to the front in an 8 gauge size right the igniton breaker. I had planned to change the current 20 amp ignition switch over to a larger 30 amp igntion switch adding more capacity.   So here is my question...by running a new 8 gauge wire up to the igntion switch should I upgrade to the larger 30 amp switch or is the 20 amp sufficient in size? I am not an electrical engineer so I don't want to just change to a 30 amp igntion switch and cause a potential meltdown or burn up something. I will also be replacing all of the current blade connectors on the gauges and adding heat shrink along with adding a negative ground wire from each gauge to a ground distribution block to help.

Does all of this sound OK? Any potential problems or concerns? Thanks in advance!

rmcdonald is right about tracing grounding issues. However, its well known that the early 90's Nautiques in particular have inadequate power and ground wires coming to the dash. Running larger gauge wires should help (and certainly wont hurt anything).

Replacing the 20A ignition breaker with a 30A would allow your ignition circuit to draw more current before it trips- but thats not something you want to do. Just keep the 20A breaker and run a larger power and ground.