My new to me '73 Islander 30 Mark II has a 20 amp shore plug that runs directly to a block. From there it is split into a couple of circuts with lights and plugs. It is grounded to the engine but no ground goes to the block and the 3 or 4 recepticals in the boat are all 2 prong 110 with no ground. There is no AC panel, fuses or breakers on the boat. I have not tried to power up the system and am reluctent to even try. I am planning on upgrading the AC to a 30 amp shore power plug. I think I will be putting in a panel with a main breaker and 3 or 4 circut breakers. I have read somewhere that I should be grounding to the engine and also to every one of my thru hulls. Is this neccesary? My plan was to run the ground to the engine and then to the panel. Also, I will be rewiring the existing circuts. Should I be running a 3 wire to each receptical/light and grounding them as well? I have been told that electrical grounding on a boat is different from a structure on shore. One last question is should I be replacing the DC panel at the same time. It seems to be OK.