Re: Thoughts on a 86 sea ray seville? Are these decent boats?
I have an '88 Seville 20' bowrider. I bought it last summer. It's performed flawlessly for me. I have the 205 hp 4.3 liter V6, so the power is about the same as your 170hp on the 18 footer. I love the way the boat performs. I checked out the floors by rapping on them with a small hammer I brought along. Along the chines, across the back in front of the engine, in the ski locker, under the engine, across the transom. Everything checked out sound from what I could tell, and I've seen nothing to change that opinion. But these boats vary a lot, so check your's out. If it's been trailered and covered properly, there is a good chance it's fine. I'm in California, so it's a pretty easy climate for a boat. Don't know where you're from, but if it's the mid-west (winters, humidity in summer) or South (humidity), or if the boat has been kept in a slip, check floors especially carefully.
The condition of the upholstery should help you understand if the boats been properly covered. Dash guages should be easy to read, with no staining on the faces, and no moisture inside the face.
Engine should be clean, bilge under engine shouldn't be oily or dirty, hoses should look good (not dirty, checked/cracked), paint should look like original color, not dirty all over. Some staining is ok, the boat is 25 years old, after all. Oil should not have a burnt smell, or be very dark and thick. Does it have an hour meter? A well kept engine can last several thousand hours, one not maintained can be old at 100 hours.
Bellows on the outdrive should be in good condition. Cracked shifter bellows can sink a boat, exhaust isn't as important. Cooling water is, of course, very important. If the PO can't show you a record of when the impeller was changed, plan to do that or have it done very soon.
Good luck, these are GREAT boats (of course I'm biased) when they are maintained properly.