If I were you, I'd negotiate a rock-bottom
price, subject to a test-sail. Trust me, he'll make his
boat "sailable" if he wants it to be "saleable." Even if he has to drive a bung into that hole to get you out onto the
water, he'd be foolish not to do so.
Find out what it would cost to have the hole repaired by a competent 'glas
repair artiste before you begin haggling over the
price. Then, when you return from your test-sail, and if you're satisfied with the
boat otherwise, demand that the cost of
repair be deducted from the low-ball price you'd previously negotiated.
If he balks, walk away. There will always be another boat. And don't be embarrassed to demand that all of the associated paraphernalia be thrown into the deal. Look at it this way: You're doing him a favor to take the thing off his hands, so it's only right that you relieve him of the
trailer,
sails, life-jackets, sailing gloves, any loose
stainless steel parts, and the bucket and sponge so he can write "Finished" to the whole experience.
Good luck!
TaoJones