Also how do I finish off the radius'd edge. As normally a rectangular
piece of wood is used as an eding piece to a straight part of the
decking.


(Sorry if this appears twice, but the first hasn't shown up on my computer)

Don't know about any of the other, but to get a rounded end, the best bet is
to use a boat building technique, 'Cold Mould Ply'. You will need 3 mm
Marine Ply cut to the depth you want it on the edge in strips. Nail the
first one on to whatever timbers you have, to form the basis of the curve.
Apply a good layer of glue and then fix another on top, your thickness is
now 6 mm and keep on working up to the thickness you require. Each layer can
be nailed so the heads of the nails are flush. The top and final layer,
don't drive the nails right down because once the glue is set, you can
remove the nails and then put the sander over it all to get a finished fit
for staining/painting/varnishing or whatever you wish to do.

Racing Yachts, Power boats and even a Lifeboat was built using this
technique. If you are old enough to remember the 1979 Fastnet Race where
lots of boats sank and people died, there were two racing yachts, Golden
Apple and Silver Apple in that race and although damaged, they returned home
:-)). They were built using the Cold Mould technique :-))

Mike