Pontoon Boat & Deck Boat Forum

I'm looking at purchasing another pontoon.
Found a 2018 Lowe SF 212 with Merc 115hp 4 stroke.

Boat was left in fresh water lake (never in salt water) for 5mos every summer. Stored on trailer 7 mos. This was every year since 2018.

The pontoons have considerable growth on them as well as the outboard motor mounting bracket. Bracket will need to be sanded and painted due to paint falling off.

The growth has a rough texture...when you rub your hand across it, it feel like 80-100 grit sandpaper. It is from water line down.

Owners claimed pontoons were cleaned every end of season and every other season power washed with muriatic acid by marina

What is this growth and how can it be cleaned / removed?

Is this growth damaging to the aluminum, i.e., pitting and some aluminum falling off when cleaned?

Is it galvanic corrosion? How can this be confirmed?


I'm very concerned about this growth/rough texture and its effect on the alum pontoon's integrity.

Thoughts?



Thanks!

This one is out of my range of experience, but I do want to see what folks think!

That stuff pressure washes off much better when you clean it as soon as it’s pulled from the water. Once it dries out; it’s very hand to remove completely.

Should have stuck with just cleaning without the acid wash. That's oxidation from the acid washing and resulting build up from exposure to moisture even in the air. Muriatic acid is great for removing oxidation or the stuff that adheres or grows on aluminum....but in the process it etches it which just makes that stuff attach/appear much easier/faster next time. Typically the thing to do if an acid wash is used to clean off the aluminum is to follow with either polishing (to remove the etched surface) or a coating (to protect it). Think of it like sanding a spot off corrosion of a piece of galvanized metal. Yes the spot now looks clean but the clean spot is now unprotected bare metal opened up, prepped, and ready for whatever so without coating it with some zinc cold coat or something it's just going to look worse....much faster than it took the first time.
https://www.auroramarine.com/main/ask-t ... m-pontoons

That said, oxidation is how aluminum protects itself. It's not like rust on iron where the metal is actually eaten away and aluminum doesn't degrade because of it. I can't say if the stuff on those pontoons are from them not doing a good job of rinsing off the acid wash afterward in which case it keeps eating at the metal. If it's just chalky but still smooth metal underneath it should be sound, and it hasn't been in salt which WILL cause aluminum to pit and corrode.