"Ogive section" hydrofoil steering board.
I get many inquiries about my steering system.
I have highlighted in blue text my explanation of rudderless steering in a previous post;
"Takapu The Proa, a dissertation" under "Proa-dynamics, in the water"
The last paragraph in the chapter also highlighted in blue is headed "Dagger board steering"
Tim Anderson also explains Toroa's steering system very well in his "Home away from home page" site.
His explanation and photos can be found here:
http://web.media.mit.edu/%7Etim/pix/2004_nz/50_nz_4-15-04/_nz13.html
or alternatively click on the "Tim Anderson" link box at the top left of this page.
Best
Harmen