[whpalmer4]

Okay, for a mere 5% of the savings, I'll give you the answer :-)

Go to the Project inspector. Click on the 4th icon over (looks like a little original Mac with a checkbox on the screen) to bring up the Project Formatting section. There you'll find the conversion factors that OmniPlan uses to convert hours to days, weeks, months, etc. In your case, 12.0 hours per work day, 84 hours per work week should do the trick. I made a trivial plan from your data which showed 23w4h duration with the standard work week and 11w when the conversion factors were set as described and the work week set to 7x12, so I think we both learned something here :-)