Don White wrote:
Peggy...here on the east coast, we discharge the heads through the hull.

There are no coastal (or inland) waters in the whole US--east coast,
west coast, or Gulf--in which it's legal to discharge raw untreated
toilet waste directly overboard or dump a tank. So unless you're only
using the the head when you're out to sea at least 3 miles from the
nearest point on the whole US coastline, or it's going through CG
certified Type I MSD (device that treats waste before discharging it
overboard) first, you're discharging it overboard illegally.

If I bought a modest sized sailboat inland that might have a chemical toilet
with a pumpout fitting on the deck...
how hard would it be to convert to a thru hull discharge?

You'd only have to install a y-valve in the pumpout hose, and a line
coming off it that goes to the through-hull, with a macerator pump
inline to empty the tank.

Would I have to tear the old head out and buy a new one?

Nope.

Peggie
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Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html