I'm 67 and been around wood boats and ships a long time. I was a shipwright, etc. You bond metals together so they don't react with each other when in the water. Usually each metal object has it's own zinc. The only times I found wood damage around a fitting from electrolysis
was from improper wiring
giving off higher current. Usually some radio
wired backwards that passed current thru even when turned off. Enough so it would drain a battery
bank in a few days if not on a charger
. I saw a 36" prop that wasted it's blades in a month.
Your pictures look to me like a paint bond failure. It didn't stick well to the old paint and left areas for colonization. Once there is no paint, marine
organisms are entering the wood. The paint appears to be thick and probably for many years the bottom was just washed between coats of bottom paint
. It probably needed a good sanding
. On commercial
wood boats, we sanded between coats and usually stripped to bare wood about every 10 years. And before the EPA we had better paint and wood preservatives.
You're looking at a 40 year old boat. It's going to have some rot
, somewhere. The only perfect 40 year old wood boats just went thru a major rebuild
and haven't hit the water yet. Rot
organisms travels thru wood and can contaminate other woods they touch. There are products, I don't use, that can be poured or injected into soft wood to make it hard again. They don't restore the strength. You deal with it by cutting out the rot and replacing the wood.
Should you buy this boat, the old way of extending the life of wood boats was to keep rock salt
loose in the bilges. I still do. Salt
is a preservative. Also, boats and ship built before 1930 usually had salt boxes built into the sides, between the ribs, right under the deck
. On a properly curved deck
, water that collected under the deck or dripped thru the deck ran to the sides and thru the salt box and down the sides preserving the ribs, planks and bilge
. Don't dry out the hull.
My boat will be 73 years old soon. It had poor care for 20 years before I bought it, but had a copper sheathed bottom, and lived in salt water
. The hull is in excellent shape. There's one sister rib
and almost all the original planking. Topside is another story.