The oar blade acts as unsteady hydrofoil in stroke phase. The authors¹⁾ carried out a tank test using a flat plate in the place of an oar blade in order to quantitively analyze the unsteady load acting on an oar brade. This time they carried out the same tank test but they used four kinds of real blade shape which have different aspect ratio or tip shape (Original- blade, High aspect ratio, Low aspect ratio, and Delta-blade). And they study the influence of aspect ratio and tip shape on the load acting on an oar blade.