Thread: making my alicraft watertight

Originally Posted by Allgood

Try painting the boat inside and out from the keel to the waterline with something like this...... https://www.liqui-moly.com/en/nz/und...1442.html#6113
Turn the hull upside down when applying it to the outside so it can flow around/into the rivets/joins.

Again, I'd be reluctant to paint an older hull just from past experience (which was dramatically terrible - the coating actually created a lovely corrosion stop and the hull blistered under the coating in months). I would think you would need to surgically clean the thing and then etch prime it to get the coating to stick - and you may still end up with places where the coating just sheds like a snake skin. Ali is an utter pig to get paint and coatings to stick to, especaially when it's been around the block and contaminated for 20 years. It's bad enough brand new!

One of the issues with old ali that isn't sealed (like riveted dingy style designs) is the joints trap moisture and oil and crap and painting over the joints means that you've created a dissimilar metal contact point or to put it another way, a really inefficient battery which is really not what you want with a reactive metal like ali that gives up so readily in corrosive environments.