Hi Vickie and big thanks for the info and pics.
We've just bought our boat, integral water tank was empty so filled and sterilised then flushed through a couple of times to get rid of brown colour (suggesting that there is no coating??)
It still has a slight taste to it even after being filtered and am looking at the options for coating the inside - assuming I'll be able to get the cover off!
Seems to me that a couple of coats of vactan, properly cured, is the way to go, at least in the short term, then check it every time she comes out for blacking. Just been blacked so won't be coming out of water for a while (insallah!!) so looks like it's a job for later in the year.
Thanks again, a really useful post.
Steve