Not Waving but Drowning

This poem had no rhyme scheme and some of it's lines didn't flow very well. Such as in the second stanza where it says, "It must have been too cold for him his heart gave way,".
As for the meaning of the poem, I believe it is meaning that people sometimes try to hide the bad things in their life and make it seem like everything is okay when it's not (I think we talked about this in class). This idea is shown in the poem, especially in the first in last line, "Nobody heard him, the dead man, - And not waving but drowning." I thought the last line was interesting, it brought the visual of when you are on the beach and you see someone in the water, waving their arms, like they are sending a friendly, 'hey there' to their companions on the beach until suddenly you realize they're not actually waving their arms in greeting but in terror, asking for help because they are drowning.