It depends on whether the trailer and tires are rated for the weight of the boat. Back in 1986 the new O'Day 192s, 222s, and the 240s were being sold in the boat shows with single axle trailers. With that said though, I think that a boat of that size including my O'Day 222 should have a tandem trailer under it. If you're trailering a short distance, I think a single axle would suffice.
A friend of mine has a single axle bunk trailer under his Seaward 22. The only problem you can run into with this type of trailer is getting it deep enough to float the boat on and off at the ramp. He has a 10' extension tongue that he has to use in order to get the Seaward to float on and off the trailer.
A shorter roller trailer with keel rollers can be used on an O'Day sailboat, but
rollers can be a pain when the pins get bent or rust up and they cause the rollers, particularly the keel rollers to bind up. The cost of replacement can nickle and dime you to death.
However roller trailers can allow you to launch at almost any ramp and this is great if you do a lot of trailering.
If on the other hand you have a mooring or a slip, you're better off with a tandem bunk trailer that will take a 24' boat and this trailer can be a powerboat trailer which is rated for the weight of your boat. The trailer will be longer which will allow you to get it in the water deep enough to float the boat on and off it at the ramp without an extension tongue.
As far as converting the trailer over to accommodate the height of the boat sitting on the trailer due to the keel, all is needed are longer extension brackets under the bunks and a couple of planks sandwiched together for the keel to sit on. That's it.
My trailer is a Long Mfg Aluminum tandem powerboat trailer that was made for a 23' boat. I used 24" extension brackets to support my bunk higher. For the keel boards I used a couple of pressure treated planks and two galvanized power company lightning arrester brackets to hold the planks to the galvy cross members. No holes were needed in the cross member for these planks. The brackets can be loosened and the planks can be moved from the center of the cross members to either side on the trailer.
The only other thing that needs mentioning about O'Day 23s is that from 1970 to 1973 these boats were manufactured with cast iron keels which created a lot of rust issues that caused the centerboards to bind up in the keel slots.
A lot of guys have these boats and have accepted the challenge of correcting the problem. In spite of the issues of these older O'Day 23s, these are still nice boats if one is willing to meet the challenge. If not, I suggest that you find a later model O'Day 23.
Good luck! I am at Destin, FL this week. The beach is awesome but the surroundings have me wishing I could be sailing.
