Help!! Blisters on keel

[Montanan]

Better to have blisters on your keel than blisters on your heel. Just saying.

[Franziska]

Originally Posted by SeaRags

Ok, I was wrong, there is no fiberglass, I scraped down a little further to the lead. Looks like the lead was painted, then an epoxy coating, then some kind of paint, then my ablative coat. Would it be bad to just sand it lightly to take off the blisters, then apply gel coat? Or just go straight to the ablative paint again? I just don't want to make a mess of things.

Looks like someone did paint the lead directly with copper antifouling.
Not a clever thing to do, as the two metals will corrode in seawater.

In a failed repair someone put a barrier coat on top to prevent that, but did not remove the old copper paint completely, but rather sealed it in. Result, the corrosion continued underneath.

Then they added more antifouling, which pops now.

If you have a lead keel, never put copper antifouling directly onto it, but apply few layers of epoxy first (sticks much better than gelcoat, which is unsuitable, to the lead if you sanded the lead properly before).

Suitable epoxies for this are for example Interprotect or VC Tar Epoxy.

Go sailing like this now and fix it properly in autumn. Nothing terrible will happen until then despite you losing 0.1kn of speed perhaps.

[LittleWing77]

Originally Posted by C420sailor

It isn’t iron, so corrosion isn’t an issue. This is a cosmetic/drag issue that can be corrected before next season—don’t waste prime sailing season on it.

+1

LittleWing77

[jamhass]

Painting lead can be problematic, as bare lead oxidizes very rapidly and paint does not adhere well to the oxide. In addition, copper-bearing paints do lead to galvanic corrosion issues which also affect adhesion.

As such, a proper primer and barrier coat is critical for paint life on lead.

There are a lot of threads on painting lead keels, but the gist of it is:

1. grind/sand to bare lead, leaving a good tooth (as from 40 grit)
2. IMMEDIATELY coat with the proper primer or epoxy barrier coat. Timing is important to avoid the lead oxidizing. A trick I have used successfully is to apply the primer with a stiff wire brush aggressively scrubbing it in. This cuts through any oxidation and helps with adhesion. Work small areas at a time.
3. Paint as usual.

If the keel already has a well-adhered barrier coat, don't screw with it, and only rework the affected areas.

[Searles]

It is corrosion it is the lead corroding because if inadequate or incorrect use of barrier coat before high copper anti fouling coatings ,I repeat it is corrosion of the lead keel ,maybe minor but still corrosion .⛵️⚓️