Well, bugger it.
sailingdog and DrB, thanks very much for the info. We were afraid it was a haul/replace issue but we're a bit green and not sure what's "normal"*. Luckily we're on board all week, so we'll keep a close eye.
And now we know. So thanks again.
(And no, DrB, not that type of yard. It's a "you check" yard. We checked, it seemed ok.)
**In my partner's defense, maybe *I* am not sure what's normal. the old wooden troller my dad had always had water in the bilge (and sometimes in other places), a constant diesel smell and various mechanical issues. that was par for the course. Maybe my viewpoint is a bit skewed.