A good story overall. For me, predictability of the plot got in the way of putting this one down as a Podcastle classic. As soon as the poisonous flowers were mentioned, I said "they're going to poison the mermaid's tea party and hide it with honey". "Callico" Jack (at least that's what I call him) makes an engaging character, with just the right mix of crazy and caring. With such a character, you knew he was destined for a tragic death, though. After all that, he wasn't just going to live happily ever after.
One thing that did bug me, though, is why they didn't think to make some sort of shelter on their raft. Jack, we assume, is a capable sailor, and so must have known their odds of survival were much better if they could stay out of the sun. You'd think he could have wove some of the palm fronds as hats or umbrellas, and use the mermaid's hair as rope. Of course, he was half-crazy by then, so meh...