Advice needed : Survey found electrolytic corrosion

[jorxster]

Hi all,

So I think I've found the right boat for me, she's a corten steel 1987 Feltz Skorpion built in Germany (I'm here in New Zealand).

I just had her surveyed on Monday. The surveyor, (a captain and engineer with many decades of experience) found some blisters and bubbling up around the zinc anodes. He's asked me to get an electrical engineer in to take a look as he thinks it may be electrolytic. My issue is, the original electrician the previous owner used is booked out to the end of the year, meanwhile the broker's sales agreement says I only have until monday to make my decision! Regardless of if I want a follow up survey.

So, this is a small excerpt from my survey report -- how serious is this, and at what difficulty to fix? This is a steel boat so any and all corrosion concerns me greatly. (I'd insert an image but seems this forum doesn't support it)

"The hull exhibited many blisters in the antifouling. When opened, shiny steel was found to be underneath.

"This has been an issue in the past, as around all the skin fittings, it was obvious that repairs had been undertaken at some stage.
The cause for this would appear to be electrolytic. It is advised that a marine electrician should check this to ensure that there are no issues attributed to the vessels systems.
The anodes all showed little wear apart from two hull anodes which had slight erosion. Noticed on the starboard hull were studs for extra anodes.
Too many anodes can be an issue as too little. This may be the reason for two missing.

Regardless, I am wondering, A. how to repair the blisters (re-haul out and anti-foul again?) but more importantly, B. how to stop them or get to the root cause? And how serious is it? He does go on to say the hull itself is in good shape. "Plating on the hull showed very little wastage."

Related : when looking at the boat I did see a "Victron Galvanic Isolator" installed.