I have a power steering fluid leak in my boat, any suggestions where it might be coming from?

I have a Volvo Penta 5.0 motor in my 186 ssi 2000 chaparral. I ran the boat today and found that the leak is coming from somewhere in the back of the motor. I found fluid gathered up around the rear engine mount but was unable to position myself to find the actual leak. Does anyone have any suggestions what the problem might be and how much it might cost?