Mast blisters

[John Manfredi]

My 91 Cat 30 has a factory painted mast. The mast's outside surface has some paint blistering (I haven't looked at inside surfaces for paint or blisters). Blistering is most concentrated around the bottom stainless halyard fittings. Some areas around poprivets on up the mast also have minor blistering. I have noticed this same condition on most painted Catalina masts, but not older unpainted masts. I understand the basic woes of mixing aluminum and stainless; but Catalina Mfg should also understand this and still didn't get it right. So does anyone have a foolproof repair and specific products? Thanks

 

[LaDonna Bubak - Planet Catalina]

Aluminum corrosion

What you're really seeing is where the aluminum has corroded underneath the paint, thus lifting it. Pretty soon that paint will start flaking off. I think it has less to do with the stainless fittings as much as "breaks" in the paint. My guess is that you don't see those "blisters" on the flat surfaces, right? Only where something is connected to the mast, right? That's cuz the paint seal has been broken & it allows water (saltwater?) to enter & cause corrosion. You could catch them at this point by sanding & painting over them with a matching paint or you could let them go & repaint the whole mast sometime down the line. BTW, you wouldn't see the "blisters" on unpainted masts but you still might see some corrosion (rough, powdery areas).LaDonna