This is very interesting. I always wondered if they discussed this before they left with Eärendil. I have read stories where they just left without saying 'good-bye' but people don't often do things that way. It's interesting that Tuor lives on as far as we know from reading the texts [Tuor alone of Men being counted among the Eldar].

I loved the line, so sweet and heartbreaking,

Tuor put a hand on his son's arm. 'You may be correct. I know little of mortals, all the civilization I have known has been with the Eldar. Perhaps, far below the reaches of my mind, my spirit truly believes itself to be of the elven kindred, and in my delusion I shall perish and drown.

I also really like this description of Eärendil.

Tuor looked earnestly at his tall handsome son, in whom the blending of the races of elves and mortals had brought forth a strange luminosity, at once intense and ethereal.

I have read similar descriptions of half-elven characters in fanfiction, but I like the language of yours a lot. Lovely!

I like Tuor's voice above also.

oh, I love this!!

I like this. I like Tuor's calm and certainty, and the connection you make between his having been the messenger of Ulmo and the voyage he plans now. I wonder now if Ulmo appeared to him again on his journey to Valinor . . .