YOYO!, My thoughts exactly.
http://cgi.ebay.co.uk/Boat-Seat-Idea...QQcmdZViewItem
Some of my friends made seats with Decking wood for their rib, all I can say is that they were dangerous, ugly, took value from what was already a piece of shite and I just would not go out for safety fears.
If you were not getting a Ceder whopping on your butt, you stood the chance of a belt in the ribs with same.
On the whole, it was sore I believe. He managed to putseveral people off boating so far. Take my advice, spend the £1.80 or £2.10 or whatever and do not build your own.