He doesn't own the boat, he's only thinking of buying
OP If it is a genuine crack, it's possibly a pretty serious one.
But impossible to tell from a photo!
I'd go with a good torch and have a proper look and try to get surveyor
, broker or owner to poke something down inside to get an idea of crack's depth
. (Wouldn't do it myself.)
Some cracks can disappear with a bit of a wipe with a rag given it's only a bloody photo
. Might just be a rust stain.
No one can really tell how big a job it is nor what the crack represents till it's pulled apart after lifting the mast.
And no matter how it's done lifting the mast is a big job as it will also involve the deck
If I were selling I would get it fixed.
If looking to buy like you are, I would just walk away.
Couldn't tell from the photos whether encapsulated or bolted keel
, but if it is a crack, how deep does it go? So very difficult to price
such a job, as it will take as long as it takes, and more issues may become apparent as the mast if lifted and the top of that step is cut away.
And then there's that other burning question, wtf caused it to crack? You might go to all the trouble of fixing it and in 12 months time it splits apart again. But it may be really trivial.
Oh, and if I were selling, I'd wipe it clean, fill with epoxy