260 Weekender won't hold course

This is my first single i/o... I'm used to twin inboards. Does this setup have inherent difficulty in maintaining a straight line at low speeed? I tried adjusting the trim, but it does just loves to wander. What gives?

Most single i/o love to wander. Tell us a little bit more about your setup, engine, out drive, so we can help.
Since this is your 1st post you many want to add your boat info to your signature section. Some people will not respond if you don't have that.
ps: Welcome aboard.

Welcome and yes, Chuck is correct, if you're used to twin inboards the single I/O will seem exaggerated

Thanks... Wandering is normal? Nobody thinks this is a bad idea? What can be done? This is a stock 260 (except ss prop, the purpose of which escapes me). The power to weight ratio does not suggest this thing will haul.

Other concerns. This rig maxes out at about 3400 RPM and 18 kn (GPS). I believe that's about 1000k and 8kn short. My first reaction is to go back to the wheel suggested by the mfg and deep-six the stainless thing.

How accurate are those old gauges? Oil pressure reads barely above the low mark and doesn't move much at higher rpm. Could the tach be off as well? The boat has been serviced regularly and was bought from a very reputable senior staff co-worker

The boat itself is nicely-thought out...little things that make for a pleasant experience. Lights in the right places, no head bangers or shin scrapers. Storage everywhere. One exception is the goofy cut-out steps down to the cuddy.

I'm used to side decks and better-placed cleats, but small is a compromise. This one is nice for the designed purpose and doesn't cost me $200/hr.

I want to install a 6kbtu ac and would like to know where the mfg installed them. I want to guess under the dinette seat aft as the area adjacent where the step-down pump is located looks about perfect for the inlet/strainer/pump. The only other choice I see is under the vee, but that would be a bit noisy for sleeping.
Thanks... this is a great site!

Hang in there, you can make things better. Your boat is 23 years old and may have skipped some maintenance and upgrades. You can also change some stuff.
First, the 26 Weekender is a great boat. It is well laid out with more cockpit room than most others, plus nice interior - without a lot of extras. The ride is usually nice with a low center of gravity.
First you need to resolve that serious engine issue. Is it the original engine? It could just be shot - maybe running on 4 cylinders. Get it tuned up and make sure it runs and makes 4600 rpm in neutral. Find out what exact prop you have and see what condition it's in. A stainless prop helps this boat and engine because of that power to weight thing you mentioned. You'll probably use a 15 or 17 in prop. Check what's on there. If you can't make full revs with that you'll have to find out why.
You should get a lot more speed and probably more efficient mileage. The boat will track much better when you can give it 2 more miles per hour.
As for the guages, you may have to replace them. They're not really expensive or hard to change. You can buy them individually. Oil pressure could need a new sender too.
You can't rely much on the speedometer but you say you're using a GPS for speed.
These can wander a little, but the Weekenders in those years were pretty deep-v so they are better than many boats and run pretty straight. At speed they will run straight.
Good luck.

Let me add, I agree about the cleats. I think it's a Searay thing. I added two on the transom for securing at the dock. I want to move 2 cleats forward just ahead of the cockpit for tieing up. They currently are so far back that the boat wants to spin with one line on. This will pull it right into the dock.

The wandering is normal. It's caused by pressure created by the spin of the prop. The pressure builds up on one side...releases and builds on the other side and so it goes...not much you can do....sorry...

Many reasons for the stainless prop. Just check to make sure it's the right one. I'm going to assume that you have an Alpha? Larger drives, TRS, Bravo etc, usually don't wander or wallow. I think they have a larger "rudder" effect. Also, a 4 blade SS prop has more bite to reduce the wander. Proper size of course.

Install a manual oil pressure gauge to identify the gauge accuracy BEFORE replacing parts. Yes, by all means find out why it won't rev!
Do a leak down test, or have one done. Or a compression test. Sounds like it may be tired.

Dirtguy, I just sold my '82 Srv 260SXL to a friend. Can you post some pics of your boat? I had a single OMC 260 with 800 Stringer drive. I bet that 460 big block really moves that boat!
Great boat, not many of them ever built.