scupper holes

 Has anyone ever tried putting more scupper holes in a kayak?   Im thinking about drilling new scupper holes in a malibu 4.4 and using pvc as the shaft and then melting plastic over the pvc to seal the boat back up.
 has anyone done this kind of modification to a kayak?   any ideas?

If it ain't broke, don't fix it.
I have done a lot of modifications but adding a scupper hole is something I personally wouldn't attempt.
If you were a ways out and something went wrong with your plastic weld or the connection point between the yak and the PVC you would be in a world of trouble.
I do not mind drilling holes in the top of the yak, but never in the bottom.

...you are a brave man 

I have an old OK Scupper that has been repaired including on one of the scupper holes.  It was repaired by the former owner who happens to curretnly be advertising for kayak repairs on Craig's list.  Try this link http://monterey.craigslist.org/boa/214761765.html .  If nothing else, Joel can probably provide good advice as he has significant experience making repairs on poly boats.

 The boat isnt broken but it could be fixed.
 The boat has a amazing glide and responds like a boat much shorter than its length. Long, but could be a great surf boat,  except for the fact that it cant recover after being swamped and the boat does not appreciate the load, even in flat water.  The rear scupper hole it set above the depth of the seatwell, so it pools.
 If you are using a seat that is more than  just a backband, this hole is obstructed anyway.
The foot well hole is in a good spot but is far to small and seems an eternity to start draining.
Other than that it feels like they made the boat for me.
The solution seems to be 2 more scupper holes placed behind the foot well hole.

thanks for the link ill check it out.
 

I can see your problem.  But, as has already been pointed out, the bottom must be perfectly sealed.  A new boat that I boa\ught had a pinhole in a manufactured original scupper.  That boat took on enough water to make it act badly.  The dealer replaced it.

I would do a test bond with scrap polyethylene and pvc before attempting and significant welds with it.