What's this on my hull, and how do I remove it?

[Woodchuck]

I have this stuff on the bottom of my hull. The Porter Cable polisher and 3m restorer and wax doesn't remove it. Any ideas on how to remove it? Do I just need to spend more time with the Porter Cable? It removes a lot of it, but there is still some you can feel.

 

[dan144k]

Is it at the waterline from storing the boat in the water?

 

[Woodchuck]

It is below the water line. I assume it is from storing in the water. I tried simple green before the polisher.

 

[MOA_Chaser]

Did you try any rust remover/muriatic acid?

 

[Murf'n'surf]

Looks like a growth of some sort. Can you confirm that it is on the surface and I'm not seeing cracks in the gel coat?

You'll need to use an acid to remove it. On/Off is a common hull cleaner widely available. A pressure washer may blast it off as well but be careful not to burn holes while p-washing.

 

[Woodchuck]

Looks like a growth of some sort. Can you confirm that it is on the surface and I'm not seeing cracks in the gel coat?

You'll need to use an acid to remove it. On/Off is a common hull cleaner widely available. A pressure washer may blast it off as well but be careful not to burn holes while p-washing.

Yes, it is on the surface. I can try the pressure washer, but I bet an acid will be required. It is on there pretty good.

 

[txav8r]

Try LA's Totally Awesome from the dollar store...it is great with organic compounds. Just spray and let it set 10 or 15 seconds, then use something that won't scratch the gelcoat but with a mild abrasive surface to wipe it off. I like the sponges that have a nylon mesh over them, called a Chore Girl I think...those are old school, you may get good results out of a magic eraser too, but I don't think with the Awesome, that you will need more than something with just a little texture to it.

 

[Woodchuck]

I tried the On & Off and it didn't touch it. I haven't tried the Totally Awesome yet. The On & Off did remove the rust stains around the cleats.

 

[Bennie]

I recommend.... a trailer.
Sorry bud - couldn't resist.

 

[OrangeTJ]

I just used JJVS best to get the scum off the bottom of my boat. Kind of pricey but worked well. If you have a galvanized trailer, be sure to get it totally wet with water before spraying on the cleaner though. I didn't and now my trailer is totally marked up from the spray. The trailer is hideously ugly anyway so I am not that torn up about it!

 

[Murf'n'surf]

The On/Off needs to sit and work for a while.

 

[Woodchuck]

It is on a trailer. I'm trying to clean up the previous owners mess.

 

[Bennie]

@Woodchuck - just a quick question (seriously). Is this all over your boat hull (under the water line) or just in one place?

The picture shows a lot of rather sporadic lines and I would venture to say that marine biological growth would tend to colonize (like moss or barnacles) rather than be wide spread. A wide spread "injury" like that is normally due to more a general atmospheric assault.

 

[Glassman]

The On/Off needs to sit and work for a while.

What do you think Murf, time to break out the Sno-Bowl?
Hey, it's on a trailer...

 

[Murf'n'surf]

It's worth a shot but On/Off is a lot stronger.

 

[MOA_Chaser]

If muriatic acid doesn't take it off, chemicals won't work. Just be careful of your trailer when you're using it.