Work boat.

I've hooked up with some friends that want to study fish farming out at sea. We've come up with various ideas we want to try including a fish farm you tow behind a boat, or one of the aquapod style geodesic sphere farms that can be anchored below the surface. We want to study doing this far out at sea perhaps anchoring on a sea mount or free floating fish farms that circulate in currents. What I'm looking for information on is the kind of work boat that will take a crew of 5 or so out to sea and back, tow equipment perhaps operate an ROV , lower and raise cables etc. What's a good lowest cost option for a work boat that will handle being far out at sea doing this kind of research?