Cutter rig

[hpeer]

Union 36 Boat Review - Practical Sailor Print Edition Article

As cutters, most Union 36s were rigged with self-tacking staysail booms, although many owners have opted to free up the foredeck by removing this spar or replacing it with a roller-furling unit. Perry recommends sailing with a genoa and without the staysail to maximize light-air performance.

Bob Perry, who designed the Union 36, is active on Sailnet and usually very accessible. They have a thread on them.

[Cheechako]

To me it's timing. Majority of the time the headsail will tack across the staysail stay fine. It's all about timing when you come about with how much and when you release the jib sheet. Practice, you'll get it. Use sheets without a big knot at the clew also.
Basically, just as the headsail starts to backwind a bit, you release the sheet just enough so it fills between the stays, the power of the wind is then in that concave "bucket" , then release and it pulls the sail right through.