Both are great boats
Peter -Both of the boats you are talking about are great boats. The 17 foot boat is the O'day daysailer, a respected design with good performance and stability. The Mariner gives you a couple of more feet and a small cuddy cabin. The centerboard is metal so you have more ballast and the boat is harder to capcize. The Mariner also gives you the option of a fixed, ballasted keel, if you find the right boat.Either boat would make an excellent beginner's boat as you learn to sail. If you plan to bring your daughter, however, I'd opt for the Mariner and I'd find a fixed keel boat if possilbe. If not the centerboard version is a close second. The cuddy gives your daughter somewhere to get out of the sun and the ballast will make it a lot harder for her to get wet.Justin - O'day Owners' Web