strange question on toon cleaning

[dewe48]

I bought this boat used a couple years ago. The former owner had it in a canal and told me he put something on the toons to make it easier to clean. As you can see from the pictures, it looks like something was brushed on. It cleans up with sharkhide cleaner, but slowly comes back, even just sitting out of the water in my hoist. Even when it's clean you can still see the brush marks a little. What could this stuff be, and how can I get it off?

 

[dewe48]

No ideas? Could this be old shark hide protectant?

 

[steelespike]

How do you clean it?It sure cleans up nice. You might ask around on the various pontoon forums on the net.Let us know what you find.