Pictures/Diagrams of your boats electrics

[ducky]

I'd classify essentials as motor and bilge pump and anything that you could really be in trouble if they stopped working.

Edited to fix typos

[chris srsc]

not sure if this helps at all....

DualBatteriesIsolator.jpg (39.17 KiB) Viewed 790 times

2015-2batt_1eng_2.png (48.27 KiB) Viewed 789 times

[cobby]

Things like sounders and led nav lights use 2/5ths of fa current. Any decent 80ah battery would be fine for a lot of setups or even a twin setup via isolater switch with smaller batteries. Things like electric motors I'd have a dedicated battery purely to simplify wiring up the front and reduce risk of draining all batteries.

Some beefy cabling from batteries to switch each fused. Same beefy cable fused again to a busbar tucked inconspicuously under the dash up high. Things like bilge pump, lights etc are fed via a switch panel, sounder and radio direct feed off the busbar. Negatives all terminated at the battery via a separate busbar. Engine electrics run direct from the isolater and terminate at the battery/s. A few cable ties and tape can make the install very very neat