Binary Cursors (& Geometric Type Support)

I'm trying to port some code from C/libpq to Java & one of the things
I'm having trouble with is getting binary cursors to work.  The C code
uses a binary cursor to speed up a loop through a bunch of polygons & I
was hoping it would have the same effect with Java.  The code for a
non-binary cursor works fine, but is just taking too long.  Basically,
here's what I'm doing:

query.executeUpdate("declare my_cursor cursor for select p from
my_polygon");
ResultSet rs = query.executeQuery("fetch 1 from my_cursor");
PGpolygon p = (PGpolygon)rs.getObject("p");

When I switch the "cursor" to a "binary cursor", I get the following error:

Conversion of point failed - java.lang.NumberFormatException:
??n?gk@A?z?v A?OT&?A@A

Is there something else I have to do to get this to work or am I going
to be out of luck?  I've seen references to people successfully using
binaries cursors in earlier messages in the list -- is it just the
non-standard geometric types that are troublesome from a binary perspective?

Thanks,

Jeff Hoffmann
PropertyKey.com