Couple things... YES you can trailer launch the J/24.
You have to find a more robust wheel for the dolly.
you also must make sure the boat is forward (tongue heavy) on the trailer... some will place a secondary dolly on the aft section of the trailer (insurance)...
The procedure goes like this.
back to the water, not in... put in wheel chocks....
leave safety chains on... unhitch trailer.
lower trailer to dolly.
wrap strap from tow vehicle to trailer... remove safety chains... pull tow vehicle forward, remove wheel chocks... back trailer down.
This works great as LONG as the ramp is long (very long)... and is sufficiently steep to allow you to not run out of strap before you float the boat (like was said you need deepish water)... 4' keel roughly 6-12 inches off the ground (its sitting on a trailer after all), so think about 5' to get you floated.
I do this every season... I do it solo.
NOW... you are floating, but you still have to stick the pole. That's a keel stepped mast, and honestly you have 2 options if the club does not have a crane.
A large A frame, or what the J/24 folks call a GIN pole, but it's really a secondary mast. You basically setup a 20-22 foot high 3 stayed mast... with a block on top... run a line/halyard up it, with a bridle around the mast for the J/24, looped around the spreaders (I hear that you want to run to lower lines to hold the loop down, and pull the line back down once the mast is up)... I don't have to do this, as I have a deck stepped mast... but 2 of our J/24 owners do this. Anyway, with 1 person lifting the mast (with the secondary mast halyard) 2 others steer the foot of the mast into the slot.... Again you MUST have a secondary mast or A-frame that sits HIGHER than the mid-point of the mast.
Once the mast is lowered into the hole, one person goes around connecting shrouds...
IT ALL SOUNDS great, but it's a scary way to raise a mast. DECK stepped masts are easier (IF) they have a hinged mast step.
Again, deck stepped with hinged base is much easier... I did this myself.
And don't let anyone tell you an S2 7.9 is faster than a J/24.
its not.. they are close... The S2 7.9 is a better heavier air boat than the J/24, in light air the J will eat their lunch... and in light air I eat both their lunches, and I am rated MUCH slower than both.
The S2 7.9 is a good compromise boat, and it's a ton easier to launch than the J/24 or the Capri 25. Its heavier built, and probably #1000-#15000 heavier than the J/24 or the Capri 25.
The Left Coast Dart is also an expensive option and a great boat, based on the core of the B25 (also a fun boat)... the B25 is a twitchy little boat, considered one of the first sport boats actually.. its a TRUE Ultra Light Displacement boat, and requires attention to minute detail to sail well to its rating... I submit that the Left Coast Dart probably does too... both sweet racing boats.
Personally, going from a Catalina 22, I'd suggest going to a J/22 or a J/80 to race on. Easy to find tuning guides, and a lot of boats to buy that are in decent shape.. the J/22 would be a much easier transition for you as well. It's a deck stepped mast, and a lighter boat than the J/24. Yeah used its a bit more expensive...
