You might want o consider making a traditional Japanese adze. They would
scale up easily to the size needed by ythe Brazilian canoe makers.
The ones made in Japan are usually laminated forge-welded blades, heavy and durable with a square socket for a curved or straight handle. If you are interested in following up on this here is a small collection of links: http://dougukan.jp/eng/dougu-e/e07chona.html
Takenaka Carpentry Tools Museum http://dougukan.jp/ http://www.hidatool.com/woodpage/axe,adze/adze.html
Traditional Crafts of Japan http://www.kougei.or.jp/english/metal.html http://www.japanesetools.com/tools/adzesandaxes/adzesandaxes.php http://www.fine-tools.com/G310632.htm
Tools of Canoe Carving http://www.uoregon.edu/~mspp/kapingamarangi/k10-too.htm
Echigo Yoita forged blades http://www.b-zenjapan.com/crafts/niigata_11.phtml
Lawrence
North Carolina, USA