The vessel for a nursery rhyme trio would be a “TUB”. A tub is a container that is generally used for holding or storing things, but it can also be used by people for bathing or washing. It is typically large and round or oval in shape, and made of materials like plastic, metal or porcelain.
Now, regarding the clue itself, the reference to the “nursery rhyme trio” probably refers to the well-known song “Rub-a-dub-dub, three men in a tub”. This is a famous nursery rhyme that tells the story of three men who go to sea in a tub. The rhyme goes like this:
Three men in a tub,
And who do you think they were?
The butcher, the baker,
All jumped out of a rotten potato!
Turn ’em out, knaves all three!
So, in this case, “tub” refers to the container that the three men are sailing in. It may not be a very practical vessel for sailing, but it certainly makes for a catchy and memorable song!