Here is my rationale:
When I bought my boat, the thru hulls were bonded by the original owner. He owned the boat nearly 40 years and did everything right. It's become my rule of thumb on this ongoing project to just copy what the old guy did and I'll be fine. So, last year, a different guy who brokered the sale to me told me that bonding will not be necessary once we replaced the thru hulls (Groco). I went with that, and now 18 months later, I see that there is some green on a couple of the thru hulls. This tells me there is corrosion, so I bonded them yesterday. I will watch closely to see if anything changes. The question is, if they are correctly protected, then how long would it be before I begin to see the signs of corrosion? Also, since I am basically getting the boat ready for the next owner, I have to think in terms of what the surveyor will report. Maybe I should run this by a local who knows (Los Angeles).
1968 Cal 2-30