Mike,
Are you looking at a Mariner 2+2 or the regular 19?
I have the Mariner, and it is a great little fast boat. Keel leaks are from the center board pivot bolt, and an easy fix. Parts are readily available from Rudy at DR Marine,
http://www.drmarine.com/. The Mariner has a fully retractable centerboard, where the 19 has a center trunk, which sticks out from the bottom of the hull about 6 inches. You can beach the Mariner no problem.
This is an old manual I found on the Mariner.
http://documents.clubexpress.com/do...kI5NPFXvqtrywefXKdwtBHwm+12wbhZImL2X7wC2uSFb5
A few points about the Mariner:
They are still made by Stuart marine, so it's a well proven design,
Light easy to tow, set up, get in the water sail, then take home again,
Ok to spend a night on with kid, or one other person.
No core fiberglass! Easy to repair.
I had a link to Nathan B. 's website, "the boat Orion". He has several write ups on some common fixes. Google it, very helpful, even though his boat is the older classic version of the Mariner.
Hope this persuades you to restore and preserve yet another great O'Day!