Thoughtful writeup, without unneeded drama. Much to think about indeed.
Like any boat (or plane or house) that sat for years, closed up. projects do multiply. We knew we were buying a fixer upper when we acquired ours, it having sat in the moist salty air of the Alameda Estuary for three years closed up tight, after being beat up well in a big sailing club in SF for three years. But all that "knowing" loses some luster when one is dealing with mold-filled cushions and fabric hull ceilings that smell of mold and mildew, with stains to match. We did have a few "what have we done?" days......
Remember about the "elephant" tho -- you only have to eat it "one bite at a time."
If the rig is sound and the diesel runs OK, and it has basic sails that function up to maybe 15 knots.... go sailing often.
Cherry-Picking your list a bit: Water tanks are meant to be filled from inside the boat. Bring the hose in with a little 'gardening' ball valve on the end. Works very very well. And no deck fill with rotting O-ring to sweat over and no fill hose to replace. We wondered at that scheme initially, and then immediately liked it.
Charger: EY was installing a ferro-resonant type charger in that era. Notorious for boiling batteries dry. I replaced it with amore modern multistage solid state charger. first thing. Changed the install location too, to starboard side. Details if wanted and photos.
Datamarine: yup. Faded faces and mostly worked... replaced with Raymarine ST-60 set, about 1995. Still working like new.
AP: We started out with an Autohelm system and thru two upgrades are now at a Raymarine system. Still a wheel drive, and as Christian had pointed out these are sufficient but not really for blue water if you head for Hawaii. We like ours, but do not make too many demands on it. Vital "crew" however. We named him "Otto Von Helm" because he takes orders and carries them out stubbornly without comment.... so you have to keep an eye on him all the time!
Universal Diesel: I was having to glow plug ours about 15 seconds on a cool morning, first start up. 20 to 25 when it was 30-ish out. We had about 2300 hours on it. Worked fine, and I had learned to deal with its maintenance details. It was burning about a quart of oil during the last couple of seasons and was leaking out of a rear seal. The much-maligned Hurth transmission worked flawlessly but I was planning on replacing it anyway, as their rebuild ability seemed questionable. If you read my blog entries here about our Betamarine25 install, note that I could have pulled the old drive train out and rebuilt the engine, changed out the torque plate, replace the panel and all wiring, and replaced the transmission. Figuring on a note pad, the total for that would have easily surpassed half or 3/4 the price for the new Betamarine. But I am not a competent engine rebuilder. I am strictly a parts-changer.
You note that you would need access to the underside of the cabin top. Tedious, but not too difficult. Remove the teak battens, and then using pliers and other little tools, pull out staples until you can gently lower part of the vinyl headliner. Some swearing will be involved.
Be sure to epoxy-fill all holes thru the cabin top or deck before installing new hardware. I have a blog entry about installing new winches and clutches. Marvelous Upgrade !! imho.
Not mentioned specifically, but do a deep cleaning under the settees, the engine, and under the sole. Replace all the head hoses. This will restore much joy to the whole experience. This will be true, IMHO, for any boat of most any age over about 15 years old. I have crewed on a lot of deliveries and really come to dislike entering the cabin and being assaulted by "head, diesel, and bilge" odors. Make of boat unimportant.
(Sigh...) So Many.... owners do not replace old hoses and keep the place
cleaned up. I value all of my delivery ocean experiences, but the downside was spending time inside trying to sleep on smelly cushions and use the head compartment at 3 am..... sometimes almost holding my nose. Sorry 'bout that -- rant over.
Hull fabric. Oh My---- if I had realized how difficult it would be to replace it down the road, I would have gone over it ten times more than the twice or three times I did clean it with a rental carpet cleaner unit. That fabric will endure 'til the end of time, if only you keep it clean. it's really durable material. The adhesive behind it is super good stuff also!
Anyhow keep the questions coming and do lots of searches on this site starting with Olson 34 and adding words.
The thru-bolted hull/deck joint alone raises it way above most lesser boats with glued or riveted "shoe box" joints. And, having all the interior pieces
tabbed to the hull and deck is really a solid way to build out a rigid boat. It compares very favorably against the EY system of glassing their hull and deck together on the inside with roving. When it comes to "good bones" these are sturdy 'bones' indeed.
