I replaced my engine zincs April 2013. I normally check them once per year. I left it a bit this time and examined them today.
I checked the upper one and it was around 80% intact so returned it without replacing it. The lower one was a different story. On visual inspection it was 10% intact. However, I applied the squeeze test and the 10% simply disintegrated between my thumb and forefinger. It was replaced. I even was able to scoop out the soft zinc from the nut's screw hole. I cleaned the nut and used my BoatZinc.com zinc to screw in a new zinc ready for next year.
Here are the two zincs after 16 months.
Here's the BoatZinc.com info
Here's a look at the zinc I purchased from BoatZinc.com. They simply screw in to the brass nut.
I checked the upper one and it was around 80% intact so returned it without replacing it. The lower one was a different story. On visual inspection it was 10% intact. However, I applied the squeeze test and the 10% simply disintegrated between my thumb and forefinger. It was replaced. I even was able to scoop out the soft zinc from the nut's screw hole. I cleaned the nut and used my BoatZinc.com zinc to screw in a new zinc ready for next year.
Here are the two zincs after 16 months.
Here's the BoatZinc.com info
Here's a look at the zinc I purchased from BoatZinc.com. They simply screw in to the brass nut.