Damaging living Spelljamming ships?

Maybe this is something that I've missed somewhere in the rules,
but how are the rules for damaging living ships different from
those for non-living ones?

Disintegrate is listed as doing one hull point, for example,
which presumably applies to both living and non-living ships, but
should a living ship have a saving throw to resist this damage? I
would expect the larger elven ships to have quite good saving
throws!

Reversed Heal, Harm, has no obvious upper limit (in theory it
even afflicts 300HP+ dragons or divine avatars), so should affect
living SJ ships, if the DM is generous leaving them with one hull
point.

Would it make sense to say that as a vessel is starting to loose
function once it has lost half its hull points then this is
logically equivalent to a creature having zero hit points? So, a
Harm spell does half the hull points of a (living) vessel, and a
second one destroys it?

You can then say that appropriate healing spells that work on the
sort of creature that the living ship is can restore hull points.
Two CLW for a hull point, a CSW for a hull point, a CCW for two
hull points, and a Heal for half the hull points?

Does this make sense?

-- 
Dreamer
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