Alumacraft corrosion help

I have a 04 Alumacraft Navigator 175 that I bought new. We have taken excellent care of the boat which these last 3 years having seen very little use. I was cleaning it up the other day and noticed on the transom two spots of corrosion about the size of a .50 piece, one on each side of the motor about by the waterline.

Any ideas on what I should do to fix the two spots before they get worse? At this point the paint is basically bubbled but over time it will just get worse. I didn’t know if this was an easy fix or something I should try and have a pro do. With that said any shop recommendations in the north metro?

Thanks for any replies, tips, or comments.

WS

I have a 2016 Competitor 185 manufactured in 2015. I have same issues including the 4 splash-well drain holes that have corroded to the point that you cannot even stick a pencil through them. The cause is that manufacturers’ Lund and Alumacraft (maybe others) were using marine wood treated with wood preservative containing copper, copper is reacting with the aluminum etc. Alumacraft are taking no responsibility, I found one person who actually had his transom rebuilt for free by Alumacraft, but now they are denying any responsibility despite 10 year warranty on hull. Lund are rebuilding transoms, admitting to the issue. Both companies switched to composite transoms for the 2017 model year.

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First you need to find out if it is coming from the inside or was caused by a chip in the paint. Take something sharp and poke at it pretty hard if it does not goes thru then chances it is from surface damage. take a small grinder grind out the oxidation coat with epoxy primer, at this point you have a choice either just put some paint back on it or fill the area. If filling use Marglass it can take being wet sand prime and paint using matching paint which can be had from most automotive paint stores.

I had this issue on my 2000 Crestliner 182 TS where all the snaps were installed for my cover had to pull the snaps and repaint my drip rails.

I would check your transom to see if it rotted. You will need to fix that before you fix the bubbling.