I owned a 1980 Ocean Alexander Mk1 for 4 years. Did a lot of cruising with a young family as crew.
Great boat! I cannot make a comparison for you on the DeFever as I have never been on one.
The OA Mk1 Pilothouse is a true classic and has timeless, salty design that will always be admired. Ours had twin Ford Lehman 120 Hp, so she was slow. They are great sea boats, typical of trawler based full displacement. Wonderful family and entertaining boat. Steering from the flybridge is a joy, no engine noise and it feels like you are under sail.
There were no stabilisers and the first sea trip scared the heck out of me due to the rolling, sea and swell were about 4' to 6'. If you are not used to this, be prepared, you will think the boat will go over, but after a while you get the rhythm and it is not too unpleasant. My wife had a different opinion and would only venture offshore in calm waters. If you can get the OA with original timber work then you will see it is beautiful golden Burmese teak. Unfortunately, a lot of owners have painted over some of these and in my case, used automotive carpeting on top of the teak to “lighten” the interior. It took me days of sugar soap and elbow grease to get it off and then get the teak back right. I assume this is the OA with the Portuguese bridge, and a great layout of pilothouse and galley. We found the design almost perfect, except for one major (for us) flaw and that is the cockpit is way too small for decent entertaining etc. although we still managed to do a lot of fishing. As with all my boats, I added outriggers (small ones) and we landed many pelagic.
The OA can also take a large group of passengers out, just make sure to ask them not to all run to port or stbd at the same time when they are on the flybridge, it kind of makes you, as the skipper, miss a heartbeat. This happened a couple of times when we had friends out doing whale watching. Dolphins and whales love these displacement boats and we often had them surfing at our bow. Full walk round is safe for kids and allows you to make use of so much more of the boat!
The hull and just about all the boat is solid, very solid, thick fibreglass. You will probably find some osmosis below the waterline, no big deal, I had mine sand blasted to get rid of years of anti-foul, repair the blisters and she was fine.
Issues: If the boat has that latrine smell, be prepared to remove the piping/hoses and plumbing for the heads, the smell is caused from both, so better to just get rid of old hoses.
Water tanks are very often rusted and have these checked carefully. Same goes for the fuel tanks, if the forward one is original be prepared that you may have a major job if it is bad. The rear one is easier to get at.
Learn how to handle following seas (no offence if you already do) as you will not out run them, no matter how much horse power you have. Sometimes the reverse gear gets used as much as forward to get into a seaway.
Some came with higher horsepower CAT engines, I don’t think they made much difference to performance, just put a bigger hole in the water.
We had no bow thruster, so although she is a heavy boat, the current, wind and tide make for being very aware of conditions on berthing and anchoring, I got caught out once trying to anchor with little room for error and it was tough.
Ours had full teak decks, forward and cockpit. Many of the screws had allowed water intrusion so be wary of this, especially where you see new screws, check the decks carefully and if there is new headliner, it could mean there were leaks that are still present. Most the windows will have leaked and left stains and will need new runners. They have good pilothouse doors that allow the top half to open while stopping spray from entering the pilothouse. This little amount of spray can cause a lot of water stains and leakage over time, so keep the bottom closed underway.
I never hesitated taking our boat on long trips. An all-round well-built sea kindly trawler, with plenty of room for all the family (3 cabins). One of the best boats I have owned and run.