Our boat and pot? No, nada, nyet. Just isn't going to happen. Just don't bring it on the boat! As ASD stated, it's not worth losing my boat.
Then again, you're not going to smoke tobacco on our boat either. But I don't mind if you bring it along to smoke on shore. Come to think of it, I'd probably let someone smoke cigarettes on board, but only on the fore deck, and only if it's raining like crazy!
On testing; My brother worked in construction. He got drug tested regularly. All random, of course. When he questioned the Super about how often he got tested he was told: "You're one of the few we know will pass the test!"
One of the couples we met in Myer's Chuck, Alaska had a magazine on board his boat with an article highlighted saying that while pot was legal in many states, it was still illegal by Federal Law. They kept it to show guests they weren't just making up stuff when he told them no pot was allowed on his boat because it wasn't legal.
When he went into Canada on his way to Alaska, they did a routine search of his boat. Then they tore it apart for 3 hours. They told him later that when they saw that article, with the highlighting, they just KNEW he had pot aboard.
The think that I found amazing was that they took the time to open up the magazines and found the article! They didn't find any contraband, because there was nothing to find . . . . . but they sure made a mess of their boat.