2009 aluminum corrosion?

[Doubletyee]

I am looking at buying a 2009 aluminum boat and it looked good until I climbed under it and seen all these marks. Does anyone know what might cause these? I was thinking barnacles and then pressure washer off. Does this affect the hull? Or is it corrosion? There are a lot of guys who know there stuff here and would appreciate your comments. Thanks

 

[zurk]

white patches on aluminum is normal. leave it on. its a protective layer. i would paint over it with 4-6 coats of interprotect 2000e.

 

[MikePA]

Looks like removed barnacles to me

 

[trophywife]

barnacle left overs for sure... alu corrosion looks like heavy dimples and or white powder.