Scraper
From KayakWiki
Sometimes called a cabinet scraper due to its use in furniture making.
A scraper is a thin piece of hardened steel used to cut away a very thin layer, leaving the worked surface very smooth. The blade is sometimes held in a handle or a doo-dad that looks like a plane. Mostly though, they are just held free-hand.
Use a flat blade on the outside of a curved surface (your kayak), and a rounded one on the inside.
Here's a couple of sites with some good general information on scrapers and how to use/sharpen them.
