Sealing Anode Thru Hull Studs

[Ti' Punch]

Fellow forum members, I come to you with hat in hand humbly requesting advice on properly sealing around the thru hull studs for my zinc anodes. When we bought the boat several years ago the studs had some kind of waxy putty smeared around them on the inside and outside of the hull penetration, including over the nuts and washers.

That putty seemed to be getting dried out and flaky, so three years ago during the annual haul out I had the yard pull the studs and reseal them. It looked like they used 4200 or some other similar sealant in the hole around the studs and then threaded the nut and washer down on top of the sealant. There was just a small amount of sealant squishing out from around the washers. This looked much cleaner than the old wax putty and seemed to work well at the time.

Last year we did a short haul to pressure wash the hull and change zincs. After the haul out I had a slow leak around one of the zinc studs. We just lived with it through the season and boat has been on the hard since last Fall. Now I'm getting her ready to go back in the water and need to address this. The sealant looked better but only lasted a couple years. I'm not even sure what the wax stuff was, but it was probably 10 years old at least when I replaced it and had never let a drop of water pass. What is the proper way to seal these things and why don't I just epoxy them in place so I don't have to worry about it any more? I assume they don't do that because it would make it a bear to get them out, but these studs seem pretty durable. Not sure they would need to be replaced again in my lifetime. What say ye all?

[coopec43]

I used Sikaflex 291 on mine but as I have yet to launch my yacht I'm not sure that is the answer. I definitely would not used epoxy though.

Many people seem to swear by butyl tape. I wonder if that would be appropriate?

[Searles]

Clean out holes ,totally clean of all old sealant re fit with thickened epoxy try to use high grade monel k500 or g2 bronze nuts and washers of parent metal ,job done fore ever .⚓️⛵️

[coopec43]

Maybe this is relevant?

https://www.sailnet.com/threads/ligh...tection.20142/


http://marinelightning.com/Informati...ndingGuide.htm

[coopec43]

I have four SS strips attached to the hull by countersunk bolts (sunk into the strips) I used Sikaflex 291 around the edges of the SS strips and under the CSK heads. Hope it works!