What's going on here? What's the black stuff?

[Darrow]

Looks like a chunk of wood melted to the hull. The black stuff is hard as a rock. It was under the fuel tank.

[psk125]

Maybe a chunk of wood set in epoxy to position or support the fuel tank.

[deblen]

Maybe https://www.amazon.com/Marine-Tex-RM...23138692&psc=1


or Monkey poo/duct seal

[Franziska]

Originally Posted by deblen

Maybe https://www.amazon.com/Marine-Tex-RM...23138692&psc=1


or Monkey poo/duct seal

Possibly this stuff to fix a hole in the hull?
Someone not knowledgeable might have done it.

[deblen]

OP said it was "under the fuel tank" & it looks like a wood board is embedded in the black stuff.
Just a guess but could it be that the tank installer placed this under the tank as a shim during original install.

[JPA Cate]

The Marine Tex we used dried pale blue. Didn't know it also came in black!

Sorry to say, I don't know what product is in the picture.

Ann

[Darrow]

It was definitely a shim/base for the fuel tank. It had some screws in it to attach a flange on the tank - was more curious about the product/epoxy/monkey poo lol

[AKA-None]

Aviation form a gasket
Might have been the closest goop
It’s black and dries hard exposed to air
More of an adhesive than most gasket goop, that’s a technical term